Non-local Nature of Habituation in a Rotifer and Protozoan

Abstract

HABITUATION, defined as a “waning of a response as a result of repeated stimulation”¹, can be considered to be a form of learning if fatigue, injury and local sensory adaptation can be ruled out. This is the case when an organism shows the same behaviour response to a different or more intense stimulus after habituation. The usual way to ascertain whether there is local sensory adaptation is by recording electrically the relevant sensory pathways; this is often quite difficult, either because the nerves are too small or are too numerous to record from. It is possible to design behavioural experiments to test for non-local habituation; among the invertebrates¹, however, this is only possessed by planarians².