LICKING BEHAVIOR IN THE RAT - MEASUREMENT AND SITUATIONAL CONTROL OF LICKING FREQUENCY

Lick sensors are versatile instruments that are routinely used in beha vioral and neuroscience research involving fluid ingestion in the rat. There are three different types of sensors: electrical, optical and f orce sensors. They differ in the exact moment of activation during the tongue protrusion/retraction cycle. Precautions in the use of each ty pe of sensor are discussed. Adequate lick detection requires restricti on of access to the water source to the tongue of the animal. It appea rs that drinking configurations that fulfill this task may affect the modal licking frequency. Increasing the amount of tongue travel that i s needed to reach the drinking tube or water surface, decreases the li cking frequency. The licking frequency can be manipulated between abou t 7.5 and 4 Hz. Therefore, if 'invariant' licking/lapping frequencies are observed, this is not so much the manifestation of a rigid output of a central pattern generator, but more the consequence of similarity in the effects of the employed drinking configurations. Applications of lick sensors in behavioral and neuroscience research are briefly di scussed. (C) 1998 Elsevier Science Ltd. All rights reserved.