Cortical origin of functional recovery in the somatosensory cortex of the adult mouse after thalamic lesion

Authors

  • Alexandre Croquelois,

    1. Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Rue du Bugnon 9, CH-1005 Lausanne, Switzerland
    2. Neurology Department, Centre Hospitalier Universitaire Vaudois (CHUV), Rue du Bugnon 46, 1011 Lausanne, Switzerland
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  • Gilles Bronchti,

    1. Département Chimie-Biologie, Université du Québec à Trois-Rivières, Blvd des Forges 3351, C.P. 500, Trois-Rivières G9A 5H7 Canada
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  • Egbert Welker

    1. Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Rue du Bugnon 9, CH-1005 Lausanne, Switzerland
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Dr Alexandre Croquelois, 1as above.
E-mail: alexandre.croquelois@unil.ch

Abstract

To study the degree and time course of the functional recovery in the somatosensory cortex (SI) after an excitotoxic lesion in the adult mouse thalamus, metabolic activity was determined in SI at various times points post-lesion. Immediately after the lesion, metabolic activity in the thalamically deafferented part of SI was at its lowest value but increased progressively at subsequent time points. This was seen in all cortical layers; however, layers I and Vb recovered more rapidly than layers II, III, IV, Va and VI. Removal of the mystacial whiskers corresponding to the deafferented area, 5 weeks after cortical recovery, produced a subsequent 32% drop in metabolic activity, demonstrating peripheral sensory activation of this part of the cortex. Tracing experiments revealed that the deafferented cortex did not receive a novel thalamic input but that cortico-cortical and contralateral barrel cortex projections to this area were reinforced. We conclude that the cortical functional recovery after a thalamic lesion is, at least partially, due to modified cortico-cortical and callosal projections to the deafferented cortical area.

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