EFFECT OF OLIVOCOCHLEAR BUNDLE LESION ON LOCOMOTOR-ACTIVITY IN RATS

This study was conducted to investigate the effect of olivocochlear bu ndle (OCB) lesion on spontaneous locomotor activity in Wistar rats. Th e OCB is an auditory efferent pathway which originates from the superi or olivary complex in the brainstem and terminates within the cochlea. It has an inhibitory effect on the auditory end organs. In the presen t study, the OCB was damaged at the floor of the fourth ventricle usin g radiofrequency current. The rats' locomotor activities were then mon itored weekly for 2 months using an automated Digiscan activity monito r system. Six behavioral variables were collected and analyzed: horizo ntal activity (HA), total distance (TD), movement time (MT), vertical activity (VA), stereotypy count (SC), and margin time (MGT). Significa nt time-dependent increases were noted for HA, TD, VA, and SC followin g OCB lesion. These results of increasing exploratory and stereotyped behaviors may be caused by the rat experiencing more auditory stimulat ion than before due to OCB dysfunction and may cause the rat to become more curious to explore its surroundings. (C) 1998 Elsevier Science I nc.