Counter-rolling after regional destruction of the saccule by laser spot irradiation in the guinea pig.

Abstract

Destruction of the anterior one-third of the right saccule in the guinea pig resulted in a marked eye deviation simultaneously towards the ear and downward on the operated side and a marked upward eye deviation on the non-operated side in the standard head position. During head inclination towards the operated side, both eyes showed a disturbed ocular counter-rolling (OCR). The disturbance of OCR was more severe in the eye on the operated side than in the eye on the non-operated side. Brief interpretation about eye position in the standard head position in the regional destructive group showed that the eye ball on the operated side showed a marked deviation simultaneously upward and towards the ear, while the eye ball on the non-operated side showed an upward deviation on the 1st and 3rd days after the operation. OCR after regional destruction was seen as follows: During head inclination towards the operated side, both eyes showed disturbed OCR. The disturbance of OCR was more severe in the eye on the operated side. Most animals in our experiment showed this disturbed OCR which was compensated and normalized by the third postoperative week; relatively shorter (faster) than the total destruction. These results suggest that when the head is inclined around its longer axis, the saccule on the side of head inclination plays a principal role in the otolith-ocular reflex.