Innate and Learned Components in a Simple Visuo-Motor Reflex

In this review a model is proposed that explains the differences in a simple visuo-motor reflex, the optokinetic reflex (OKR), in various mammals by the specific interactions between retinal and cortical projections to the nucleus of the optic tract (NOT) in the pretectum. The model is based on the following assumptions. 1.A genetically prespecified retinal input reaches the NOT first during ontogeny.2.Thereafter information flow via cortical connections is accepted only if it agrees with the complements of the retinal input.3.After the cortico-pretectal connections have been established, the retino-pretectal connections gradually lose their influence and are replaced by cortical afferents.This model explains why after the loss of visual cortex the optokinetic reflex is much weaker and asymmetric and why wrong instructions during early visual experience lead to a loss of binocularity in the NOT and as a consequence to an impaired and asymmetric OKR.