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Cross‐modal plasticity of the corticothalamic circuits in rats enucleated on the first postnatal day
Author(s) -
Négyessy László,
Gál Viktor,
Farkas Tamás,
Toldi József
Publication year - 2000
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2000.00057.x
Subject(s) - neuroscience , enucleation , somatosensory system , geniculate , anterograde tracing , anatomy , visual cortex , postsynaptic potential , thalamus , eye enucleation , cortex (anatomy) , lateral geniculate nucleus , biology , central nervous system , nucleus , biochemistry , genetics , receptor
Reorganization of the reciprocal corticothalamic connections was studied as a possible anatomical substrate of the cross‐modal compensation of the missing visual input of the visual cortex by somatosensory‐evoked activities in neonatally enucleated rats. The use of quantitative retrograde tract‐tracing techniques revealed that the contribution of the lateral posterior thalamic nucleus (LP) is significantly increased following enucleation, while that of the dorsolateral geniculate and the lateral dorsal nuclei is decreased in the thalamocortical afferentation of a region in visual cortical area 17. In contrast with the control rats, a dense terminal arborization of afferents was labelled in the LP after the injection of anterograde tracer into the barrel cortex of the enucleated rats. The injection of anterograde tracer into the visual cortex also demonstrated a massive afferentation into the LP of the enucleated rats. Visual and somatosensory corticothalamic afferents exhibited similar ultrastructural features in the LP after enucleation, but their synaptic organizations differed as regards the diameter of the postsynaptic dendrites. Taken together with the previous observations, these results suggest a central role for the LP in the transmission of the somatosensory‐evoked activities to the visual cortex after early blindness.