1. The aim of the present thesis is to examine. from the point of view of the control theorist. the possibility of formalisation of the functioning of the nervous and hormonal systems of higher mammals, and to advance cybernetic models for some aspects of the operation of these systems. 2. A general control model is described for the interaction of the biological organism with its environment and is supported by a reinterpretation of some physiological phenomena in the terms of the model. 3. Two formal models of the pre-cortical segment of the visual system of the cat are proposed. The first model is expressed in terms of mathematical logic and serves as a guide to a second, more accurate and exhaustive, approximation which makes use of continuous operations.