biology and psychology
rof at maths.tcd.ie
Thu Sep 19 12:34:33 EST 1996
"Igor Rubets" <ir at axess.com> writes:
>Ruadhan O'Flanagan wrote ...
>> Actually, neurochemical states influence the firing of neurons(viz. the
>> "thoughts" and "feelings" of the subject), and it is that particular
>> influence, or tendency of thoughts, which is the mood itself.
>OK. And in what mood is a man experiencing malnutrition problems?
>And to be serious... I surely agree that when you think of the mood in
>general terms, then yes, it is mainly, if not purely, neurochemical (and
>after that, "neuroelectrical").
>But I don't know of any causal relation between some specific pattern of
>discharge (least to say about some specific neurochemical properties) and
>some certain thought. I myself studied macro and micro electrophysiological
>phenomena (namely, EEG, subcortical macroelectrodes, and single/multiple
>neuron activity recordings) and I never managed to combine PHYSICS (and
>neurophysiology is materialistic, hence physical science) with PSYCHE. I
>can assure you, I'm not the only one who didn't.
Well a full description of how neural firing patterns are related to
thoughts, perceptions, and so on is available from
http://www.maths.tcd.ie/~rof/neuro. All of internal speech, hippocampal
consolidation of long-term memories, emotions, and other mental tricks
>> Your name is stored (mostly) in your temporal lobes.
>OK. But HOW? In what way? Where exactly? Is there or are there some
>specific neuron(s)? Can you specify the "font"? What is the neuron
>discharge pattern for a given "John Doe" and what is the difference between
>the patterns of "Doe" and "Dow" (not if you read those names, of course,
>but if you recall them)?
Ok, well basically, when your ear detects sound at a certain pitch, and
at a certain volume, a characteristic pattern of neurons will fire in the
primary auditory cortex. These will synapse on other neurons, these on
others and so on. Feedback connections to the thalamus ensure that
neurons keep firing for a short time even after the sound was detected.
So if your ear detects a short pattern of sounds, at different frequencies
and volumes, then a characteristic pattern of neurons fire in the primary
sensory area. These will cause other neurons to fire, and those others
and so on. The "neural pathway" of a neuron(as I use the term) consists
of the neurons to which it connects strongly, and the neurons to which
those connect strongly and so on. The pathway from a single neuron would
look sort of like a tree.
When you hear "John Doe!", a characteristic pattern of neurons fire,
each of which has a pathway. The neural pattern representing "John Doe"
consists of the overlap of the pathways of those neurons(i.e. all the
neurons which are common to every pathway). This is because each of
the neurons in this pattern will be strongly stimulated when you hear
of John Doe.
For the sake of convenience, I call the neurons which fire initially as the
first neuronal level, which connects to the second level, and so on.
It's altogether possible that the overlap of the first level neurons
which respond to "John Doe" will be very small, in which case "John Doe"
is a sound which is not very well represented in the person's mind.
However, if the sound is heard frequently, Hebbian learning mechanisms
will cause the pathways to tend to coalesce, and so the overlap will
grow, and John Doe will be better represented in the person's mind.
This is a very crude simplification of the process involved, but it
should give an idea of how sounds are recognised and what neural
firing pattern mean what and so on.
I'd be very interested in comments/criticism of this model.
Here's the abstract of my paper, for those interested:
Neural Correlate of Conscious Phenomena
This is a proposed model of the neural basis of the psychological events
which constitute the 'consciousness' of a person. It is proposed that by
describing the properties of neurons and large networks of neurons, and by
applying these properties to the structure of the brain and its sensory
inputs, the mechanisms underlying the functions of each part of the brain
can be explained, and the behaviour of the brain understood. It is futher
proposed that the psychological phenomena which make up our own subjective
feelings and thoughts relate directly to neurological events, and the
properties and limitations of those thoughts and feelings can be understood
by examining the mechanisms which give rise to them.
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