Complementary filtering in the central nervous system

Abstract

Complementary filtering theory is used to explain the behaviour of three mammalian reflexes, all concerned with the measurement of head angular movement and with reflex control of eye movements. A short explanation of complementary filtering theory is followed by a discussion of the vestibulo-ocular reflex. Experimental results are presented, indicating the frequency response of this system and a transfer function is derived. The optokinetic reflex is then described, and results of further experiments are used to obtain a transfer function for these two reflexes combined. A transfer function is then obtained for the optokinetic reflex alone. This is compared with that obtained for the vestibulo-ocular reflex, and the two are found to be consistent with complementary filtering theory. This theory is then used to predict the dynamics of the cervico-ocular reflex, and these predictions are compared with the experimental results of others. Complementary filtering theory is found to conform well with all the experimental results described, and it is therefore claimed that the three reflexes combined may be regarded as a complementary filter.