Periodic Reporting for period 1 - RhinalMultiSense (Circuits for multisensory integration in the perirhinal cortex)
Reporting period: 2020-05-01 to 2022-04-30
The perirhinal cortex is a high order association area involved in object recognition. It receives information from all sensory modalities. The aim of the RhinalMultiSense project was to unveil the circuits of perirhinal cortex involved in sensory and multisensory processing. To achieve this goal, I combined neuroanatomical tracing to map the sensory inputs of perirhinal cortex along its rostro-caudal axis. These experiments revealed the origin of sensory inputs to perirhinal cortex and their topographic organization. I then used in vitro electrophysiology coupled with optogenetics to test the circuits involved in processing tactile inputs in perirhinal cortex.
The results of RhinalMultiSense will be fundamental to resolve the mechanisms of multisensory object recognition in the cortex.
I performed in vitro electrophysiological recordings couped with optogenetics to test the connectivity between primary somatosensory cortex and perirhinal cortex. I found that somatosensory inputs target preferentially the deep layers in both cerebral hemispheres. Somatosensory inputs had a strong and long-lasting inhibitory component. I found that the largest population of inhibitory neurons in perirhinal cortex does not express any of the known molecular markers for cortical interneurons. I described a viral approach to label these neurons that will allow me to test whether these inhibitory cells mediate the inhibition elicited by somatosensory inputs.
I presented results of the RhinalMultiSense project at the FENS meeting in 2020, at a symposium at the Nencki Institute in Poland, and at a Symposium at the Department of Biotechnology of the University of Pavia, Italy. More information on RhinalMultiSense is available at https://nigrolab.com.
So far, I published two open access peer-reviewed article and one preprint in biorxiv. Another manuscript is currently in preparation and will be submitted to an open access journal and uploaded in biorxiv.
RhinalMultiSense provides the first evidence of an inhibitory mechanism in perirhinal cortex gating sensory inputs. Indeed, optogenetic stimulation of somatosensory inputs elicit strong inhibition in the perirhinal cortex of both hemispheres.
These results are currently guiding the efforts in my newly funded Research Group to unveil the mechanisms of sensory and multisensory processing by large neuronal populations in perirhinal cortex.