Event:

The superficial layers of the medial entorhinal cortex (MEC) contain spatially selective neurons that are essential for spatial navigation. These specialized neurons include grid cells, border cells, head direction cells and irregular spatially selective cells. A key step in understanding the neuronal network in the superficial layers of the MEC is to determine the anatomical, molecular and electrophysiological features with which MEC neurons can be classified. In the first part of my talk, I will describe an experiment combining tetrode recordings and optogenetics in behaving mice to identify and characterize the firing patterns of parvalbumin-expressing interneurons. Contrary to the predictions of some grid cell computational models, we found that parvalbumin-expressing interneurons did not express clear grid cell periodicity. In the second part of the talk, I will present data suggesting that principal neurons in superficial layers of the MEC can be classified into two groups based on their propensity to fire spike doublets at 125-250 Hz. The two groups, labelled ”bursty” and ”non-bursty” neurons, differed in their spike waveform, inter-spike interval adaptation, and excitatory coupling to GABAergic interneurons. Importantly, neurons in the two groups encoded preferentially different types of spatial information, indicating that they play distinct roles in the MEC network.