Paper on experience-dependent cortical plasticity

[Lubica Benuskova]

Dear Connectionists,

the preprint of the following article: 

"Theory for normal and impaired experience-dependent plasticity 
in neocortex of adult rats" 

Proc. Natl. Acad. Sci. USA 98(5): 2797-2802, 2001.
by Benuskova L, Rema V, Armstrong-James M and Ebner FF  

can be downloaded from 
http://www.dcs.elf.stuba.sk/~benus/#publications

Abstract:
We model experience-dependent plasticity in the cortical representation
of whiskers (the barrel cortex) in normal adult rats, and in adult rats
that were prenatally exposed to alcohol. Prenatal exposure to alcohol
(PAE) caused marked deficits in experience-dependent plasticity in a
cortical barrel-column. Cortical plasticity was induced by trimming all
whiskers on one side of the face except two. This manipulation produces
high activity from the intact whiskers which contrasts with low activity
from the cut whiskers while avoiding any nerve damage. By a computational
model we show that the evolution of neuronal responses in a single
barrel-column following this sensory bias is consistent with the synaptic
modifications that follow the rules of the Bienenstock, Cooper and Munro
(BCM) theory. The BCM theory postulates that a neuron possesses a moving
synaptic modification threshold, $\theta_M$, which dictates whether the
neuron's activity at any given instant will lead to strengthening or
weakening of its input synapses. The current value of $\theta_M$ changes
proportionally to the square of the neuron's activity averaged over some
recent past. In the model of alcohol impaired cortex, the effective
$\theta_M$ has been set to a level unattainable by the depressed levels
of cortical activity. Abnormally low activity leads to ``impaired''
synaptic plasticity that is consistent with experimental findings.
Based on experimental and computational results we discuss how elevated
$\theta_M$ may be related to the abnormally low expression of
N-methyl-D-aspartate receptors (NMDARs) and the membrane
translocation of Ca$^{2+}$/calmodulin-dependent protein kinase II
(CaMKII) in adult rat cortex subjected to prenatal alcohol exposure.


Lubica Benuskova, PhD
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Slovak Technical University
Dept. of Computer Science and Engineering
Ilkovicova 3, 812 19 Bratislava 1, Slovakia
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Phone: (+421 7) 602 91 696    Fax: (+421 7) 654 20 587
E-mail: benus at elf.stuba.sk, benus at dcs.elf.stuba.sk
http://www.dcs.elf.stuba.sk/~benus