BEHAVIORAL DEFICITS FOLLOWING LOCALIZED LESIONS OF THE INFERIOR OLIVE

picture of Jensen White presenting his/her poster: BEHAVIORAL DEFICITS FOLLOWING LOCALIZED LESIONS OF THE INFERIOR OLIVE

Jensen White , AR Gibson, KM Horn, A Deep, MR Heusser

BEHAVIORAL DEFICITS FOLLOWING LOCALIZED LESIONS OF THE INFERIOR OLIVE

The inferior olive (IO) is located in the medulla oblongata, the lower section of the brain stem. It is composed of three major subnuclei: the rostral dorsal accessory olive (rDAO), the rostral medial accessory olive (rMAO) and the principal olive (PO). The IO provides input exclusively to the cerebellum by means of climbing fibers. The cerebellum itself is well known for its role in motor adaptation, coordination, and timing. Damage to the IO removes climbing fiber input to the cerebellum, which affects the cerebellum’s ability to properly function. Therefore, an olivary lesion to any of the subnuclei produces marked behavioral deficits. In the present experiment three adult males cats were trained for a period of 2-8 weeks in two tasks: a stationary reach-to-grasp task and a three meter repeated shuttle task. Following training, a 250nl kainic acid lesion was performed selectively to specific olivary substructures and behavioral performance on these tasks was reassessed. The cats were then sacrificed and their brains were sectioned parasagitally at intervals of 40µm. A cresyl violet Nissl stain of these sections was utilized to determine lesion extent and for reconstructive anatomy. It was found that, unlike lesions of other brain structures, those to the IO produce a unique pattern of progressive movement ataxia. Rather than showing initial recovery and long-term stabilization, the lesioned cats instead showed initial recovery with long-term debilitation of motor coordination. What more, we concluded that the progression of the resulting ataxia depends upon the extent of the lesion to the IO, with damage localized to a specific subdivisions producing notably less drastic results. Finally, it was observed that there were slight differences in motor deficits following lesions to specific subnuclei.

Funding for this research was provided by HHMI 52006942 and the Barrow Neurological Foundation.

Conference Home | List of Abstracts | Photo Gallery