OPTOKINETIC AND PURSUIT SYSTEM - A CASE-REPORT

Citation
Uj. Ilg et al., OPTOKINETIC AND PURSUIT SYSTEM - A CASE-REPORT, Behavioural brain research, 57(1), 1993, pp. 21-29
Citations number
39
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
01664328
Volume
57
Issue
1
Year of publication
1993
Pages
21 - 29
Database
ISI
SICI code
0166-4328(1993)57:1<21:OAPS-A>2.0.ZU;2-P
Abstract
Several studies have demonstrated the importance of the pretectal Nucl eus of the Optic Tract (NOT) and the Dorsal Terminal Nucleus of the ac cessory optic system (DTN) for the generation of horizontal optokineti c nystagmus (OKN). Although single unit data from trained rhesus monke y NOT/DTN cells are available it is still unclear if there is a link b etween the pursuit and the optokinetic system at this level of motion analysis. In order to address the question whether the NOT/DTN is impo rtant for the optokinetic as well as the pursuit system an electrolyti c lesion was placed where NOT/DTN activity was recorded previously. Th e monkey was tested on optokinetic and pursuit paradigms. Immediately following the lesion the monkey performed a spontaneous nystagmus with slow phases directed away from the lesioned side. This spontaneous ny stagmus persisted even during optokinetic stimulation in the opposite direction. During the first week postlesion the spontaneous nystagmus disappeared and the monkey regained the ability to perform optokinetic nystagmus toward the lesioned side. The gain of the mean slow phase e ye velocity was, however, largely reduced for this stimulus direction. The onset of OKN following the onset of optokinetic stimulation was n ot affected by the lesion. During smooth pursuit the mean eve velocity was more reduced for pursuit towards the lesioned side. The resulting position error was compensated by an increase in the number of catch- up saccades. In addition to the confirmation of the well-known directi onal deficits of the optokinetic system caused by a lesion of the pret ectum, a directional deficit in the pursuit system was demonstrated.