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Homeostatic plasticity and ocular dominance diversity can account for the differential expansion of the left- and right-eye receptive fields of V1 neurons after monocular retinal lesions
Citation
Young, JM and Wimmer, K and Calford, MB and Obermayer, K, Homeostatic plasticity and ocular dominance diversity can account for the differential expansion of the left- and right-eye receptive fields of V1 neurons after monocular retinal lesions, Proceedings of Cosyne 2007, pp. 247. (2007) [Conference Extract]
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Abstract
When V1 neurons are subjected to a loss of subcortically-mediated feedforward input they respond by
expanding their receptive fields, apparently due to an increase in the efficacy of the input arriving via
their intracortical connections. This is likely to reflect a generalised strategy that allows neurons to
recover from deficiencies in synaptic drive by uniformly potentiating subthreshold input connections to
suprathreshold levels at which these connections can engage in activity-dependent Hebbian competition. It is plausible that this sub- to supra-threshold transformation is achieved by some kind of
homeostatic modulation of gain, where the efficacies of all synapses are scaled such that excitatory
neurons become more responsive and inhibitory neurons become less responsive to input (effectively
producing disinhibition). However, after being partially deafferented by a monocular retinal lesion,
binocular neurons in V1 appear to show receptive field expansion of their lesioned eye receptive fields
only. Such a bias appears to be inconsistent with the hypothesis that a non synapse-specific form of
homeostatic plasticity underlies this receptive field expansion. In this study we examined experimental
results from monocular lesion experiments and compared them to the behaviour of a network model of
V1. The feedforward and horizontal connectivity of each modeled neuron population (or ‘column’) had a
specific ocular bias, and the distribution of ocular dominance within the network was based on in vivo
data. We found that if the modeled columns underwent homeostatic plasticity at an intensity proportional
to their input loss the distribution of the ratios of lesioned eye to non-lesioned eye receptive field
expansion matched the distributions observed in vivo. Our results support the hypothesis that neurons are
able to undergo homeostatic plasticity that is proportional to changes in their total synaptic input. In
addition, the results indicate that the spatial specificity of this plasticity is at least below that of the scale
of ocular dominance columns.
Item Details
Item Type: | Conference Extract |
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Research Division: | Biomedical and Clinical Sciences |
Research Group: | Neurosciences |
Research Field: | Sensory systems |
Objective Division: | Health |
Objective Group: | Clinical health |
Objective Field: | Clinical health not elsewhere classified |
UTAS Author: | Calford, MB (Professor Mike Calford) |
ID Code: | 96902 |
Year Published: | 2007 |
Deposited By: | Division of the Provost |
Deposited On: | 2014-11-25 |
Last Modified: | 2014-11-25 |
Downloads: | 0 |
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