Biology

Dr. Tiago Marques
Champalimaud Centre for the Unknown, Lisbon

The neocortex is composed of reciprocally connected, hierarchically organized areas. Understanding how the neocortex processes information requires studying its organization as well as its function during behavior. In this talk I will describe two approaches, which we have developed, to study the cortical circuits involved in visual perception in the mouse.

First, we characterized the functional organization of cortical feedback. For this we measured retinotopic specificity in inputs from the lateromedial visual area in mouse primary visual cortex (V1) by mapping receptive fields in feedback boutons and relating them to those of neurons in their vicinity. We found that feedback inputs targeted, on average, retinotopically matched locations in V1, but many of them relayed distal visual information depending on their functional tuning properties.

In a different project, we developed a novel head-fixed discrimination task in which mice reported the perceived direction of motion from random dot kinetograms. Recordings in layers 2/3 of V1 revealed the existence of a population of highly direction-selective neurons with responses modulated by stimulus coherence. V1 activity played a key role in motion discrimination since its inactivation led to an impairment in performance.