Am J Psychiatry 1997; 154:156-164
Copyright © 1997 by American Psychiatric Association
Modifiable neuronal connections: an overview for psychiatrists
KJ Jeffery and IC Reid
Department of Anatomy and Developmental Biology, University College London, U.K. kate@anatomy.ucl.ac.uk
Synaptic plasticity is currently the target of much neurobiological
research, because it is thought to play an important role in brain function
(particularly memory formation). However, it has attracted little attention
from psychiatrists to date despite accumulating evidence that links it to
various clinical syndromes, including amnesia and possibly psychosis. The
purpose of this article is to present an overview of the two major arms of
synaptic plasticity research- theoretical (the field of neural network
modeling) and neurobiological (long-term potentiation). Artificial neural
networks are a class of theoretical model that has been developed with the
aim of understanding how information could, in principle, be represented by
large numbers of interconnected and relatively simple units. Over the past
few decades, several theoretical accounts of information-processing
mechanisms have been developed, and these are briefly reviewed. The
principle common to representation formation in nearly all neural networks
is that of "associability"-the idea that streams of information are
combined by forming, strengthening, or pruning connections between them to
form new representations that can later be retrieved. Associability also
lies at the heart of psychological theories of information storage in the
brain. Research into associability has directed the attention of many
experimenters toward the possible biological correlates of such mechanisms.
Of particular interest is the recent discovery that some neurons appear to
possess connections of modifiable strength. The implications of this
finding for psychiatry are discussed in relation to representational
disorders such as delusions and amnesia.
