Visual information processing from extracelular recording in Lateral Geniculate Nucleus (LGN) of the rat.

Abstract

PURPOSE: The lateral geniculate nucleus (LGN) is the main thalamic relay nucleus for the visual information that arrive from the retina to the cortex. The main issue of the present work is the electrophisiological caracterization of the rat LGN and the response of its neurons to complex visual stimuli. METHODS: Extracellular multiunit recordings have been performed in Wistar anesthetized rats stimulated with flases and moving gratings. We have determined the latencies number of spikes and presence of oscillatory activity in the responses evoked by flashes as well as the spatia distribution of these characteristics among the neurons of the LGN. Complex stimuli represented by movin gratings have allowed us to study the behaviour of the neurons as a function of orientation, velocity and spatial frequency of the stimuli. RESULTS: The neuronal response patterns change voth linearly and non-linearly depending on these parameters showing in the majority of the cases an increase in their latency with respect of flash stimulation and oscilation frequencies in all ranges except alpha. CONCLUSION: One key tool for our study has been the variation coeficient of averaged spiking frequency of neuronal population which show us that bars orientation is a very important parameter.