A DEFECTIVE CONTROL OF SMALL-AMPLITUDE MOVEMENTS IN MONKEYS WITH GLOBUS-PALLIDUS LESIONS - AN EXPERIMENTAL-STUDY ON ONE-COMPONENT OF PALLIDAL BRADYKINESIA
M. Alamy et al., A DEFECTIVE CONTROL OF SMALL-AMPLITUDE MOVEMENTS IN MONKEYS WITH GLOBUS-PALLIDUS LESIONS - AN EXPERIMENTAL-STUDY ON ONE-COMPONENT OF PALLIDAL BRADYKINESIA, Behavioural brain research, 72(1-2), 1995, pp. 57-62
The effects of globus pallidus (GP) lesion were examined in two monkey
s trained to perform a visually guided pointing movement in simple and
choice reaction time tasks involving small and large amplitude moveme
nts. The reaction time (RT) and the movement time (MT) were measured.
The Y-axis error (EY) was also analyzed in order to assess the movemen
t accuracy. Unilateral GP lesion was made by locally injecting an exci
tatory amino acid, quisqualic acid. GP lesion led to little change in
the RTs (simple and choice RTs) and in the EY, whereas a large increas
e in the MT occurred. The MT impairments seem to have been correlated
with the movement amplitude, since they were larger in the case of sma
ll-amplitude than large-amplitude movements. These results suggest tha
t the GP may be involved in the control of small-amplitude rather than
large-amplitude movements. As various studies have shown that proprio
ceptive cues are more strongly involved in the control of discrete tha
n large-amplitude movements, the MT deficit, i.e., the bradykinesia ob
served here, may reflect a defective integration of proprioceptive inf
ormation occurring after GP lesion.