Sunday, July 19, 2015

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

Dear David,

In my letter of July 11 I wrote to you that your entry on the website of the Department of Physiology, Development and Neuroscience at Cambridge University compelled me to interrupt my work on Aristotle and Kant and respond to your comments on my ‘Self-knowledge as an imperative’ (I was in the middle of writing a blog entry on ‘Aristotle’s concept of time’). And so I wrote the ‘Notes on the relevance of neurophysiology to self-knowledge’, in the last of which I contrast the Aristotelian topos of the brain with the Kantian space of the mind.

I now intend to resume my work on Aristotle and Kant, but before doing so I must give vent to nostalgia that possessed me as I was reading the entries on the website of your Department. Although I came to Oxford in 1980 at the invitation of the Master of Balliol, the first seven months of my stay at Oxford University was funded by King’s College Cambridge, and so I requested that I might spend the last of those seven months at King’s College; that month lies in my memory as an exquisite treasure.

As I was writing my ‘Notes’, I could not help thinking, how great it would be, if I could spend a month at Cambridge University as a visitor at your Department. What an investigative journey that would be for me!

But back to reality. Apart from your entry, let me refer to just one of the entries that I found highly interesting. Paloma T. Gonzales-Bellido’s laboratory tries to find out what is the optimal neural strategy and performance for a certain visual task. She is particularly interested in the visual performance of small predatory flies, investigating how killer flies keep track of their target during their short and fast predatory flights and how the visual information about small moving targets is coded and transferred from the photoreceptors to the motorneurons controlling flight. Furthermore, she studies how the behaviour is driven by the underlying physiology and morphology of the neural system, employing high speed videography (in the field and in the laboratory), electrophysiology (intracellular and extracellular) and microscopy (light and electron). Her work seems to me to be analogous to your work on the lamprey, by virtue of which you want to promote our understanding how neurons interact in the networks that process sensory inputs, perform cognitive functions, and program motor outputs.

I have been particularly impressed by your criticism of Grillner and Jessell’s ‘Locomotor network of the lamprey’. The authors present the network scheme as ‘characterized’, i. e. that behaviour of the lamprey can be explained in terms of interactions between identified nerve cells and their associate molecular, cellular, and synaptic properties. In your view ‘this network is at best hypothetical, and at worse knowingly wrong; neurons are included without their network relevance being established, others are removed for personal convenience, and approximately 50% of the synaptic connections, which are claimed in print to have been verified experimentally, lack any experimental evidence at all’.

In the light of your research, Carpenter and Reddi’s claim sounds hollow: “In a nutshell, ‘brain versus mind’ is no longer a matter for much argument … So far has brain encroached on mind that it is now simply superfluous to invoke anything other than neural circuits to explain every aspect of Man’s overt behaviour.” (Neurophysiology, 5th ed., Hodder Arnold 2012, p. 294)

1 comment:

  1. Dear Julius,
    The linkage of neuronal effects to behaviour in simpler systems like flies, snails, carbs, through fish, frogs etc.. has a long history. It really took off after the 2nd world war when people started to move away from a behaviourist perspective that ignored the nervous system and studied input-output (stimulus-response) functions. Up until this time most, not all, neurophysiology had been performed on mammals, but the complexity of these systems then, and still, makes direct links difficult, hence the drive to use simpler systems.
    In terms of the lamprey, Grillner, not Jessell, is responsible for the claims to understanding. I spent several years in his lab and started by working in the context of his framework of the understood neuronal network that generated swimming behaviour in the animal. I ran into problems on this after a couple of years, I couldn't find certain connections between neurons that were claimed as identified, and neurons didn't seem to be able to do the jobs assigned to them. None of this was open to discussion, things I couldn't find were "difficult to find", convoluted explanations were given to make things that didn't seem to work work. It was only on being given a review by a man called Rovainen who popularised the lamprey as a system from the mid-60's and who had found similar problems and suggested an organisation that went against Grillner's that things became clear.
    Carpenter and Reddi's claim is not necessarily wrong or hollow, it is simply that the causal links between neurons to behaviour, even in simple systems, are difficult to make. I would say that the mind is a reflection of brain/neuronal processes, but given that we are lost in trying to understand the interactions between a handful of neurons, when you take the billions of neurons we have understanding how mind arises from brain, and I realise that the debate goes on as to if it does, is never going to be an easy question.
    All the best

    (Not the whole letter, but the most relevant parts)