The reorganization of neural activity that takes place after stroke is
of paramount importance in producing functional recovery.
A.
From.
APStracts 4:0244N, 1997.
ABSTRACT
Experimental stroke models have suggested that this reorganization may
have two phases, but physiology alone cannot fully resolve what causes each
phase. Computer modeling suggests that these phases might involve an initial
change in dynamics occurring immediately, followed by synaptic plasticity. We
combined physiological recording from macaque middle temporal cortex (area MT)
with a neural network computer model to examine this first phase of altered
cortical function following a small, experimentally induced cortical lesion.
Major receptive field changes seen in the first few days postlesion included
both expansion and contraction of receptive fields. While only expansion could
be reproduced in an initial model, addition of inhibitory interneuron loss in
a ring around the primary ablation, suggested by immunohistochemical
examination, permitted contraction to be replicated as well. We therefore
predict that this immunochemical observation reflects an immediate extension
of the lesion rather than a late response. Additionally, our model
successfully predicted a correlation between increased firing rate and RF
size. Our model suggests that activation dynamics alone, without anatomical
remodeling, can cause the large receptive field changes that allow the rapid
behavioral recovery seen following middle temporal lesions.
Received 20 June 1997; accepted in final form 10 September 1997.
APS Manuscript Number J514-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 7 October 1997