Walter J.Freeman How Brains Make Up Their Mind

Phoenix 1999     pg 27 Action If the brain does not merely react to received stimuli, how do actions originate in the brain?  If the external world is infinite in the sensory stimuli that it gives to the body, how does the brain select what is of immediate importance for it?  When awareness occurs, what is its biological nature, and what does it do?  Is awareness necessary for meaning, and if so, in what way?  Above all, how does the activity of neurons produce the unity, wholeness and intent that characterises intentional behaviour and meaning?   Neurons and Neuron Populations These difficult questions have biological answers, and I will begin by outlining my view of brain organisation.  There are two basic units:  the neuron and  the neuron population. The neuron is a specialised cell that acts upon another cell by transmitting an electrical impulse called an action potential, by which it releases a specialised chemical called a neurotransmitter.  For the past century, neurobiology has been based on the "neuron doctrine" and the study of neurons one at the time. However, just as important as neurons acting individually upon one another are masses of interacting neurons and neuron populations, which have specific properties of their own that cannot be reduced to the level of the single neuron.  The neuron populations have states and activity patterns just as neurons do, but they do different things.  We call this population activity macroscopic to distinguish it from the microscopic activity of individual neurons.   Action potential -  Activity pattern Microscopic - Macroscopic The world has effects on aggregates of microscopic neurons in sensory organs, which do not interact but individually send their action potentials into the brain.  The brain acts into the world by microscopic motor neurons that send their action potential to muscle cells. Between the non-interactive aggregates of sensory and motor neurons, it is the distinctive properties of neuron populations in our brains that enable us to deal with macroscopic things, like our bodies, the things we can build, the people we love, attack or run away from. Perception is organisation of sensations and the construction of meanings, and this is what neuron populations do.  When a microscopic receptor responds to a stimulus, such as an odorant, it transduces its input to an electrical current and into action potentials that it sends to the brain, where macroscopic neuron populations create an activity pattern.  This is, basically, the pattern of electrical brainwaves recorded by an electroencephalogram. These macroscopic patterns, whatever they are, are crucial to understanding brain functions. The microscopic view fails to account for my data in at least two respects: A sensation from an odorant does not create a pattern in the brain that is fixed and stored away in a memory bank.  Instead, I have observed that the brain’s activity patterns are constantly dissolving, reforming and changing, particularly in relation to one another.  When an animal learns to respond to a new odour, there is a shift in all other patterns, even if they are not directly involved with the learning. There are no fixed representations, as there are in computers, there is only meanings.  Second, a sensory stimulus from an object does indeed induce the formation of a pattern in the brain, but when it is given repeatedly it does not induce precisely the same pattern in the same brain, let alone in any other brain.  This is to be expected, because not only does the same object mean different things to different people, its meaning for the same person is continually shifting.  My conclusion is that meaning cannot be transferred directly into and between brains in the way that information and knowledge based in representations can be transferred into and between machines.  You can drill meaning into your children's brain about the piano keyboard and the multiplication table, but only if you induce them to practise, and then the forms are what the children make of them, not what you might want. You have to elicit meanings, and these are constructed and transmitted by the populations, not the individual neurons.   Materialist, cognitivist and pragmatist VIEWS To relate the properties and operations of neurons and populations to the mental experience of meaning, I will contrast three modes of interpreting the experimental data we have from the neural and cognitive sciences about the nature of the mind.  Within the general framework of the history of philosophy and psychology, there are three dominant views: materialist, cognitivist and pragmatist, of which my theory falls into the pragmatist category.  We will look at these theories in order to get some useful vocabulary to enter relate neuroscientists with philosophy and psychology. Materialist View: The materialists view mind as physical flows, whether of matter, energy or information, which have their sources in the world.  Minds are aspects of the flows happening in the brain that are causally linked, or even identical, to bodily processes.  The materialist position traces its provenance to the ancient Greeks.  Present-day materialists think of atoms and chemicals made of atoms, such as genes and enzymes, as the physical vehicles for the performance of brains and bodies not materially different from plants and solar systems except in the way that they are organised. This approach is given as comprehensive bodies of data on the structure chemistry and physiology of neurons and their development, and maps of their functional connections in sensory and motor systems.  Materialist have repeatedly had striking successes in the past two centuries, notably in the use of chemicals to treat and prevent diseases from infection, malnutrition and ageing, in the use of chemicals and surgical operations to modify and control behaviour, moods and emotional state, and in the proof that certain behavioural traits, such as mental deficiency or a tendency to depression, are under partial genetic control. Behaviourists  laid the basis for a materialist strain in holding that all our behaviour is described by hierarchies of reflexes.  Neurobiologists and physiological psychologists have changed the players in the materialist view to neural networks, computational assemblies, and hormonal pools of neurons, but they retain the stimulus-response determinism.  For them, what is crucial is the activity of neurons, which are driven by stimuli, and which give neural commands for actions. They are started by stimuli that carry information, and culminate in responses that convey transformed information.  Simply put, brains process information by manipulating matter and energy. The problem with this view is that it fails to account for the ways in which attentions selects stimuli before they appear, or for the flexible specification of figures embedded in infinitely complex backgrounds - the face that leaps out that you in a crowd - or for the dependence of perception on action, or for the impact of our emotions on our qualia.  Philosophers have played on these limitations by asking how the meaningless firing of neurons can give rise to meaningful experiences, such as paying, fear, rage and so forth, or even be identical with them.   Cognitivist View: The cognitivists argue that minds are made not of energy of matter, but of collections of representations that constitute symbols and images.  They are software running on "wetware".  Like materialism, this form of idealism also originated in ancient Greece.  Plato believed that a world of ideas existed apart from matter, which contained a fixed set of ideal patterns, a kind of super geometry that guided the physical falls of matter that were realised as imperfect copies. Cognitivists have also been enormously successful in developing machines for information processing, and their view is quite popular today in various fields.  Noam Chomsky's approach to linguistics is an excellent example. Chomsky believes that there are deep structures laid down in brains, which provide an innate logical structure to all languages and which are implemented in differing details in various societies and cultures.  Another example is artificial intelligence.  In the 1940s, neurobiologists and logicians reconceptualised the functions of neural activity.  They conceived of neurons as binary switches performing Boolean algebra and forms of Aristotle's logic.  Action potentials of neurons were no longer interpreted as electrical pulses, but as bits of information, binary digits that represented on or off, yes or no, one or zero.  This led rapidly to the development of programmable digital computers, all starting from a mistaken view of how neurons work. Information, according to the cognitivists, is carried by symbols that are manipulated according to prescribed rules.  When they apply this doctrine to brains, they deduce that information is given by stimuli from the environment. It is encoded in trains of action potentials as bits that represent qualities, aspects or features of the stimuli.  The features are transmitted by axons that serve as channels to the brain, where they undergo binding into representations of the stimuli by synaptic networks of neurons acting as summing junctions and logical gates.  The contents are stored in memory banks as representational fixed patterns.  They are recalled by being read out like the content addressable memories in computers, so they can be matched and correlated with representations of new inputs. The important consequence of this conception is that information replaces energy and matter is the carrier of the flow of ideas.  But information theorists have made it explicit that the information is divorced from meaning.  What is crucial is not the content of a telephone call, but this bandwidth and the number and timing of the bits required to transmit the message. Cognitivists following this approach to construct artificial intelligence face a difficult problem, because they do not know how to attach meanings to the symbolic representations in their machines.  The problem stems from the understanding of intentionality as "aboutness", the relation to the world of the symbols that represent thoughts and beliefs about the world.  Awareness is implicit in thinking and representing.  Some biological systems have consciousness but, as Franz Brentano pointed out, so far, inanimate machines do not, because they do not have intentions. But what is the nature of consciousness?  How is it made by brains?  How might it be made to operate in artificial intelligence brains to bring about changes in the machine parts and in the behaviour of the entire system?  There is a great deal of debate within the cognitive science community concerning precisely these issues.  Consciousness is a great mystery.  The problems are intractable because, in a field of cognitive science, meaning is defined by relation between symbols, as in syntactical definitions of words by other words and pictures in dictionaries.  But in reality, references to the world are not defined within a dictionary or a computer. Pragmatist View: The third view of mind is pragmatism.  Pragmatists think that minds are dynamic structures that result from actions into the world.  In 1272, Aquinas introduced Aristotle to Western Europeans (particularly in his Treatise on Man), and to Aristotle's doctrine of active perception, according to which the organism learns about the world and realises its potential by its action on the world.  He further proposed that each animal is a unified being enclosed within the boundary that distinguishes "self" from "other", and that the self uses the body to push its boundary outwards into the world.  Etymologically the word "intend" comes from the Latin word "intendere", which means not only to stretch forth, but equally importantly to change the self by experiencing action and learning from the consequences of acting. Actions of the body exit by the motor systems, changing the world and changing the relation of the self to the world.  The sensory consequences of the action then enable the body to change itself in accordance with the nature of the world.  However, the perception is only of the altered contours of the self as experienced inside.  No forms are pushed through or across the boundary.  The key word Aquinas used is "assimilation" (adeaquatio means towards, but not at, equality).  The body does not absorb stimuli, but changes its own form to become similar to aspects of stimuli that are relevant to the intent that emerged from within the brain.  Forms are created inside the self through achieving similitude.  The meanings of the objects then grow in accordance with what to have done to them and what you intend to do next, perhaps to taste, drink or offer a cup to someone else.  Other people can watch what you do and learning by imitation, so their meanings are similar to yours but are home-grown, not transplanted. Pragmatism has repeatedly failed to take centre stage in the neural and cognitive sciences because it poses a major problem.  If minds are actions into the world, how are these actions generated? According to both the materialist and cognitivist views, an action is ultimately determined by the form of a stimulus.  The laboratory rat can be trained to sit inertly until it is provoked.  A computer terminal waits for instructions from the user before it acts.  But wild animals and children don't wait. They are continually engaging the environment, seeking stimuli with their own expectations and designs. Where in brains do endogenous actions of search and observing come from?  How to brains generate them?  Materialists and idealists for centuries, even for millennia, have appealed to myths of external powers that drive us, such as the sun, moonbeams, the Big Bang, universal databanks, icons, totems, possessive demons, the world of energy that Chinese physicians call qi, and the connections to the spirit world by trees planted in sacred places, now transmogrified into nerve energy and the power of charismatic preachers.

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