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REPRESENTATIONS DE SCENES TACTILES COMPLEXES DANS LA BOUCLE THALAMO-CORTICALE DU SYSTEME VIBRISSAL

Abstract : Rats explore their environment with their whiskers generating complex sequences of contacts across the whiskerpad. To study the integration of these multi-vibrissal patterns by the primary somatosensory cortex, we developed a 24 whisker stimulator. With this tool we showed that the spatial structure of cortical receptive fields is stimulus-dependent and can be modulated by the direction of whisker deflection. Cortical responses are also selective to global emergent properties of the stimulus: we observed that independently of the direction selectivity to the deflection of the principal whisker, cortical neurons are selective to the direction of an apparent motion generated by the sequential stimulation of 24 whiskers. Since multi-whisker integration has been reported in the VPM thalamic nucleus, the main source of inputs to the cortex, we hypothesized that sub-cortical mechanisms could contribute to cortical multi-vibrissal integration. We observed that VPM neurons are selectivity to global movement, although in smaller proportions. Thus, this selectivity could emerge at the level of the thalamo-cortical loop and could be amplified in the cortex. Indeed, through electrophysiological recordings in the thalamus combined to the inactivation of the cortico-thalamic pathway, we observed a significant decrease in the selectivity to global apparent motion of VPM neurons. Multi-vibrissal integration would be carried out by the joint action of the thalamo-cortical loop and intra-cortical connectivity. We showed that the selectivity is absent at the trigeminal ganglion, the first input stage, but a contribution of mesencephalic stages of the afferent pathway remains to be explored.
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https://theses.hal.science/tel-00662452
Contributor : Julie Le Cam Connect in order to contact the contributor
Submitted on : Tuesday, January 24, 2012 - 11:07:08 AM
Last modification on : Saturday, July 2, 2022 - 3:52:14 AM
Long-term archiving on: : Wednesday, December 14, 2016 - 12:31:45 AM

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  • HAL Id : tel-00662452, version 1

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Julie Le Cam. REPRESENTATIONS DE SCENES TACTILES COMPLEXES DANS LA BOUCLE THALAMO-CORTICALE DU SYSTEME VIBRISSAL. Neurosciences. Université Pierre et Marie Curie - Paris VI, 2010. Français. ⟨NNT : ⟩. ⟨tel-00662452⟩

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