KARL JASPERS FORUM

TA32 (Muller)

Response 6 (to C5 by Rifat)

BRAIN AND CEREBRUNCULUM
by Herbert FJ Müller
2 January 2001, posted 30 January 2001

Claude Rifat proposes a solution to the mind-brain relation with the help of an auxiliary concept which I discuss in the following. The paragraph numbers are those used in C5. My responses are in [brackets].

<1> " … examining the brain based only on exogenous methods cannot give a full understanding of how a brain works. As we inhabit a brain it is very useful to observe two different states of consciousness endogenously, namely the waking state of consciousness and the oneiric state of consciousness. "

[ "Inhabiting a brain" is a possible way of talking about the relationship between mind and brain. But it pre-supposes the brain as an ontological (ie, mind-independently structured and given as such) object, and this causes a problem, since "the brain" is on the contrary an entity which like all objects we build inside our experience. This MIR assumption leads to the insoluble question how to connect the immediately accessible experience (mind, consciousness) with a mind-independent (and thus mind-inaccessible) brain. The difference between waking and oneiric experience cannot help further with this. ]

" <2> … a crucially important structure in the CNS of which the purpose is to control information flow from Memory to consciousness … named the attenuator … and it was subsequently discovered that this attenuator was functional during the waking state but non-functional during the oneiric state. … "

[ The conceptual difficulty then leads CR to posit an auxiliary " … structure in the CNS of which the purpose is to control information flow from Memory to consciousness …". The proposed function of mediating between "exogenous" brain (CNS, and apparently here also memory) and "endogenous" experience (mind, consciousness) is that of a homunculus, a psychological construct which has now been abandoned. Its postulated role in psychological theory was analogous to that of the aether concept in 19^th century physics, which had also been invented to deal with a conceptual problem, but was later discarded because it was neither supported nor needed. ]

" The discovery of the attenuator had predictive scientific value as it implied that a major aspect of the serotoninergic system was to attenuate information transfer between Memory and consciousness. This was confirmed when it was observed that specific serotoninergic re-uptake inhibitors (SSRIs) had attenuating properties on recalls and that these attenuating properties led to a state of consciousness where the amount of thoughts per unit of time was drastically reduced, thus explaining the pseudo "anti-depressant" effects of SSRIs which are, in fact, conceptually, not "anti-depressant" effects but *thymoanaesthetic effects*. "

[ This, and the further remarks in CR's commentary, are an attempt to justify his auxiliary concept with the help of neuro-pharmacological mechanisms. Since CR talks about a CNS structure rather than a brain-inhabiting little observer, he might object that it is a cerebrunculum rather than a homunculus. But this does not change the conceptual aspect as described above. It is not possible to correct a conceptual error by experiment or other objective argumentation. In particular, the "transfer between memory and consciousness" is opaque, as mentioned. Actions of serotonin and of various pharmaca can help with the objective study of brain function including mental illness, but the conceptual relation of brain function to experience is a separate question. ]

[ " … for our objective knowledge of the world, including the brain and its functions, we are … dependent on our structures of thinking, and these can only arise within momentary overall (ie, self-and nature-)experience. … Concepts must in principle intend the whole of experience, both interior (self) and external (environment, world), though each of both to varying degree. Neither naïve or explicit ontological objectivity nor ontological solipsism are for this reason able to ask the proper question concerning the mind-brain relation. Both imply erroneously a primary subject-object split … " (from TA32[50-52]). Such a primary (ontological) s/o split assumption is the underlying problem in CR's proposal, it seems to me. ]

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Herbert FJ Muller