Connectivity rules of functionally diverse cortical neurons
Ana Inacio – NIH/NIMH Fellow

Résumé : Neuronal connections provide the scaffolding for neuronal function. Revealing the connectivity of
functionally identified individual neurons is necessary to understand how activity patterns emerge and
support behavior. Yet, the brain-wide presynaptic wiring rules that lay the foundation for the functional
selectivity of individual neurons remain largely unexplored. Cortical neurons, even in primary sensory
cortex, are heterogeneous in their selectivity, not only to sensory stimuli but also to multiple aspects of
behavior. To investigate presynaptic connectivity rules underlying the selectivity of pyramidal neurons to
behavioral state in primary somatosensory cortex (S1), we used two-photon calcium imaging,
neuropharmacology, single-cell based monosynaptic input tracing, and optogenetics. We show that
behavioral state-dependent neuronal activity patterns are stable over time. These are not determined by
neuromodulatory inputs but are instead driven by glutamatergic inputs. Analysis of brain-wide presynaptic
networks of individual neurons with distinct behavioral state-dependent activity profiles revealed
characteristic patterns of anatomical input. While both behavioral state-related and unrelated neurons
had a similar pattern of local inputs within S1, their long-range glutamatergic inputs differed. Individual
cortical neurons, irrespective of their functional properties, received converging inputs from the main S1-
projecting areas. Yet, neurons that tracked behavioral state received a smaller proportion of motor cortical
inputs and a larger proportion of thalamic inputs. Optogenetic suppression of thalamic inputs reduced
behavioral state-dependent activity in S1, but this activity was not externally driven. Our results revealed
distinct long-range glutamatergic inputs as a substrate for preconfigured network dynamics associated
with behavioral state.

Invitée par Rosa Cossart et Roustem Khazipov

Lundi 23 septembre 2024 à 11h – Salle de conférence de l’Inmed