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Ferezou, I.

Publications and source records attributed to Ferezou, I..

3 recordsLinked to original sources

Operant conditioning of cortical waves through a brain-machine interface

At the surface of the cerebral cortex, the dynamics of brain activity at the mesoscopic scale are characterized by waves of synchronized neuronal activity. These waves have been shown to impact the processing of sensory information, but can they be actively shaped by the subject in a goal directed manner? To address this question, we designed a fast widefield optical brain-machine interface for mice that can detect and reinforce individual traveling waves, which follow a specific displacement at the surface of the somatosensory cortex. Trained mice learned to generate these Conditioned Waves, which became progressively more stereotyped. The Conditioned Waves resulted from a reshaping of the cortical activity associated with limb movements, which included a sharp pre-movement cortical suppression that emerged with learning. Our work demonstrates that traveling cortical waves of neuronal activity can be subject to operant control. It provides evidence for the plasticity and functional relevance of large-scale cortical dynamics, and establishes a new paradigm for manipulating mesoscale brain activity.

neuroscience↗

Nonlinear collision between anisotropic propagating waves in mouse somatosensory cortex

How does cellular organization shape the spatio-temporal patterns of activity in the cortex while processing sensory information? After measuring the propagation of activity in the mouse primary somatosensory cortex (S1) in response to single whisker deflections with Voltage Sensitive Dye (VSD) imaging, we developed a two dimensional mean field model of S1. We observed that, for strong enough excitatory cortical interactions, whisker deflections generate a propagating wave in S1. We developed an inversion method that reconstructs model parameters from VSD data, revealing that a spatially heterogeneous organization of synaptic strengths between pyramidal neurons in S1 is likely to be responsible for the anisotropic spatio-temporal patterns of activity measured experimentally. Finally, we report that two consecutive stimuli activating different spatial locations in S1 generate two waves which collide sub-linearly. In the model, such sub-linear interaction is explained by a lower sensitivity to external perturbations of neural networks during activated states.

neuroscience↗

Biphasic impact of prenatal inflammation and macrophage depletion on the wiring of neocortical inhibitory circuits

The etiology of neurodevelopmental disorders is linked to defects in Parvalbumin (PV)-expressing cortical interneurons and to prenatal immune challenges. Mouse models of maternal immune activation (MIA) and microglia deficits increase the postnatal density of PV interneurons, raising the question of their functional integration. Here, we show that MIA and embryonic depletion of macrophages including microglia, have a two-step impact on PV interneurons wiring onto their excitatory target neurons in the barrel cortex. In adults, both challenges reduced the inhibitory drive from PV interneurons, as reported in neurodevelopmental disorders. In juveniles, however, we found an increased density of PV neurons, an enhanced strength of unitary connections onto excitatory cells and an aberrant horizontal inhibition with a reduced lateral propagation of sensory inputs in vivo. Our results provide a novel framework for understanding the impact of prenatal immune challenges onto the developmental trajectory of inhibitory circuits that leads to pathological brain wiring.

neuroscience↗