A mutant with bilateral whisker to barrel inputs unveils somatosensory mapping rules in the cerebral cortex

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Renier, Nicolas, M | Dominici, Chloé, M | Erzurumlu, Reha, M | Kratochwil, Claudius F. | Rijli, Filippo, M | Gaspar, Patricia, M | Chédotal, Alain, M

Edité par CCSD ; eLife Sciences Publication -

International audience. In mammals, tactile information is mapped topographically onto the contralateral side of the brain in the primary somatosensory cortex (S1). Here we describe that in Robo3 mouse mutants a sizeable fraction of the trigemino-thalamic inputs project ipsilaterally rather than contralaterally. The resulting mixture of crossed and uncrossed sensory inputs creates bilateral whisker maps in the thalamus and cortex. Surprisingly, these maps are segregated resulting in a duplication of whisker representations and a doubling of the number of barrels without changes of the S1 size. Sensory deprivation shows competitive interactions between the ipsi/contralateral whisker maps. This study reveals that the somatosensory system can form a somatotopic map to integrate bilateral sensory inputs but organizes the maps in a different way than in the visual, or auditory systems. Therefore, while the molecular pre-patterning constrains their orientation and position, the preservation of the continuity of inputs defines the layout of the somatosensory maps.

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