Memories and the brain
(An improved and updated version of this essay has appeared in my book Brief Peeks Beyond. The version below is kept for legacy purposes.)
|Olin Levi Warner's Memory (1896). Source: Wikipedia.|
For over a hundred years science has been looking for physical traces of memory in the brain and has, so far, largely failed in such endeavor. Indeed, this video illustrates one of the fundamental difficulties of the postulate that experiences are somehow materially encoded in the brain. Since memories are themselves conscious experiences, many take the inability of science to locate them in the brain as evidence that consciousness is immaterial, as opposed to being merely a result of brain activity. However, recent scientific papers – of which this one is just the most recent example as of the time of writing – have been putting forward new evidence for material memory correlates. We've debated this briefly in this thread of the message board. Nonetheless, in this article, I want to explore in a bit more depth whether this new evidence contradicts, in any way, the hypothesis that consciousness is not a result of brain processes.
There are three hypotheses for the immaterial nature of consciousness, and its relation to the brain, which I find particularly interesting:
- The so-called 'transmission' hypothesis, which postulates that consciousness exists in an immaterial realm, protruding into space-time through the brain. The latter is then seen as a kind of transceiver of consciousness, 'SCUBA gear' for consciousness to have a material experience;
- The so-called 'filter' hypothesis, which postulates that consciousness is fundamentally non-local and unbound, the brain working as a 'filter' that limits and localizes consciousness to a particular point of space-time. This hypothesis was popularized by Aldous Huxley in the 1950s;
- The 'brain as a knot of consciousness' hypothesis that I put forward myself.
The non-materialist hypotheses are consistent with the empirical observation that, ordinarily, subjective states of consciousness correlate fairly well with objective, measurable brain activity. That is why, for instance, your mental state changes when the brain is intoxicated with alcohol; why you get knocked out from physical trauma to the brain; or why you go to sleep under anaesthesia. Indeed, the 'transmission' and 'filter' hypotheses postulate that conscious experience is modulated by physical brain states in much the same way that planetary explorers' perceptions and actions in Mars are modulated by the robotic rovers' sensors and actuators. A similar rationale applies for the 'brain as a knot of consciousness' hypothesis.
Now here is the crucial point I want to make: According to the non-materialist hypotheses, certain brain activity patterns are, in a way, analogous to 'keys' that 'unlock' (not necessarily in a causal, but perhaps a synchronistic manner) the awareness of certain phenomena; phenomena that would otherwise be either unavailable to consciousness ('transmission' hypothesis) or kept out of it ('filter' and 'knot of consciousness' hypotheses). So why should it be different in the case of memories? Why shouldn't access to memories be correlated to 'keying' brain activity (which Rupert Sheldrake would call 'resonant' activity)? If the non-materialist hypotheses are to be internally consistent, that should in fact be the case. If physical events are found in the brain that correlate with memory access, that in itself would not contradict any of the non-materialist hypotheses, but in fact reinforce their internal consistency. Proponents of the non-materialist hypotheses should look forward to the discovery of clear physical correlates of memory access.
But one thing must be made clear: The non-materialist hypotheses entail that certain activity in the brain should correlate with memory access; but not necessarily that these physical correlates carry the entire information entailed by the corresponding memory. As Sheldrake explained through a clever metaphor, the 'transmission' hypothesis, for instance, looks upon the brain as a kind of TV tuner. Think of an old analog TV set: The electrical activity in the tuner circuitry causes it to resonate with a broadcast electromagnetic field in the air. It is the latter that carries the information of the TV show one watches, not the tuner. Nonetheless, activity in the tuner correlates well with the programming and, in fact, 'keys' into it. Naturally, trying to crack the TV tuner open to find the information corresponding to last night's show is futile, despite the correlation observed when the show was being watched through the 'keying' action of the tuner.
So when I say that the non-materialist hypotheses should entail physical correlates of memory access in the brain, that does not necessarily mean that the entire information associated with the memories is always in the brain (a TV show is not in the TV set). Therefore, a potential test of the non-materialist hypotheses, insofar as memory is concerned, is to estimate the amount of subjective information contained in a memory and compare that with the amount of information in the activated brain structures that supposedly store the memory. If the latter is lower than the former, the non-materialist hypotheses would be reinforced.
All this said, as a proponent of the 'knot of consciousness' hypothesis, I feel personally encouraged by the recent progress in finding physical correlates of memory access, since my hypothesis somewhat requires them to exist. Indeed, in my book Rationalist Spirituality I talked openly about there being 'symbols' (that is, correlates) of memory circulating in the brain. But I am very cautious about celebrating the progress just yet. If one looks at the different theories being put forward, one notices fairly quickly that they contradict one another; they cannot all be correct, so at least several of the claims recently made are baseless and precipitated (as it seems to happen so often in science these days, given the mad scramble for funding). For instance, this paper proposes that memory formation has to do with protein transcription in the nucleus of the neuron, while this paper states that memories are stored in microtubules. For now, it seems things are all over the place, which doesn't inspire much confidence.
The entire discussion about whether the discovery of material correlates of memory access contradicts or reinforces the non-materialist hypotheses is insignificant in face of the broader problem where it is contained: The problem of explaining consciousness itself in terms of physical metabolism. This broader problem may be unsolvable.