GABAergic neurons play an essential role in governing the timing of principal neuron firing. My lab has focused for long on studying functional properties of GABAergic neurons in mice by taking advantage of genetic modifications that would reduce the recruitment of defined GABAergic neurons preferentially in the hippocampal formation, and investigate the consequences thereof for spatial coding and memory.

             Neocortical GABAergic neurons have long been considered “interneurons”, that is their range of inhibition is confined to local networks. We discovered that this is not the case: a subpopulation are GABAergic “projection” neurons that inhibit preferentially GABAergic neurons thereby causing disinhibition in the target area. The functional study of these neurons, be that in the slice preparation or in freely mice has been heavily aided by the use of optogenetic approaches. I will discuss ongoing projects in the lab that focus on GABAergic projection neurons in health and disease.

             Finally, I will present and discuss work focusing on the medial and lateral entorhinal cortex and their participation in spatial- and non-spatial coding. Here too I will highlight data on GABAergic neurons (i.e. fast-spiking cells), raising the question as to their coding in simple and complex environments.