Cortical development of the visual system of the rat

Abstract

Although rat is commonly used for studying the visual system, the development of spatio-temporal receptive field properties of neurons in its primary visual cortex remains relatively unknown. Extracellular single neuron recordings were thus carried out in anaesthetized newborn rats between postnatal (P) day 15 and 30 and in adult rats. The first neuronal responses evoked by drifting sinusoidal gratings were obtained at P16. From P27-P30 to adulthood, the neurons' optimal temporal frequency significantly increased, whereas the contrast threshold decreased. However, the optimal spatial frequency, spatial resolution and spatial bandwidth were, soon after eye opening, similar to those observed in the adult rat. The differential maturation of receptive field properties is discussed with regard to the functional pathways of the rat visual system.