mental retardation/neuro connections

Heinz Beck heinz at
Fri Oct 28 11:45:02 EST 1994

Given the large variety of central nervous system pathology that can lead
to mental dysfunction I do not believe there is a single answer to this
question. Dysfunction of transmitter szstems or altered connectivity will
probably affect intellectual function.

For example, migration disorders in cortical regions can lead to mental 
retardation, recurrent seizures, etc. maybe due to altered connectivity
between dystopic neurons and cortical neurons. Altered connectivity has also
been implied in psychiatric disorders like schizophrenia (I remember an
article by Conrad and Scheibel a few years ago).

On the other hand, sheer neuron mass is probably not the only determinant of
intellectual functioning since we have some experience with hemispherectomies
performed for rasmussens encephalitis. Most of these children do quite well
postoperatively and can sometimes attend normal schools in spite of more 
functions having to `share` less neurons. This happens only if the children
are young enough, presumably the CNS can show more plasticity and adapt to 
decreased neuronal mass.

With regard to the anxiety you would similarly probably have to discriminate
between patients with different pathophysiology. Anxiety might be related
to disturbances in neurotransmitter systems, i.e. noradrenaline, serotonin 
which a clinical neuropharmacologist dealing with anxiety disorders could
tell you all about. I would agree completely with Kevin`s posting on this count.

Greetings, Heinz

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