4. Notes on the relevance of neurophysiology to self-knowledge

In ‘Self-knowledge as an imperative with comments by David Parker’’ (on my website) I write: ‘When we become aware of the profound discrepancy between our physical brain and the world of our consciousness, we realize that there must be another entity, different from the brain, which transforms the data processed in the brain into the world of our consciousness … Since our brain with all its neurons is located in the skull, this entity must also be located in the skull, for only thus it can transform the data processed by the brain into the world of our consciousness. The nature of this entity, composed as it is of a subconscious and conscious part, must be fundamentally different from the nature of the brain, for the world we are conscious of is not interfered with by the physical processes in the brain, by the electrical currents and chemical transmitters generated by neurons.’

David replies: But how do we know that it isn’t? Again, an example. Running a marathon is not explained by the molecular events associated with the actin and myosin fibrils in a muscle, changes in calcium etc.. in a single or even 100 muscle fibres. But running a marathon is due to, amongst other things that drive you to run it, activity in large numbers of muscle cells, together with a skeleton, tendons, ligaments, joint forces that result from the musculo-skeletal system etc…

I wrongly expected that the word ‘interfere’ would prevent misunderstanding. So let me give examples of ‘interference’, which I have in mind, in contrast to ‘influence’ David speaks of. Chemical neurotransmitters, which are produced in the pre-synaptic cell, are stored in synaptic vesicle; these, are acted on by the action potentials; released into synaptic clefts, neurotransmitters act on the receptors in the post-synaptic neuron …

None of this enters my consciousness, although nothing of what I am conscious of, as I am typing these lines, takes place without all those activities that take place in my brain, and influence my consciousness through the intervention of my subconscious. Conversely, the keyboard on which my eyes are fixed as I am typing, the computer monitor on which I glance from time to time to check what I have written – none of it ‘interferes with’ the action potentials and neurotransmitters in the brain, for it has no place among those activities, although a great amount of neural activities in different nerve centres in my brain (in visual cortex, auditory cortex, somatosensory cortex, motor cortex) are influenced by my seeing the keys, their shapes and their black colour contrasted with the white colour and the shapes of the letters, by my seeing and moving my fingers, by my hearing the sound of the keys as I press them …

David continued: … Why shouldn’t there be consciousness from the integrated activity processed to a high level in the brain (and this does not need to be any specific site, it could be distributed).

I continued: ‘It follows as a matter of course that this entity cannot be interfered with, detected or manipulated by any physical instruments by means of which science detects physical phenomena in the brain.’

David remarked:  Again, why not. We cannot find the site of consciousness, despite various sites (cingulate gyrus, claustrum etc…) being given this role. This could be due to two reasons: there is no one site but it emerges from the activity of several sites; we simply lack the technology to detect it. It is not long ago that neuroscience did not know how neurons signalled within themselves (action potentials) or to other cells (synapses). These events occurred for millennia even though we have only detected them in the last 80 years or so.

Aristotle may help; he notes that topos (place/space) has three dimensions (diastêmata echei tria), length (mêkos), breadth (platos) and depth (bathos), by which all body is defined (hois horizetai sôma pan). This might suggest that topos is a body, and so he says: ‘But the place cannot be body (adunaton de sôma einai ton topon); for if it were, there would be two bodies in the same place (en t’autôi gar an eiê duo sômata)’ (Physics, 209a6-7, tr. Hardie and Gaye). ’Two bodies cannot be at one and the same place’ (duo sômata adunaton hama einai, 213b20)

Everything that neurophysiology has so far detected and can ever detect in the brain by the technology corresponds to Aristotle’s notion of body: where is neuron A, there cannot be neuron B, where is a vesicle A containing neurotransmitter ‘a’, there cannot be a vesicle B containing the same (or different) kind of neurotransmitter. Concerning action potentials, let me take recourse to Wikipedia: ‘The action potential generated at the axon hillock propagates as a wave along the axon … The currents flowing in due to an action potential spread out in both directions along the axon. However, only the unfired part of the axon can respond with an action potential; the part that has just fired is unresponsive until the action potential is safely out of range and cannot re-stimulate that part.’

I am going to type ‘I’. There must be at least one neuron that is activated by my seeing the letter ‘I’ on the keyboard, let it be neuron A. My finger presses the key ‘I’. There must be at least one neuron B in the motor section of the cortex, which is activated as I press the key. Let us presume that the axon of neuron A, outstretched to neuron B, activates neuron B. Neuron A and neuron B are located in the visual and motor cortex respectively; they interact via the axon of A without changing their places. But when I type letter ‘I’, my seeing the key and my pressing the key get united in the space of my mind, which can be viewed as the Kantian space (see ‘The Kantian subjectivity of space and time’, June 14 , and ‘Kant’s space contrasted with Aristotle’s space’, July 4). The Kantian space of mind is toto caelo different from the Aristotelian topos of the brain; only the latter can be accessed and studied by virtue of technology.