Eye movements in monkeys with local dopamine depletion in the caudate nucleus. II. Deficits in voluntary saccades.
Unilateral infusion of MPTP into the monkey caudate nucleus produced deficits in task-specific saccades, in addition to the deficits in spontaneous eye movements (preceding article). We trained three monkeys to perform two kinds of saccade tasks: (1) saccade task for eliciting visually guided saccades and (2) delayed saccade task for eliciting memory-guided saccades. After the MPTP infusion, dopaminergic function, estimated by tyrosine hydroxylase (TH) immunoreactivity, was shown to be decreased locally around the infusion site at the head-body junction of the caudate. We found that the deficits were prominent in the saccades directed to the side contralateral to the infusion (contralateral saccades). Memory-guided saccades were sometimes misdirected to the ipsilateral side even when the cue stimulus was presented on the contralateral side. Among the parameters of saccades, a selective change was found in the saccade latency: the latency was prolonged consistently in contralateral memory-guided saccades. The amplitude and velocity of saccades decreased in contralateral saccades, either memory guided or visually guided. The duration of saccades tended to increase in visually-guided saccades and memory-guided saccades, in both directions. Only one monkey, in which the decrease in TH activity included a large part of the putamen and the head of the caudate, showed prolongation of manual reaction time for lever release.
Kori
A
A
Department of Biological Control System, National Institute for Physiological Sciences, Okazaki, Japan.
Miyashita
N
N
Kato
M
M
Hikosaka
O
O
Usui
S
S
Matsumura
M
M
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000172:deficiency*; D005133:Eye Movements; D006225:Hand; D008251:Macaca; D008297:Male; D009068:Movement / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects; D012438:Saccades / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology
D012965:Sodium Chloride; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D004298:Dopamine