Brain, Reality, and Tao (道) (2020 Edition)

Purposes of Having Brain

There are two types of living organisms in this world. The autotrophs (self-nourishment) live on inorganic materials, while the heterotrophs (different-nourishment) must make use of resource that comes from other organisms in the form of fats, carbohydrates and proteins (Figure 01). Brains exist because the distribution of resources necessary for survival and the hazards that threaten life vary in space and time. There would be little need for a nervous system in an immobile organism or an organism that lived in regular and predictable environment. Brains are informed by the senses about the presence of resources and hazards; they evaluate and store this input and generate adaptive responses executed by some mechanisms.

Figure 01 Heterotrophs

Some of the most basic features of brains can be found in bacteria because even the simplest motile organisms must solve the problem of locating resources and avoiding toxins. They sense their environment through a large number of receptors, which are protein molecules embedded in the cell wall. Action is taken in response to the inputs such as the gradient of the chemicals (see Figure 02). Thus memory is required to compare the inputs from different locations. The strength of the signal is modulated by immediate past experience. This in turn regulates the strength of the response sent by chemical messengers to the flagellar motors. Thus even at the unicellular level, the bacteria have already possessed the ability to integrate numerous analog inputs and generate a binary (digital) output of stop or go.

Figure 02 E. coli's Response to Chemical Gradient [view large image]

Therefore even at such primitive level, the brain would modify the signals from the environment and generates a response, i.e., its survival does not directly depend on perceiving the real thing. It doesn't care about reality so cherished by philosophers.

Evolution of Brain

In multicellur organism, cells specialized for receptor function are located on the surface. Other cells specialized for the transmission and analysis of information are located in the protected interior and are linked to effector cells, usually muscles, which produce adaptive responses (Figure 03). As do unicellular organisms, neurons integrate the diverse array of incoming information from the receptors, the resultant my induce the firing of an action potential (when the summation is above a threshold level) to initiate a response. Once the threshold for generating an action potential is reached, the signal is always the same, both in amplitude and shape (a nerve consists of many neurons, it does not obey the all-or-none law, see "Neurons and Nerves").

Figure 03 Neurons and Nerve [view large image]

Phyla	Brain Structure
Sponges	None. But have nervous components such as synapses and neuro-transmitters. See "Origin of Nervous System".
Cnidarians	They have nervous network connecting outer and inner layers of cells; also possess light-sensitive cells.
Flatworms	There is a small brain and two lateral nerve cords joined by cross branches.
Roundworms	The brain is in the form of ganglia. There are nerve cords along the body connected by commissures.
Cephalopods	They have the most complex brains of any invertebrates, very good eyesight.
Annelids	There is a ventral nerve cord and lateral nerves. The brain is just a ganglion.
Arthropods	The nervous system includes a dorsal brain and nerve cords, ... - similar to the Annelids' but more advanced.

Table 01 Evolution of Brain (click small icon to view large image of the nervous system)

must invest a great deal of effort in raising their infants. Young reptiles function as miniature versions of adults, but baby mammals and birds are dependent because of their poor capacity to thermo-regulate, the consequence of their need to devote most their energy to growth. Most mammals solve the problem with maternal care (Figure 05), shelter, warmth, and milk. In most birds, both parents cooperate to provide food and shelter to their young. The expanded forebrain and parental care provide mechanisms for the extra-genetic transmission of information from one generation to the next. This transmission results from the close contact with parents during infancy, which provides the young with opportunity to observe and learn from their behavior; the expanded forebrain provides an enhanced capacity to store these memories. The expanded forebrain and the observation of parents are probably necessary for the establishment of

Figure 05 Maternal Care [view large image]

successful care giving behavior itself, as the young mature into adults that will in their turn have to serve dependent young. During the period of infant dependency, baby mammals and birds play, behavior that may be essential for the development of the forebrain. The baby's playful

Human Brain Structure

		The human brain can be divided into three parts: the hindbrain, which has been inherited from the reptiles; the limbic system, which was first emerged in mammals; and the forebrain, which has its full development in human. Different views of the human brain are shown in Figures 06, 07, and 08. Table 02 lists the functions of the different parts of the human brain. The brain is separated into two hemispheres. Apart from a single little organ -- the pineal gland in the centre base of the brain -- every brain module is duplicated in each hemisphere. The left brain is calculating, communicative and capable of conceiving and executing complicated plans -- the reductionistic brain; while the right one is considered as gentle, emotional and more at one with the natural world -- the holistic brain.
Figure 06 Human Brain 1	Figure 07 Human Brain 2 [view large image]

The cerebral cortex is covered in a thin skin of deeply wrinkled grey tissue called the grey matter (densely packed neurons for information processing). Each infold on the surface is known as a sulcus, and each bulge is know as a gyrus. While the white tissue inside are axons -- tentacles which reach out to other cells (to relay information). The cortex can be broken down into many functional regions, each containing thousands of cortical columns (oriented perpendicular to the cortical surface). Columns are typically about half a millimeter in diameter and contain about one hundred thousand neurons. They are the units of cognition (the mental process of acquiring knowledge by the use of reasoning, intuition or perception).

Figure 08 Human Brain 3 [view large image]

Table 02 below lists the location and functions of the major components in the human brain.

Table 02 Human Brain

The Malleable Brain

Table 03 The Five Stages of Human Brain

Figure 09 The Four Stages of Human Brain [view large image]

which the window of opportunity slams shut, and learning anything new in that realm becomes difficult, if not possible (Figure 10). For years, it is assumed that the brain's plasticity, or the ability to learn within the critical periods, was the work of excitatory neurons, which encourage neighboring neurons to fire. Recent study using inhibitory neurotransmitter (such as GABA) indicates that inhibition actually causes the onset of the critical period. It is found that termination of the mental process can be separated into two categories - structural and functional. The former involves physical structures such as neural network and is not easy to change; while the latter is just chemical compounds not difficult to administer. It may be very useful to reopen the critical period later in life. However, no one should

Figure 10 Learning Curves [view large image]

tamper the brain's critical periods casually. There is always the possibility of an adverse response, as we break the rule of nature.

Senses

Sight, Hearing, Smell, Taste, Sensations, Balance

		as listed Table 04, while Figure 10a shows many types of receptors. When a receptor is stimulated, it generated nerve impulses that are transmitted to the spinal cord and/or the brain, but we are conscious of a sensation only if the impulses reach the cerebrum. It is immediately clear that reality of the external world is transformed to nervous impulses via various kinds of receptors. The brain then interprets the inputs as colors, sound, pain, ... These kinds of sensations
Figure 10a Senses [view large image]	Figure 10b Cerebrum [view large image]	are one level away from the real things such as electromagnetic waves, sound waves, molecules in various states of motion, ... In other words, the brain just offers a very subjective experience.

Table 04 Receptors

Sight (see location of the various components in Figure 10a)


Figure 11a shows the evolution of optical perception from Jelly fish to cephalopods :


• Box Jellyfish have eye pits and rhopalia all over the body. It is found that at least one species of jellyfish uses these eyes to navigate and to avoid bumping into obstacles (see "Through Unique Eyes").

		Development of photo receptor and nerve fibers started from hydras. The perception is a hazy spot similar to the audio perception in modern human. It just provides an indication on the level of intensity from the source. Eventually, higher animals acquire lens for adjusting the brightness, retina for sorting out different wavelengths, and a brain to compile a vivid picture as shown below.
Figure 11a Evolution of Eyes	Figure 11b Human Eye [view large image]

The eye depends on many components as shown below to see such wonderful world :


• Sclera - This is the white of the eye. It is a tough whitish sheath covering most of the eye (see Figure 11b). The inter-cellular space contains a kind of loose proteins composed of collagen and elastic fibers, which make the wall of the eyeball more pliant.
• Cornea - It is almost perfectly transparent at the front of the sclera for the protection of the eye. Light rays is refracted through this dome-shaped structure.
• Choroid - The soft layer inside the sclera. It has many blood vessels that nourish the eye. It also absorbs stray light.
• Ciliary body - The choroid becomes suspensory ligaments near the opening. It holds the lens in place, and controls the shape of the lens for near and far vision.
• Iris - Further toward the opening, the choroid becomes a thin, circular, muscular diaphragm known as the iris, which regulates the size of a center hole (the pupil) and thus controls the amount of light entering into the eye. The pupil gets larger in dim light and smaller in bright light.
• Aqueous humor - This is the anterior cavity between the cornea and the lens. It is filled with an alkaline, watery solution secreted by the ciliary body. Normally, the solution leaves the anterior cavity by way of tiny ducts that are located where the iris meets the cornea. When a person has glaucoma, these drainage ducts are blocked, and aqueous humor builds up. The resulting pressure compresses arteries that serve the nerve fibers of the retina. The nerve fibers begin to die due to lack of nutrients, and the person becomes partially blind.
• Lens - It is a fat disk that completes the focusing of light rays into a clear, sharp image on the retina. Actually, the cornea provides about 80% of the focusing power. The lens is stretched by the ciliary muscles to fine-tune the focus by changing the shape, so it becomes fat for near objects, thin for far ones.
• Vitreous humor - The posterior cavity behind the lens contains a viscous, gelatinous material. It forms the bulk inside the eyeball and, with the outer sclera, gives it firmness. It also helps to refract light rays toward the retina.

		Retina - Inside each light-sensitive cell (rod or cone) in the retina are up to 100 million molecules of photopigment, each of which contains a smaller molecule known as retinal (Figure 12a). When retinal receives light energy, it changes shape by twisting around its backbone. The altered retinal sets off a chain of chemical reactions inside the cell, which triggers an electro-chemical change in the cell membrane creating a nerve impulse. The retinal returns to its original configuration when the signal jumps across a synapse to a bipolar cell. Curiously, in order to reach the photoreceptors, incoming light must first pass through all the other layers of cells in the retina.
Figure 12a Retinal [view large image]	Figure 12b Retina [view large image]	There are five layers altogether (see Figure 12b). Starting from the outermost layer:

1. Pigment epithelium - Epithelial cells are the guards and protectors of the organ. They cover the surface and determine which substances are allowed to enter.
2. Rods and cones - These are the photoreceptors. The rods are responsible for night vision, and the cones for color vision. The retina has as many as 150 million rods but only 1 million ganglionic cells and optic nerve fibers. This means that there is considerable mixing of messages and a certain amount of integration before nerve impulses are sent to its final destination. The photoreceptors achieve the remarkable sensitivity (of a millionfold difference in luminance) with adjustment relative to the average background. But if the overall background level of illumination were to change drastically, as it does when we enter a dark room, we are effectively blind for a few minutes until the rod photoreceptors have adapted to this level of reduced intensity. Vision is most acute in the fovea centralis (see Figure 10a), where there are only cone cells. Clear vision is possible only when the fovea inspects a scene. This provides a very restricted window of clarity. Thus in order to obtain a clear picture, the eyes have to dart about frenetically and automatically under the direction of the brain.
3. Bipolar cells - Nerve signals from the rods and cones pass inward to this layer. The bipolar cells together with the horizontal and amacrine cells form the network of pre-processing nerve cells. The network helps to simplify, and code information before it reaches the optic nerve.
4. Ganglionic cell layer - It receives input from the pre-processing network, and send output to the brain via the axons of the ganglion cells.
5. Optic nerve - It is made up of nerve fibers, which come from across the whole retina. They pass in front of the retina, forming the optic nerve, which turns to pierce the layers of the eye. The signals eventually end up in the occipital lobe to form an image.

Optic Pathway - As shown in Figure 13, information about the left visual world is transmitted to the right side of the brain and vice versa. As the visual fields of the eyes overlap in the front, this division is achieved by sorting retinal ganglion cell axons according to whether they look at the left (dotted line) or the right (solid line) visual field. So some axons from the right eye go to the right side of the brain and others to the left. The sorting occurs in the optic chiasm. The retinal axons proceed to the lateral geniculate nuclei where the first synapses are fromed with the visual neurons in the brains.

Figure 13 Optic Pathway [view large image]

Hearing (see location of the various components in Figure 10a)

Table 05 below compares the various features of light and sound :



	Light	Sound
Velocity	c = 3x1010 cm/sec = = constant, it propagates in transparent medium as well as in vacuum	v = (Ks/)1/2 ~ 3.5x104 cm/sec (in air), where Ks is the bulk modulus, the density of the medium
Frequency	Visible Range : (8 - 4)x1014 Hz, depends on E = h	Audible Range : (20-20k) Hz, same as the vibrating source
Intensity	I = L/(4R2), where R is the distance to the source, L the luminosity (intrinsic brightness = power)	Measured in dB = log10(I/I0), where I0 = 10-12 w/m2 is the hearing threshold for human
Type	Transverse, polarizable	Longitudinal
Presence	Every where in day time, ubiquitous. Localized at night	Depend on space/time of the vibrating source, localized
Imaging	Form vivid 3-D image instantly	Construct virtual image by sound pattern or language
Vitalness	Most life form depends on light	Not essential for most life form

Table 05 Comparison of Light and Sound

	Figure 14a shows the range of loudness level for human. It appears that most of the sources are localized and monotonic. It requires the addition of patterns like singing or talking to convey more information. The measuring unit is in dB, dB = 0 means absolute silence for human ears. Figure 14b displays the audible spectrum for different species. The ranges for some natural
Figure 14 Hearing Level and Range [view large image]	phenomena represent the varying frequency as the wave propagates through medium of varying density (see "Properties of seismic waves").

The ear depends on many components as shown below to hear the vibration from a source :


• Outer Ear -
  • Pinna - This is the external flap for collecting sound wave.
  • Auditory canal - The opening of the auditory canal is lined with fine hairs and sweat glands. The modified sweat glands secrete earwax to guard the ear against the entrance of foreign materials, such as air pollutants.
• Middle Ear -
  • Tympanic membrane (ear drum) - It pushes a set of three small bone (the ossicles) against an inner membrane.
  • Ossicles - The three parts in this structure are: hammer, anvil, and stirrup. These components multiply the sight vibration of the sound by about 20 times. When the stirrup strikes the oval window, the pressure is passed to the fluid within the inner ear.
  • Eustachian tube - It extends from each middle ear to the nasopharynx and permit equalization of air pressure. Chewing gum, yawning, and swallowing in elevators and airplanes help to move air through the eustachian tubes upon ascent and descent.
• Inner Ear - Whereas the outer ear and the middle contain air, the inner ear is filled with fluid. Anatomically speaking, it has three areas: the first two, the semicircular canals and a vestibule, are concerned with balance; only the third, the cochlea, is concerned with hearing. It is a very delicate and sophisticated organ about 1 cm³ in size.
  • Scala vestibuli - The incoming vibration (red arrows in Figure 15a) spirals along this structure toward the apex of the cochlea. At the apex, a small gap allows the wave to pass into the scala tympani.
  • Scala tympani - The wave travel down (blue arrows) in this spiraling tube toward the round window.
  • Round window - It acts as a pressure relief membrane dissipating the vibrational energy.
  • Organ of Corti - This structure is set onto the basilar membrane which forms one of the arms of the Y inside the cochlea (see Figure 15a). Pressure changes in the fluid outside the scala media create vibrations in the basilar membrane and in the Reissner's membrane, which forms the other arm of the Y. The vibrations in the scala media and the tectorial membrane shake the hair cells, which convert the vibrational energy into electrical nerve impulses. The signals are channeled by nerve

    		fibers along the organ of Corti to the main cochlear nerve, and then to the temporal lob of the brain for processing into the sounds that we perceive. According to the frequency of the sound wave, different parts of the basilar membrane along the organ of Corti are set into motion. In general, low-pitch sounds make the apex of the cochlea vibrate while high-pitched ones cause most vibrations near the base of the cochlea. Figure 15b shows such frequency distribution along the length of the cochlea for both the incoming and outgoing waves. The strength of nerve signals also depends on the volume of the sound. This is interpreted by the brain as loudness. It is believed that tone is an interpretation of the brain based on the distribution of hair cells stimulated.
    Figure 15a Cochlea [view large image]	Figure 15b Sound Wave [view large image]

  Smell (see location of the various components in Figure 10a)
  
  Communication via chemical message (smell) can be traced back to bacteria, which use the signals to coordinate their behavior

  		within a group (see "Prokaryotes"). Higher animals subsequently develop more elaborate mechanism to perform various functions (Figure 16a). Depending on its usefulness in a particular environment, different kinds of animals possess different number of receptors (Figure 16b). Some chemical message can elicit a specific reaction such as sexual arousal, it is called "pheromone".
  Figure 16a Smell Detection and Functions [view large image]	Figure 16b Receptor #, Animals'

  The sense of smell depends on many components as shown below to sample the scent from the nose to the brain :
  
  

  Nasal cavity - This a large air space above and behind the nostril. Three shelf-like ridges of bone (nasal conchae) are there to deflect air. In normal breathing, air flows through the lower part of the cavity, past the rear of the soft palate and into the throat (Figure 16c). A good sniff sends the odor eddying up into the roof of the nasal cavity, where it comes into contact with the olfactory apparatus. Mucus layer - Only those odor molecules that can be dissolved in the mucus, become the stimulants to the receptor sites on the cilia.

  Figure 16c Sense of Smell [view large image]

  Cilia - These are the hairlike projections from the olfactory sensory cells, and trigger the sensory cells to generate nerve signals if the receptors recognize the shape of the odor molecules. It is estimated that the human nose contains about 1000 different types of olfactory neurons, each type able to detect a particular set of chemicals.

  Bowman's gland - This gland makes the mucus. Olfactory sensory cell - It is embedded in the olfactory epithelium. Nerve signals pass upward along the cell body, which narrows into a wire-shaped nerve fiber, or axon. The axons from thousands of sensory cells group into bundles and convey their nerve signals to the olfactory bulb. Olfactory bulb - In this structure, the axons form complicated ball-shaped sets of connections with the mitral cells. These connection area are olfactory glomeruli, and there are hundreds in each olfactory bulb (see Figure 17). Each glomerulus receives signals from more than 25000 sensory cells and has tens of thousands of connections from the mitral cells in the bulb itself. Much sorting and processing of the signals takes place in the glomeruli. The resulting nerve messages are sent along the olfactory tract to the olfactory area in the brain.

  Figure 17 Olfactory Bulb [view large image]

  Olfactory area - Nerve signals representing smells are routed to two regions of the brain: the medial (inner) olfactory area and the lateral (side) olfactory area in the amygdala. Figure 18 shows the pathway of the odorants in the air, which initiates impulses moving along the nerve pathway to the brain. Since the nerve pathway is in part of the brain's limbic system, which also deals with memories and emotions, smell can evoke strong emotion from past experience about a certain odor. Smell is the sense in which habituation occurs most quickly. Habituation is the process in which a sense becomes accustomed to what it detects so that it is no longer perceived. Most odors can hardly be perceived just 30 seconds after they are first detected. The sense of taste and the sense of smell supplement each other, creating a

  Figure 18 Pathways [view large image]

  combined effect when interpreted by the cerebral cortex. For example, some of the molecules may move from the nose down into the mouth region and stimulate the taste buds there. Therefore, part of what we refer to as smell actually may be taste.

  
  
  Taste (see location of the various components in Figure 10a)
  
  Table 06 below compares the various features of smell and taste :
  
  

  	Smell	Taste
  Messengers	Gaseous molecules in surrounding	Usually organic molecules in food
  Input	From nose	From mouth (the 2 senses mix at the back of the mouth to create flavor)
  Range	Some distance away from the source, short range	In mouth, very close contact
  Processing	Dissolved in mucus, to receptor, to neuron, to brain	Same, but in different region of the brain (see )
  Purpose	To access favorable and avoid harmful substance (evaluation, before reaching for it)	To consume yummy and reject poisonous food (already in mouth)
  Threshold	200 - 0.0005 ppm (decline with age, see List)	0.01 - 10-6 M (Molar = mol/L, decline with age, see List)
  Absence	The molecule does not induce the sense of smell (caused by no receptor, long exposure, illness, ...)	The food is tasteless (caused by long exposure to the same food, illness, also see "Loss of Taste")

  Table 06 Comparison of Smell and Taste

  Here's the components for tasting foods :
  
  
• Tongue - Embedded within the surface of the tongue are four types of taste receptors localized in specific regions on the

		tongue (see Figure 19, also a 2010 version). Each detects a different class of chemical: sweet (sugars), sour (acids), bitter (complex organics), and salty (salts). The "hot" sensation of foods such as chili peppers is detected by pain receptors, not chemical receptors. But a report in 2006 reveals that contrary to popular belief, there is no tongue map. Responsiveness to the five basic modalities - bitter, sour, sweet salty and umami (a Japanese word meaning the savory or meaty taste of amino acids) is present in all areas of the tongue.
Figure 19 Tongue [view large image]	Figure 20 Papillae [view large image]

Taste buds - The tasting, or gustatory, cells in the buds have hairy tips which detect chemicals in solution (secreted by the gland at the bottom of papilla). When stimulated by flavor molecules, these cells generate nerve signals, which they send to the taste center on the brain's cortex, and also to the hypothalamus, which is concerned with appetite and the salivating reflex. Taste nerve pathway - The nerve signals are carried by three nerves in each side of the tongue (cranial nerves) to a small part of the medulla (brain stem). The signals then travel to parts of the brain, such as the hypothalamus, the thalamus, and the gustatory part of the sensory cortex - the "taste center", where the signals are interpreted (Figure 21). The thalamus acts like a relay station, shunting the data onto appropriate cortical areas for processing. The sense of taste tells us what is good to eat. It evolved to pick out sweet, ripe fruits and energy-packed sugars and starches. Likewise, taste is is extremely sensitive to bitter flavors, because many poisonous berries, fruits and fungi are bitter-tasting.

Figure 21 Sense of Taste [view large image]

Sensations (see location of the various components in Figure 10a)


• Skin - Skin has a thin epidermis, which is mainly for protection, and a thicker dermis below. In addition to small blood vessels and sweat glands, it has tiny nerve endings in the various type of touch receptors (see Figure 10a).
• Receptors -
  • Bulb of Krause - These are multi-layered capsules with many branched nerve endings. They are quick-change mechanoreceptors, triggered by rapid alterations in shap caused by pressure or vibrations, and may also help us to feel extreme cold.
  • Free nerve endings - They have a treelike branching system of naked nerve fibers. They are the most common sensory endings in the skin and detect just about anything - light touch, heavy pressure, heat, cold, and importantly, pain. Slight stimulation of these nerve endings may elicit the sensation that is known as itching.
  • Meissner's endings - They are found in the uppermost part of the dermis, especially on the hands, feet, lips, and inner surfaces of the eyelids. They are shaped like eggs and are both quick- and slow-change mechanoreceptors, detecting light touch and vibrations.
  • Merkel's endings - They are like tiny disks stuck in the underside of the epidermis, where they feel slight changes in its shape, thereby detecting light touch. They are both quick- and slow-change mechanoreceptors.
  • Pacinian endings - They have layers like an onion and are sited deep in the dermis. They pick up heavy pressure and also fast vibrations, such as those from a tuning fork.
  • Ruffini endings - They respond to sustained stress or gradually altering shape. This means that they are slow-change mechanoreceptors. They are found mainly in hairy skin and are sausage- or spindle-shaped. It is thought that they may also detect extreme heat.
• Proprioceptors - The sense of position and movement of limbs is dependent upon receptors termed proprioceptors (Figure 22a). They are located in the joints and associated ligaments and tendons that respond to stretching, pressure, and pain. Nerve endings from these receptors are integrated with those received from other types of receptors so that we know the position of body parts.
• Sensory nerves - Nerve impulses may reach the somatosensory cortex for analysis before a response is decided. These result in voluntary actions - a deliberate response. Sometimes the stimulus require immediate action (such as from the burning sensation), a reflex action is taken without the conscious control of the brain. These are the involuntary actions directed by the spinal cord. We

		only become aware of them when other impulses are sent to the brain to "inform" what has happened. The path which impulses travel along during a reflex action is called a reflex arc. Not all the body parts receive the same attention of the brain. The relative importance is often represented by mapping over the length of the sensory or motor cortex. These cortical maps (Figure 22b) are not drawn to scale; instead they are variously distorted to reflect the amount the neural processing power devoted to different regions. This accounts for the grotesque appearance of the human body in the homun-culus, which is a translation of the body's sensory map into the human form.
Figure 22a Propriocep-tors [view large image]	Figure 22b Homunculus [view large image]

Balance is an ongoing process that keeps our two-legged posture stable. Four main sets of sensory input are involved:


1. Information from the skin is important, especially from the touch and pressure sensors on different parts of the feet, which tell the brain if you are leaning. This sense is not available in a free falling environment such as in a spacecraft.
2. Eyesight is used to judge verticals and horizontals to which your body should be parallel and at right angle respectively.
3. The body's proprioceptive sense of stretch in muscles, tendons, and joints tell the brain about the positions and angles of the arms, legs, torso, and neck.
4. The sensory parts dedicated to balance is located deep inside each inner ear, next to the cochlea (see Figure 10a). These parts are known collectively as the vestibular apparatus and are part of the same network of fluid-filled chambers as the cochlea. They consist of the utricle, the saccule, and the semicircular canals (Figure 23a). In certain parts of their linings are tinny hairs, whose roots are embedded in lumpy crystals or gels. The crystals or gels are attracted downward by gravity, and they are also pushed to and fro by the fluid in the chambers, which swirls as the head changes its position.

The functions of the these organs are shown in Figure 23a: (a) The ampullae of the semicircular canals contain hair cells with cilia embedded in a gelationous material. (b) When the head rotates, the material is displaced and the bending of the cilia initiates nerve impulses in sensory nerve fibers for maintaining dynamic equilibrium. (c) The utricle and saccule are sacs that contain hair cell with cilia embedded in the gelationous material. (d) When the head bends, otoliths are displaced, causing the gelationous material to sag and the cilia to bend. This initiates nerve impulses in sensory nerve fibers for maintaining static equilibrium.

Figure 23a Balance [view large image]

The vestibular nerve feeds its information chiefly to the cerebellum and to four structures in the medulla known as vestibular bodies. Using these data, as well as input from the other three sensory sources, the brain works out what to do, usually subconsciously.

It turns out that such structure of hair within gel to detect disturbance has been around hundred of million years in the shark and fish (Figure 23b). This is the neuromasts embedded in the skin of fish. They give the fish information about the flow of water. Amphibians and reptiles have a simple uncoiled inner ear. Jawless fish has only one semicircular canal instead of three in mammals (for detecting three dimensional movement). Ultimately, it is the Pax 2 gene that give rise to these structures. It is also known that the Pax 6 gene is responsible for the development of eye. The connection to ancient creatures goes even deeper when it is found that the box jellyfish carries a gene which is the combination of Pax 2 and Pax 6.

Figure 23b Neuromast [view large image]

The box jellyfish is an amazing animal with more than 20 eye pits and many eyes very similar to ours. They seem to double for ears as well.

Now we known that it is the senses and the brain to keep us informed about the external environment through many special setups. In addition, the process consumes a lot of energy and requires intricate wiring (of neurons), it has to impose limits beyond which survival is not at stake (Figure 23c). For examples : the sight is limited to the visible range of the electromagnetic spectrum, the senses ignore those frequent inputs bearing no threat to life, and it processes inputs in discrete intervals (there are blanks in between that we are not aware of, see "Saccades"). Therefore, the brain not only distorts

Figure 23c Threshold of the Senses

the reality to suit the requirement of survival, it also neglects lot of details in order to expedite the task. It is definitely that we are not perceiving the reality, which is always modified by the brain.

Memory

As shown in Figure 02, the ability to modify our behaviour in response to life's experiences is shared by all animals including the bacteria E. coli. Such feat requires the brain's willingness to learn. Learning results in the formation of memories and in humans this process reaches its most sophisticated form, allowing us creatively to associate different reflections on the past, to generate new ideas, and most importantly to acquire language as a medium of expression and communication. Memory requires the brain to be physically altered by experience and it is this remarkable property that makes thought, consciousness, and language possible. The basic mechanism of memory formation is highly conservative over billion years of biological evolution. The difference in humans is that we have a lot more of the stuffs. There are about 100 trillion synaptic connections in our brain.

Figure 24a Memory Classification [view large image]

There are many ways to classify the memory. The concept of explicit and implicit memory refers to whether or not the recollection is produced consciously and intentionally. While the scheme of declarative and nondeclarative memory depend on the retrieval that can be declared verbally or not. Associative memory is triggered by clues; nonassociative memory can be habitual or sensitive. There are also short term and long term memory. One of the classification schemes is shown in Figure 24a. Table 07 is an attempt to put them all together. In the table, the declarative, and the procedural memory are explicit with the rest of nondeclarative memories being implicit. Only the working memory belongs to the category of short term memory fading away in hours, while the others are long term, and available for retrieval in years. Figure 24b shows the components, locations, and pathways for many types of memory.

Figure 24b Types of Memory [view large image]

Table 07 Types of Memory

• Working Memory -Most of our memories are fleeting because few of the many experiences we have in the course of an average day are remembered for very long, nor do they need to be. Transient memories are absolutely essential to the process of understanding the meaning of events as they occur in the present. This type of very short-term memory for things being experienced now is known as working memory; it allows you to comprehend what you are reading or to figure out the meaning of what has just been said to your in a conversation. Working memory can be thought of as a low capacity information reservoir that is always full, sensations flowing into it continuously at about the same rate that they are forgotten. Some of the information

held in short-term storage may be important enough to be remembered for a long time and must therefore be transferred to a more stable form of storage, which is represented by far more robust alterations in the brain's chemical and physical make-up in the form of synaptic connections. It is not necessarily for an important experience to trigger the formation of long-term memories, other factors such emotion, practice, and rehearsal also facilitate the transformation. Experiments show that in all cases the most important underlying distinction between the short- and long-term memory formation is that the latter requires a dialogue between synapses and genes and the former does not.

Figure 25 Working Memory [view large image]

The working memory itself is located in the prefrontal cortex. As experimental techniques became refined, it has become clear that there is no rigid dividing line between a memory and a thought. It has been described as the brain's scratch pad : the place where information is held and manipulated. It is used whenever effort is made to understand the incoming information. A model of working memory has been developed to combine perceptions, memories and concepts together, and consists of three parts:


• Phonological loop - Memory in this area (see Figure 25) enables us to remember sequences of approximately seven digits, letter, or words. The language areas of the brain are mainly in the left hemisphere, around and above the ear. The language loop start with hearing words in the auditory cortex and/or reading words in the visual cortex. Perception of language results from the convergence of auditory and visual information in Wernicke's area. Expression of language is controlled by Broca's area; while the angular gyrus is concerned with meaning.
• Visual-spatial scratch pad - It is like a sort of inner eye, which receives and codes data into visual or spatial images. For example, it comes into play when we need to remember where we were on a page when we start reading a book again. Functional imaging suggests that this complex structure represents the "what" and "where" in short-term memory (see Figure 25).
• Central executive - This most important yet least well understood component of the working memory model, is postulated to be responsible for the selection, initiation, and termination of processing routines (e.g., encoding, storing, retrieving). It is believed that this component coordinates information from a number of sources, directs the ability to focus and switch attention, organizes incoming material and the retrieval of old memories and combines information arriving via the other two temporary storage systems. It performs various tasks such as reasoning or doing mental arithmetic - rather like the RAM (Radom Access Memory) of a computer.




Nondeclarative memory - Nondeclarative memory includes skill learning, implicit learning, priming, simple classical conditioning, and habituation. These forms of learning are similar in that it is experience which changes the neural makeup, and the conscious access to past episodes is not essential for the formation of these memories. Implicit memory is not flexible and does not allow for the recombination of learned information. Nondeclarative memory does not require the hippocampus or related structures. Instead, the implicit learning of skills and habits depends on the neostriatum (basal ganglia and its connections to the frontal lobes). The conditioning simple skeletal muscle reactions depends on the cerebellum. The amygdala is essential for emotional conditioning.

Figure 26 Nondeclarative Memory [view large image]

Nondeclarative memory can be classified to five main groups :



• Procedural memory - It is the repository of such skills as handwriting or driving. These skills are essential part of our memory store, but it is difficult to describe the "know-how" in words. In this sense the memory is said to be implicit or non-declarative (Figure 26); you just cannot explain how to ride a bicycle. The skills may be difficult to acquire, but once learnt they are never forgotten, even without occasional practice. Thus it seems that the know-ledge or information required for the execution of very complex motor routines or procedures is somehow laid down in a robust permanent memory store. The parts of the brain involved in the acquisition of complex motor skills are the cerebellum and putamen (see Figure 24b). Deeply ingrained habits are stored in the caudate nucleus.
• Classical conditioning - Along with motor skills, conditioning is part of non-declarative memory. The desire for food at a particular time of day - regardless of whether hungry or not - is one example of such conditioning. A classical example is to associate the ring of a bell to food when feeding a dog. After repeating the training many times, the dog shows salivation at the ring of the bell even without food (see Figure 26).
• Fear memory - Recent study in delivering shocks to mice suggests that fear memory does not occur immediately after a painful event; rather, it takes time for the memory to become part of our consciousness. The initial event activates NMDA receptors - molecules on cells that receive messages and then produce specific physiological effect in the cell - which are normally quiet but triggered when the brain receives a shock. Over time, the receptors leave their imprint on brain cells. A phobia is an excessive or unreasonable fear of an object, place or situation. Examples include fears of specific things such as insect, snake, mouse, and flying. It seems that people can learn to suppress a fright reaction by repeatedly confronting, in a safe manner, the fear-triggering memory or stimulus. It is found that for specific phobias, up to 90% of people can be cured through such exposure therapy.
• Nonassociative memory - Nonassociative memory includes two forms of learning called habituation and sensitization. Habituation is defined as a decreased in response to a repeated stimulus such as a certain odor. On the other hand, sensitization is an increased responsiveness such as more sensitive in touching a cut in the skin. Nonassociative learning involves reflex pathways in the spinal cord and elsewhere.
• Remote memory - The memory of events that occurred in the distant past is referred to as remote memory. The underlying anatomy of remote memory is poorly understood, in part because testing this type of memory must be personalized to a patient's autobiographical past. What is known is that, like semantic memory, remote memory eventually becomes independent of the hippocampus. One memory model shows a linear representation of how experience is processed as memory: Stimulus Sensory Registration Attention Short Term Memory Consolidation - Retrieval Long Term Memory Remote Memory. At the stage of sensory registration, there is a matching/assigning of the pattern to a meaning. Attention focuses the brain to a task by filtering out the noises. Short-term memory is temporary and is limited in space. If short-term memory is not repeated, the information is lost fairly quickly. Long term memory is consolidated and stored throughout the nervous system. Remote memories represent the foundation memories upon which more recent memories are built. Since early acquired information is the foundation for new memories and may be linked to many more new memories, such memory is less subject to change and/or loss. Similar to the short-term memory, the remote memories are not usually affected by aging.



Declarative memory - Declarative memory covers the memory of facts such as events and names, which do not need to be repeated for them to sink in. Those experiences destined to be laid down as long-term memories are shunted down to the hippocampus where they are held in storage for 2 - 3 years. During this time the hippocampus replays the experiences back up to the cortex, and each rehearsal etches it deeper into the cortex. Eventually the memories are so firmly established in the cortex that the hippocampus is no longer needed for their retrieval. Much of the hippocampal replay is thought to happen during sleep. Dreams consist partly of a rerun of things that have happened during the day, fired up to the cortex by the hippocampus. The visual areas generate rerun of daily sightings (Figure27).

Figure 27 Long-term Memory [view large image]

Semantic, and episodic memory are the subclasses of declarative memory:

Episodic memory - It is about an event in one's life and everything about it, including emotional reactions. Remembering an episode, e.g., the attack on Pearl Harbour (Figure 28a), is to create a memory for a unique event that only happened once and there is no opportunity for learning the event by rehearsal. Episodic memories are not very reliable, they are highly personal, selective, idiosyncratic and varying over time, but they may also be richly complex and movie-like in character. They constitute the stories we tell ourselves about our past, they are the things we would write about in our autobiography. Episodic memories can be recalled deliberately or are triggered by evocative sensory stimuli - particularly by the sense of smell. Episodic memory involves the use of the hippocampus for forming memories and the cortex for storage (diagram D, Figure 24b).

Figure 28a Declarative Memory [view large image]



• Semantic memory - Semantic memory is the knowledge of facts - numbers, addresses, language and concepts - which the brain files in categories and seems to involve the left temporal lobe. Retrieval is then carried out by the frontal lobes (see diagram E, Figure 24b). We assume all of the facts that constitute our knowledge of things must be stored in an organized fashion to be useful. Though this has not been demonstrated, it seems likely that the brain stores our semantic memories as modules that have some logical links to one another; they are grouped by category for instance. On retrieval, the brain knows where to find the memory according to the address of that particular category. Semantic memory is essential to the understanding of how things work and thus to an understanding of the world we live in. It is a body of knowledge that helps us to regulate our behavior according to and dependent on reliable factual memories. Navigational skills, for example, depend on our ability to deploy a complex store of semantic memory, including detailed spatial memories and representations of the world. Logical and rational thought rely on knowledge in the semantic memory to overcome the belief and emotion evoked from the right brain. Usually the right hemisphere wins as logical thinking has to be acquired through training.


Memory is created by association between a group of neurons such that when one fires, they all fire, producing a specific pattern (see "Cell Assembly"). Thought, sensory perceptions, ideas, and hallucinations - any brain function is made up of this same thing. For example, a group of neighbouring neurons firing together in the auditory cortex would bring about the experience of a certain note of music. A memory is a pattern like these. The only difference is that it remains encoded in the brain even after the stimulation has passed. Memories form when a pattern is repeated frequently, or in circumstances that encourage it to be encoded. This is because each time a group of neurons fires together the tendency to do so again is increased. Once the neighbour has been triggered to fire, a chemical change takes place on its surface which leaves it more sensitive to stimulation from that same neighbour. This process is called long-term potentiation (LTP). If the neighbour cell is not stimulated again it will stay in this state of readiness for hours, maybe days. If the first cell fires again during this period, the neighbor will respond. The second firing makes it even more receptive and so on. Eventually, repeated synchronous firing binds neurons together so that the slightest activity in one will trigger all those that have become associated with it to fire, too. It is in such process, that a memory is made.

Observations from surgical removal (by mistake), brain scanning, and experiencing with rats have established that the hippocampus is the site for keeping long term memory by augmenting the number of neuro-transmitters and receptors (Figure 28b).

A memory is a collection of huge number of inter-connecting neurons called "Cell Assembly". It is estimated that there are about 1 billion cells in a human hippocampus storing at least 10000 different concepts; therefore each one of them would involve 100000 hippocampi neurons. While the hippocampus plays an important role, memory in the cortex is an integrated part for handling action, thought, sensory perceptions, ....

Figure 28b Memory Making [view large image]


The giant sea slug called Aplysia californica^¶ is often chosen for the studying of memory. Its brain has about 20000 neurons, some of which are large enough to be visible to the naked eye. Aplysia can learn and most importantly it is found that the mechanisms

and principles involved in its formation of short- and long-term memories are conserved throughout the animal kingdom, including in humans. Aplysia exhibits a behaviour of protective reflex in which the sea slug withdraws its gill into the safety of the mantel cavity in response to a mild touch stimulus to another part of the body called the siphon (Figure 29a). If the stimulus is repeated a number of times, the gill withdrawal reflex becomes weaker until finally the animal ignores the touch stimulus. The waning of sensitivity to repeated stimulation is known as habituation and is a very simple form of learning found in all animals, including humans. Another type of learning is sensitization, when we are exposed to an unexpected or strongly unpleasant stimulus. Generally the sensitizing effect of a single alarming stimulus is short-lived, lasting perhaps for just a few

Figure 29a Memory in Aplysia [view large image]

minutes. But if the alarming stimulus is repeated a number of times our senses may be heightened for days and now such sensitization becomes a form of long-term memory.

It turns out that short term changes involves only modification of pre existing proteins and alterations of pre existing connections. The short term process does not involve ongoing macromolecule synthesis. The effect wears off with time or repeated applications with no untoward happening. On the other hand, long term process involves a structural change which is not seen in the short term. In long term processes, there is a growth in new synaptic connections by sensory neurons onto follower cells. The growth of new synaptic connections is activated by the gene expression resulting in new protein synthesis.

At the macromolecule level, it is known that the neurotransmitter involved in the processes is the serotonin. A puff of serotonin alone can substitute for the siphon shock. It is shown further that the serotonin triggers the release of the second chemical messenger called cyclic-AMP. It activates an important type of enzyme called a kinase, which modifies the properties of particular target proteins by adding a phosphate molecule to them; the term for this is protein phosphorylation. The target for this modification in the sensory neuron is a potassium channel protein. It is mentioned earlier that a potassium channel is important in the downward phase of the action potential. The net result of phosphorylation is a prolongation of the action potential in the sensory neuron and so more neurotransmitter is released by the sensory neuron. Thus the sensory neuron's synapse with the gill motor neuron is strengthened. In short-term memory, special enzymes quickly remove phosphates from the proteins and return them to their original state, restoring the synaptic strength to its lower pre-sensitized level. However, following repeated serotonin delivery, the level of cAMP-activated kinase is much higher and this allows the crucial step in the formation of long-term memory to occur. This crucial step is the transport from the synapse to the cell body of kinase molecules that have been activated by c-AMP. Once in the cell body the activated kinases enter the nucleus and start to regulate the expression of particular genes. In Aplysia, proteins that result from this process of gene activation are transported back to the synapse where they are used to maintain the strength of synapses already affected by local effects of c-AMP and to grow new synaptic connections. So in Aplysia (as in other animals) the conversion of a short-term into a long-term memory involves the reinforcement of the short-term changes in synaptic strength and the growth of new synapses, both of which require the synthesis of new proteins.



As mentioned earlier, repeated activation yields a lasting increase in the efficiency of synaptic transmission -- a process called long-term potentiation (LTP) -- which is thought to underlie memory formation. LTP depends both on enhanced insertion of receptors for the neurotransmitter glutamate at spines (the sites of synapses) and on spine growth. Figure 29b shows the molecular basis of LTP as described in a 2008 neuroscience article. Essentially, it reports that the process is driven by the myosin V proteins, which shuttling receptors and membranes to make synaptic junctions better detectors of incoming signals.

Figure 29b LTP, Molecular Basis of [view large image]

A brief description for each step of the process is outlined in the following (also see Figure 29b):

1. Neurons receive synaptic transmission from other neurons (not shown) at dendritic spines.
2. Influx of Ca²⁺ through NMDA receptors activates the folded (inactive) form of the myosin V motor protein.
3. The active myosin V protein (in extended form) then moves to the dendrite shaft and binds to Rab11/Rab11-FIP2 on recycling endosome (reused membraneous sac) containing AMAP receptors.
4. Finally, it transports the cargo into and along spines via actin filaments (microtubules) to mediate insertion of AMPA receptors at the cell surface, as well as spine growth through membrane insertion.

		It is reported in 2007 that the seat of memory has been pinpointed in mouse. By monitoring 260 neurons in the hippocampus (Figure 29c), researchers have discovered that different experience is recorded in different area called "clique", which can be categorized from very general to very specific. Furthermore, such brain activities can be translated into binary codes (Figure 29d). Supposedly, we can read the mind from such codes and tell what it is thinking by the process of backward translation.
Figure 29c Seat of Memory [view large image]	Figure 29d Memory Code [view large image]	The followings are steps to uncover the memory code:

1. Recorded Experiences - The mice are exposed to three startling experiences - a puff of air on the back (to mimic an owl attack from the sky), a fall in a container (the "elevator" drop), and shaking in a cage (the "earthquake") - while a recorded plotted firing from a large set of CA1 neurons. Each row in the plot captures firing of a single cell over time.
2. Patterns of Mental Activities - The points in the 520 dimensional phase space (corresponding to the activities of 260 neurons before and after an event) are projected into a 3 dimensional phase space. Different mental activity falls into different area in such plot starting from "rest". Temporal analysis revealed that the activity patterns associated with those startling experiences recurred spontaneously at intervals ranging from seconds to minutes after the actual event, but with smaller amplitudes than the original response. Such patterns provide evidence that the information traveling through the hippocampal system was inscribed into the brain's memory circuits. The replay corresponds to a recollection of the experience after the fact.
3. Coding Cliques - It is discovered that neuron ensembles active during an event contain subsets -termed neural cliques. The cells in a clique all show very similar firing patterns and are not part of the other cliques.
4. Organization of Memories - Further analyses showed that each clique encodes a different aspect of an experience, ranging from the general to the specific. It can be visualized as a hierarchical organization with the most general clique at bottom, and the very specific on top. Any given pyramid can be a component of a more general polyhedron representing all events of a given category, such as "all startling events".
5. Translated into Binary Code - The clique activity is represented as a string of binary code with 1 as being active and 0 signifies inactivity. Thus the earthquake binary code is 11001 corresponding to: "starting event", "disturbing motion", "air puff", "drop", and "shake". While the elevator drop binary code is 11010 for the same sequence.

Unlike the brain itself and the senses, memory is further away from reality. It is used to compare current input with past experience and to take proper action as what the bacteria do since some hundred million years ago (see E.coli). A modern twist in human is to force the brain to fabricate a fiction which is an altered version of an event as perceived by everyone else (see "Why Memory isn't Reality").

^¶The challenge of finding an ideal model animal in which a physical basis of memory formation might be revealed was taken up in the 1960s by E. R. Kandel, who eventually received the Nobel Prize in Physiology or Medicine in 2000 for his efforts on investigating the nervous system with Aplysia. The Aplysia did not share the prize, but his daughter Minouche at the age of seven has written a poem to enshrine the animal:



	An aplisa is like a squishy snail. In rain, in snow, in sleet, in hail. When it is angry, it shoots out ink. The ink is purple, it's not pink. An aplisa cannot live on land. It doesn't have feet so it can't stand. It has a very funny mouth. And in winter it goes to the south.

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Reality and Tao (道)

In an article commemorates the 50th anniversary of the "New Scientist" magazine, Roger Penrose suggests that there are three kinds of reality: the physical, the mental and the mathematical, with something (as yet unknown) profoundly mysterious in the relations between them. According to this view, the various "Quantum Interpretations" are attempts to link the mathematical reality to the physical or mental reality. Figure 30 shows the mathematical reality as the patterns of interference computed from a mathematical formula, while the physical reality is in the form of photographic plate with the darker strip corresponding to the higher value of the curve. The mental reality is the image of dark and white strips formed in the retina and perceived by our consciousness (the brain).

Figure 30 Reality

He expounds the same view 14 years earlier in the same magazine in 2020. Insisting that there is a profound mathematical truth hidden from us. He has not yet come to terms with different levels of reality. Anyway, the ultimate real thing could be forever beyond our comprehension - something called TAO (道) as explained in the following.


Another scheme is to consider the physical reality as primary, while the mental and mathematical realities as secondary. In this view, some processing steps are required to arrive at the secondary reality such as neuro-activity and computation. But the secondary reality does not always produce a corresponding primary reality. For examples, dreams and other altered mental states are not real; and mathematical formulas can generate result, which has no match in reality (unless the concept of multiverse is invoked).

As the late Stephen Hawking (1942 - 2018) points out in an article from "Extreme Physics" (published by Scientific American, 2013) each theory may have its own version of reality and none of them can be said to be more real than any other. It is similar to the concept of "Effective Theory", which employs different method to describe different system.

And then according to Richard Feynman (1918 -1988), the quest to understand reality is a bit like watching a game of chess without knowing the rules. By observing the game, we slowly identify the pieces and how they are allowed to move and interact.


By observing the various pieces and processes as described in the previous sections, yet another scheme on understanding reality can be devised as shown below :


1. Subjective Reality - This is the perception received by the senses, then edited by the brain to produce a visual image, sometimes with sound, smell, and taste all for the purpose of survival originally. This is usually referred to as consciousness. Such reality is common to humans, although the perception is private (for example, you never know the quality of color perceived by other people - the "hard problem"). This reality is acquired through hundreds million years of evolution. Hence, animals would also have consciousness although it would be very different from the human's (see "Francis Crick Memorial Conference 2012"). In the beginning, bacteria had only simple reaction of just "go or no-go" to environmental stimulation. Plants can response "slowly" to levels of light, temperature, water. The wiring in human brain becomes so complicated now that we additionally can be nurtured to have feeling, emotion, various political, religious beliefs, and planning for the future, ... However, it's capacity is still limited by all kinds of restrictions as explained previously in this webpage (see full text). Here's a summary to recap :

   The original purpose of having a brain is for survival of the mobile organisms. The simple binary response of "go" or "no-go" has evolved to the very sophisticated human brain. Each step along the way would have different perception of the environment. Human brain is expensive consuming ~ 20 watts, i.e., ~ 20% of the body's energy use. The brain is malleable by nurture which instills different religious believe, political ideology, various personal preferences, ... Thus, subjective reality is different for different individual. The 5 senses receive inputs from the environment. The range of inputs is selected from those having impact to survival. It vanishes with the death of the organism. Memory is for comparison of past experience to the present predicament. For human beings, it is now recalled to generate feeling, emotion, ...

   Figure 31 Super-Reality

   Figure 31 is a painting of Lincoln by Salvador Dali, who tried to "resolve the contradictory conditions of dream and reality into an absolute reality, a super-reality, or surreality". He had success in crossing the boundary of the rather boring reality via his paintings at least.

   By corollary, "critter" in another world would have entirely different shape and organs according to Darwin's "Natural Selection".
   
   
2. Mathematical (Scientific) Reality -
   
   
   • Mathematical theory has to be verified by experimental and/or observational data. It is part of the science paradigm.
   • Observations with microscopes, telescopes and other modern instruments are the extension of the five senses.
   • The books, publications and other information storage systems are the extension of the memory in the brain to preserve the findings of the mathematical reality.
   • It requires learning to comprehend. It involves mathematics and diagrams.
   • It provides a middle ground between the subjective and objective realities.
   • The mathematical formula doesn't always makes sense. For example, various attempts try to explain the quantum theory to lay-person without much success (see quantum interpretations and a futile attempt to make it real in "Reclaiming Reality from Quantum Theory"). It is because animals and human never have such requirement to check out this microscopic world of very small scale (until this modern age for some scientists).
   • Simplified version is available to layperson (see Why the words we use in physics obscure the true nature of reality, and Figure 32 for a pictorial summary).
   • The brain is not intended to do science and math. That's why these subjects are so difficult to understand and learn.
   • Not all mathematical objects have a correspondence in the real world; black hole is mostly likely to occur at the core of most spiral galaxies; no white hole has been detected so far.

   Some people would reject such reality (at least part of it) based on past indoctrination (stored in memory), e.g., certain religious believes. It presents a consistent picture of the world (large and small) with only some problems (such as dark matter, dark energy). But that's OK as science may not provide an ultimate explanation for everything, it only offers a rational view according to the available knowledge. It is open ended in the sense that the knowledge and theory can always be updated or corrected.

   Figure 32 Mathematical Reality [view large image]

   Animals do not know mathematics, while the living world is too complicated for mathematical modeling, it is investigated by experiments. Origin of Life is still an ongoing quest.

   • Over the eon, humans have only a vague notion of time. Its precise definition was introduced by mathematicians and physicists to keep track of changes, i.e., it is defined as the "Rate of Change" (of something, see for example, the "Beginning of Time" in mathematical formulation). We perceive time at a single instance called "NOW". Humans (and other animals) need to be aware of what happens in the surroundings for the sake of survival at the exact moment which is NOW. The past is in the memory, while the future is unknown.
   • The mathematical reality is also incomplete as it can reveal only a simplified aspect of the real thing (mostly only for a single particle or statistically). It uses parameters to gloss over our ignorance from one reductionist's level to another. Not all mathematical formulas or equations have a corresponding physical counterpart. Those claim to be accurate to ten significant figures of the experimental data are formulated under very stringent condition or modeling.


3. Objective Reality - Although this level of reality is unfathomable, here's some comments nevertheless :
   
   
   • Deprived of senses and brain, the universe is completely dark, soundless, and no taste. It is similar to the predicament of deaf-blind children (see "Overview on Deaf-Blindness"); or just close your eyes for a moment to appreciate.
   • Humans on Earth depend on the brain and 5 senses to perceive a small part of this objective reality. Animals and extra-terrestrials have totally different subjective reality by sampling different aspects of the objective reality.

   	Everything described by the mathematical reality is approximately valid with all the basic components of particles and fields/waves intact. Macroscopic objects are still around. There would be objects and processes that mathematics or science fails to discover. In short, the difference at the objective level of reality from the subjective and mathematical levels is :
   Figure 33 Reality, 3 Levels	Its existence does not depend on the brain or any interaction to conjure up some sort of sensation; while the mathematical formulation offers only an approximate version. We may never know the exact nature of this objective reality (see illustration in Figure 33).


About 2500 years ago, the Chinese sage Lao Tsi (老子) dictated the "Tao Te Ching" (the Book of Tao, 道德經); the very first sentence stated : "The Tao that can be told, is not the eternal Tao" (道可道, 非常道). Since then the "Tao" has been interpreted as moral standard, extra-sensual experience, a theory, ...; while eternity often adopts the meaning of timelessness or immortality.

	Now according to the above context of different reality levels, the "Tao" (道) can be identified to the knowledge about the cosmos. Both the subjective and mathematical levels do not offer a complete explanation (but can be told). The real explanation is in the level of objective reality, but cannot be fully expressed in words or mathematics --- this is the "Eternal Tao" as envisioned by 老子.


The latest (2020) ideas about reality :
NewScientist has sponsored an one day event about "The Nature of Reality" on 28 March 2020.
The proceedings is published under the title of "The Nature of Reality" available from 1 April 2020, @ £9.99 (see free Round-up).
Also from the same magazine "What is Reality? Why We Still Don't Understand the World's True Nature".

Here's the 2024 Conversation with ChatGPT (in italic) about the "REAL" reality:

What is reality?

ChatGPT said:
"Reality" refers to the state of things as they actually exist, independent of perception, belief, or interpretation. It encompasses everything that is real and has actual being, including the physical universe, natural laws, and objective facts. Philosophers, scientists, and thinkers have explored the nature of reality for centuries, leading to various perspectives:
1. Philosophical Realism: This view asserts that reality exists independently of our thoughts, perceptions, or beliefs. In this framework, objects, events, and truths exist whether or not anyone perceives them.
2. Subjective Reality: In contrast, some argue that reality is shaped or even created by our perceptions and consciousness. This is often explored in theories of relativism and idealism, where the nature of reality depends on individual or collective experiences.
3. Scientific Reality: In science, reality is defined through observable phenomena, experiments, and empirical data. The scientific method seeks to uncover objective truths about the world by removing biases or subjective interpretations.
4. Virtual or Simulated Reality: With advances in technology, there's growing discussion about simulated realities, where what we perceive may be constructed or altered by artificial means, leading to questions about the nature of our existence.
5. Quantum Reality: On a subatomic level, quantum mechanics introduces the idea that particles can exist in multiple states simultaneously until observed, leading to questions about the fluidity or indeterminacy of reality at the smallest scales.

Each approach offers a different lens to explore reality, whether it's viewed as something absolute and unchanging, or as something shaped by perception and interaction.

So, reality depends on the beholder's perception - it is a belief (see ChatGPT's definition). I think the "REAL" reality is something we don't know and will never know as our knowledge is limited (despite modern scientific advances). Any comment?

ChatGPT said:
You've touched on a profound and often debated idea:
that the "REAL" reality might be something beyond our grasp, limited by human perception, cognition, and knowledge. This aligns with several philosophical traditions, especially those that question the ability of human beings to fully comprehend the ultimate nature of reality.

Here are a few reflections based on your point:
1. Kant's View (Noumenon vs. Phenomenon): Immanuel Kant argued that humans can only perceive the world as it appears to us (phenomena) through our senses and cognitive structures. The true essence of things-the "noumenon" or "thing-in-itself"-is beyond our direct understanding. In this view, we only experience a filtered version of reality shaped by our limited faculties, and the deeper, objective reality may be forever inaccessible.
2. Human Cognitive Limits: Even with modern science, our capacity to fully understand reality might be constrained. For instance, we are bound by our senses, biological makeup, and even the structure of our brains, which may limit how we perceive and process the universe. Theories like Godel's incompleteness theorems suggest that in certain systems, not all truths can be known from within that system, reflecting potential limits in understanding reality comprehensively.
3. The Observer Effect: Modern physics, especially quantum mechanics, suggests that the act of observation can influence the outcome of physical systems (e.g., the collapse of the wave function in the famous double-slit experiment). This brings up questions about how much of reality is "out there" independent of us, versus how much it is shaped by our interaction with it. It implies that perception may play an integral role in shaping what we experience as reality.
4. Mystical and Transcendental Approaches: Many spiritual or mystical traditions echo your thought, positing that there is a deeper reality or truth that is beyond the grasp of human logic or scientific inquiry. These views often claim that reality, in its most profound sense, transcends the material and empirical world, and can only be approached through non-rational means like meditation, intuition, or revelation (not necessarily, meditation may improve your health but will not provide insight into deeper reality as I have done the practise all the time).
5. Scientific Uncertainty: Even though science continues to make strides in understanding the universe, it's always in flux, evolving, and often confronting new uncertainties. For example, dark matter and dark energy account for most of the universe's mass-energy content, yet we know almost nothing about their nature. In this sense, scientific advances illuminate parts of reality, but also reveal how much remains unknown.

Your view suggests a healthy skepticism of the limits of human knowledge, despite our advances. It's possible that the "REAL" reality is something we can never fully know, given the constraints of perception and the evolving nature of our understanding. It's both a humbling and thought-provoking position to hold, acknowledging the mystery that still surrounds existence.

ChatGPT's definition of BELIEF :

Belief is the mental acceptance or conviction that something is true, real, or exists, often without the need for empirical evidence. It can be shaped by personal experiences, culture, education, or religious/spiritual influences. Beliefs can pertain to a wide range of things, such as ideas about the world, moral values, or metaphysical entities, and they are fundamental to how people understand and interpret reality.

Beliefs can also vary in strength and be based on different types of reasoning or authority, from scientific facts to deeply held personal convictions or traditions. For example:

" Empirical Belief: Based on observation or evidence, such as believing the earth is round.
" Religious/Spiritual Belief: Based on faith or spiritual teachings, such as believing in a deity or an afterlife.
" Cultural/Social Belief: Shaped by social norms, values, and traditions, like beliefs about gender roles or etiquette.

Beliefs guide decision-making, behavior, and how individuals relate to others and their environment. They can also be subject to change when new evidence or experiences challenge existing perspectives.

Go back to 道.