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Abstract #1822

Resolving activity suppression in the rat visual pathway using fMRI combined with lesions

Rita Gil1, Mafalda Valente1, Alfonso Renart1, and Noam Shemesh1
1Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon PT, Lisbon, Portugal


Monocular visual stimulation with short inter-stimulus intervals (ISIs) evokes (i) negative BOLD responses (NBRs) in the contralateral superior colliculus (cSC), and (ii) positive BOLD responses (PBRs) in the ipsilateral superior colliculus (iSC). This pattern suggests a potential "push-pull" mechanism between SCs possibly evoked by (mostly inhibitory) tectotectal projections. Here, we mapped activity in the entire visual pathway using fMRI, and modulated cSC inputs through lesions in visual cortex and SC to dissect collicular communication mechanisms. While, cortical context potentiated a putative “push-pull” mechanism, further silencing of iSC resulted in PBRs in cSC, suggesting that iSC exerts suppression on cSC.

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