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<p><b>Directing attention. </b>The process of paying attention can be shown to act through selective recognition by nerve cells. Touch sensory receptors in the skin are known to fire impulses, when pressure is applied on the skin. Such messages are relayed to the cortex in several stages. Consider a relay neuron which transmits impulses from a touch sensory receptor on the shoulder to the cortex. Let us assume that, among its many inputs, this reporting neuron receives impulses from EAC through a single dendrite. The reporting neuron may normally be inhibited to prevent an overload of sensory data to the cortex. The signal from EAC may be recognised by the neuron as an instruction to re-transmit received messages. When it recognises the input from EAC, the reporting neuron may transmit received impulses from the receptor to the cortex. These impulses simultaneously further inhibit neighbouring sensory neurons, thus highlighting the message. By sending nerve impulses to the distinct neurons, EAC may create awareness of the pressure of cloth on the shoulder.
<p><b>Awareness and consciousness. </b>This reasoning points to increased awareness as a process, which causes inhibited sensory neurons to fire. Recognition of EAC impulses by reporting neurons may focus attention by creating localised awareness. Attention may become the process of increasing awareness in a local sensory region. Signals from EAC may act by causing inhibited sensory relays to fire. Such control fibres may be linked to the entire sensory system to enable EAC to focus the attention of the mind on any sensory input. A similar group of fibres may constitute a consciousness channel, which may aid the mind to be generally aware of sensory inputs. Impulses in this channel may instruct inhibited sensory neurons to begin reporting sensory events, to wake us into consciousness, with global awareness. When this channel is inhibited, there may be no sensory awareness. The channel may be inhibited when we sleep. A consciousness channel may wake us up, just as EAC focuses attention. Currently, awareness, attention, and consciousness remain mysterious processes, which stand in the way of an understanding of the mind. If we accept the possibility that individual nerve cells perform acts of recognition at the most rudimentary levels, we may explain many such intelligent activities of the mind.
<A NAME="5"><p align="center"><H1>Memory</H1>
<p><b>Current knowledge regarding memory is limited. </b>There is little current knowledge about how memory is stored in the brain. (12) Some researchers suggest that memory is stored in specific sites and others that memories involve network functions, with many regions working together. This essay suggests a method for the storage of human memory and a mechanism of its recall. This explanation forms an enabling requirement to support the insight that instant recognition is a key function of the mind. This follows the hypothesis that nerve cells act as primary recognition devices at the most fundamental level. Such a premise can explain how memory enables nerve cells to support intelligent networks, recognition of entities and habitual motor functions. This view of memory structure is vital for all the functions of the mind, as described in this essay. This section provides an overview of how a nerve cell may store a memory and how the nervous system may recall a memory.
<p><b>Recognition requires memory. </b>At the input and output levels, the firing by a nerve cell signifies a finite event. Receptor cells interpret these sensory inputs and send impulses. These impulses are relayed to the cortex in several stages. At an intermediate stage, a cell may receive messages from multiple locations representing multiple categories of such information. The modification of the sensation of pain, or the focusing of attention were suggested to act through the recognition of incoming messages by reporting cells. This essay suggests that a cell fires when it receives a distinct pattern which it recognises. To &quot;recognise&quot; is to establish an identity. The identity of any entity can be established only when it has a known relationship to certain characteristics. Knowledge requires consistency. If a cell knows a relationship, it must fire every time the relationship is recognised. So, the cell must store a memory of this relationship, if it is to recognise it. If a cell has the power of recognition it, must have a memory. It is suggested that such memory may be an ability to selectively recognise different combinations of incoming nerve impulses.
<p><b>The structure of memory.</b> A nerve cell, with say, 26 dendritic inputs coded from A to Z may have a memory for combinations of simultaneous inputs, such as CDE, DXZ, etc. The neuron can be said to store a memory for each combination, if it fires (or is inhibited) on receiving simultaneous impulses at C, D and E, or at D, X and Z. Each combination becomes a relationship which the cell remembers. Each cell has a functional specialisation. When it fires, it reports, or triggers a finite and unique event. The combination represents the relationship of this event to other events (CDE, or DXZ) it perceives. As suggested earlier, the pain reporting neuron fires for pain (P), sympathetic pain (SP) or pain and touch (P+T). It is inhibited by (SP+T). Each remembered combination becomes a unit of memory, which triggers a dependable response from the cell.
<p><b>A massive memory.</b> Perception of each unit of memory may cause the cell to fire, or to be inhibited. 26 characters can be arranged in millions of unique combinations. For a nerve cell with just 26 inputs, there can be millions of such units of memory. The cell may selectively respond to millions of combinations. Recognition on this basis may give massive selective intelligence to the nerve cell. Contemporary research has so far failed to locate a physical location for human memory. The possibility suggested here can point to incredible memory capabilities in individual nerve cells. If an individual cell can have such a large memory, imagine the total memory capacity of 100 billion cells! The concept may also highlight the problem of memory recall. There may be as many units of memory as the number of grains of sand on a beach. The task may truly be the equivalent of locating a needle on a beach.
<p><b>A memory at a synapse.</b> High frequency stimulation of of the dendrites of a neuron have been known to improve the sensitivity of the synaptic junctions. This phenomenon (13) is called long-term potentiation (LTP). Since such activity is seen to be &quot;remembered&quot; by the cell through greater sensitivity at specific inputs, LTP is considered to be a hopeful direction for research in locating human memory. This essay suggests that memory derives from a pattern recognition function. It may follow from the cyclic recognition of the unique features of the multitudes of dendritic inputs of a neuron. A neuron may become more sensitive to an individual input through LTP. Neurochemicals at the synaptic junctions have also been known to increase such sensitivity. But, memory may derive from the gobal pattern recognised by the nerve cell rather than from a greater sensitivity to a specific dendritic input.
<p><b>Cell memory feasible. </b>Each microscopic living cell contains the DNA molecule which carries within it the entire blueprint for a human being. Recognition codes in cells interact in the handling of the millions of chemical interactions in the body. The immune system is also known to use powerful code recognition systems. Under the circumstances, it is feasible that the protein neuroreceptors which mediate neuronal interactions (or the innumerable chemical synaptic intermediaries) contain sufficiently powerful memories and code recognition systems for the sustenance of a practically limitless memory in each nerve cell. If such a massive memory exists within each one of billions of nerve cells, there is the possibility of an astronomically large human memory - trillions of trillions of megabytes in computer terms. Acceptance of the presence of such an immense memory may take us a step further in understanding the awesome power of the mind. It may also create a massive barrier to AI in its efforts to imitate human intelligence.
<p><b>The memory of nerve cells may be for patterns. </b>Recognition requires a memory for the cell. Instead of just 26 inputs, many nerve cells have thousands, or even hundreds of thousands of incoming dendrites. 26 inputs can be represented as characters on a page and each unit of memory as a group of characters, such as ABC or CDE. But, with hundreds of thousands of inputs, the closer equivalent is a pattern of dots on a screen - a picture. With Boolean logic, the pattern would consist of dots, which are either on, or off, with a defined frequency. The memory of a nerve cell would be its ability to store in memory and so recognise multiple patterns of dots - the pattern of incoming dendritic impulses on a cyclic basis. This cyclic pattern of dots is the equivalent of a black and white picture. Recognition of a picture triggers an impulse from the cell, indicating that the current incoming information has relevance to this particular cell. Each nerve cell may have a memory for millions of such pictures, recognising individual pictures to respond with impulses, or with inhibition.
<p><b>Memory must be recalled in context. </b>Wherever memory may be stored, it concerns a whole lifetime of activity and is available for instant recall. A threatened animal carries a potent memory bank of past perilous experiences. It has memories of initial sensory indications of danger, of muscular responses for battle and of escape routes from the battle zone. With contextual memory recalled within fractions of a second, the whole power of experience is brought to focus on the ongoing task of survival. A contextual filing system for memories is a vital requirement of life. Contextual use of memory existed from the beginning of evolution. (14) In the early aeons, &quot;Nosebrains&quot; recalled memories for smells to decide if an object was edible and to be consumed, or inedible and to be avoided. Smells became the file pockets which triggered physical activity. Simple odour based filing systems in vertebrates evolved to more sophisticated feeling based systems in mammals. Feelings provided context for many subtle shades of activities, including leisure, play, upbringing of the young, and mild hostility, or deadly combat. This essay suggests that feelings may provide the key to the recall of memory.
<p><b>Feelings and emotions are real. </b>But, for centuries, feelings were discarded by scientists as not being part of the rational modern mind, a throwback from primitive times. It was Charles Darwin who first suggested that emotions have a real world existence, visibly expressed in the behaviour of humans and lower animals. The existence of an emotion could be derived from an angry face, or even a bad feeling in the stomach. Later theory suggested that each emotional experience is generated by a unique set of bodily and visceral responses. Visceral responses switch the nervous system between the sympathetic system which supports energetic activities and the parasympathetic system, which supports relaxation. (15) Subsequently, this view was disputed by W.B. Canon. He countered that emotions do not follow artificial stimulation of visceral responses. Emotional behaviour was still present when the viscera was surgically or accidentally isolated from the central nervous system.
<p><b>Nerve impulses can represent feelings.
</b>This view that emotions have an independent existence is supported by current research. Euphoric states of mind are created by drugs. (16) Electrical excitation of certain parts of the temporal lobe of the brain produces intense fear in patients. Excitation of other parts cause feelings of isolation, loneliness or sometimes of disgust. (17) The feeling of pleasure has been shown to be located in the septal areas of the brain for rats. The animals were observed when they were able to self stimulate themselves, by pressing a lever, through electrodes implanted in the septal area. They continued pressing the lever till they were exhausted, preferring the effect of stimulation to normally pleasurable activities such as consuming food. All experimental evidence over the years suggests that nerve impulses can trigger feelings. This fits in with the reasoning that nerve impulses represent finite events. In such a case, a group of fibres which carry feeling impulses can be viewed as a picture in a channel, representing the real time feelings in the system.
<p><b>The limbic system - a feeling centre. </b>(18) In 1937 Papez postulated that the functions of central emotion may be elaborated and emotional expression supported by a region of the brain called the limbic system. This system is a ring of interconnected neurons containing over a million fibres. These fibres also pass through the thalamus, the main nerve junction to the cortex mentioned earlier. The limbic system is a feedback ring with impulses travelling in both directions. (19) This essay suggests that the pattern of impulses in this million fibre channel of the nervous system may represents our global feelings - a feeling channel. For a system which is constantly interpreting nerve impulses, the cell of origin of the impulse indicates whether the impulse represents a point of light, a pitch of sound, an element of pain or a twinge of disgust. Feelings are triggered as nerve impulses which represent measurements of the parameters of the system. They are ever present. The pattern in this channel reflects the current feeling and may provide the context for the recall of memories by the mind. Feelings may be expressed as a picture with a million dots. This essay suggests that each subtle variation of the picture could recall a specific memory.
<p><b>A sensory map on the cortex. </b>It was reasoned that nerve cells store memories in the context of their relationships. Such data must be stored somewhere to be recalled. It is widely known that the brain physically isolates each pixel of sensory information. (20) When light enters the eye, it passes through the lens and focuses its image onto the retina. The light is received by special cells in the retina called rods and cones. Light-sensitive chemicals in the rods and cones react to specific wavelengths of light and trigger nerve impulses. About 125 million rods perceive only light and dark tones in an image. 6 million cones receive colour sensations. The light from a single rod is perceived as a microscopic spot of light when impulses reach the visual cortex. (21) Similarly, the tones heard by the ear reach a region of the cortex called Heschl gyrus. There is a spatial representation with respect to the pitch of sounds in this region. Like a piano keyboard, tones of different pitch or frequency produce signals at measurably different locations of the cortex. Each pixel of sensory information terminates in a specialised complex on the cortex. The entire sensory inputs to the mind impinges as a picture in a region of the cortex. Consider the possibility that the memory of each sensory image is stored exactly where it is received. There is experimental evidence of this possibility.
<p><b>A Barrel to store memory. </b>Each of the millions of sensory signals is finally known to reach a specialised barrel of cells in the cortex. (22) In 1959 Powel and Mountcastle identified this complex as the elementary functional unit in the cortex. Each unit is unique. It is a vertical column of thousands of nerve cells within a diameter of 200 to 500 microns, extending through all layers of the cortex. Let us call this unit a Barrel. Research has demonstrated the functional specialisation of each Barrel. Each Barrel represents a single pixel of sensory information. The neurons of one Barrel are related to the same receptor field and are activated by the same peripheral stimulus. All the cells of the Barrel discharge at more or less the same latency following a brief peripheral stimulus. The activation of one Barrel indicates the arrival of one finite element of information to the cortex. A single rod reports the incidence of light on a microscopic spot on the retina. The impulses from this cell are carried through the optic nerve to a single Barrel in the visual centre in the cortex. The firing of a Barrel in the primary visual cortex signifies the perception of a point source of light by the mind. This essay reasons that memories may be stored in the same Barrels.
<p><b>Barrel - logical location for memory. </b>The firing of one Barrel represents a single pixel of the global sensory information. The location of the Barrel defines it as a point of light, a pitch of sound or a pressure point on the skin. The firing of a pattern of Barrels is interpreted by the mind as a sensory image. The Barrels will fire when the image is received. If the same Barrels fire again, a memory of the same image will be recalled. It was reasoned that a memory may be recalled in its context. Feelings may provide that context. Feelings are the logical filing references for the recall of memory. Feelings form a picture in the feeling channel. It was reasoned that nerve cells store memories of relationships. These relationships were stored as pictures. It is now suggested that such a memory may be recorded into a Barrel. The current feeling may be recorded into the memory of all Barrels which receive the current sensory perception. Each Barrel recalls the relationship of this feeling and fires. When this feeling is recalled again, the same Barrels fire and the sensory memory is recalled. For this reasoning to be plausible, feelings must have access to each barrel.
<p><b>A &quot;non-specific&quot; access. </b>If feelings trigger the firing of Barrels and the resultant recall of memory, then the feeling channel must have access to each Barrel. Curre