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Saccade-related responses of external pallidal neurons in monkey
S218
14-28
EFFECT OF SUPERIOR COLLICULAR LESION ON ELECTRICALLY-ELICITED SACCADES OF THE FRONTAL EYE FIELD IN MONKEY. MASAO AZUMA, YASUSHI KODAKA AND HISAO SUZUKI, Department of Physiology, Hirosaki University School of Medicine, Hirosaki 036, Japan We studied the effect of lesions of the superior colliculus (SC) on the saccades elicited by focal intracortical microstimulation (ICMS) of the frontal eye field (FEF) in an alert monkey with the head immobilized. ICMSs evoked saccades directing toward the contralateral side with a latency period of 27-65 ms and with the threshold of more than 8pA. The latency was short when the threshold was low. As described previously, the amplitude of the saccades was small at the stimulating sites in the lateral part of the FEF, while it was large in the medial FEF. After the ipsilateral SC lesion by injections of kinic acid, we failed to find any systematic change in the topographic organization of the saccade amplitude. However, both the latency and threshold increased and were 44-77 ms and more than The increase of the latency was resulted not only from the 13 PA, respectively. loss of the low threshold but also from an increase of about 10 ms at each These findings may suggest a role of the SC to facilitate generation of threshold. the cortically induced saccades.
14-29
SACCADE-RELATED MAKOTO
KATO
RESPONSES
and OKIHIDE
OF EXTERNAL
HIKOSAKA.
PALLIDAL
NEURONS IN MONKEY.
National Institute for Phvsioloeical Sciences. Mvodaiii. Okazaki
444, Japan. The basal ganglia contain two types of pathways connecting the input areas (caudate/putamen) (GPi/SNr);
with the output areas
one directly, and the other indirectly (via GPe and/or subthalamic nucleus). The direct pathway (e.g.,caudate-
SNr) acts to disinhibit the target structures (e.g., superior colliculus) to facilitate initiation of movements (e.g.. saccadic eye movement). But the function of the indirect pathway is unclear. We then recorded single cell activities from the GPe in the monkey performing visuo-oculomotor
tasks. Out of 400 GPe neurons recorded were found saccadic (n=64),
visual (n=34).
and tonic (n=65) responses. The saccadic responses were a decrease (n=40) and an increase (n=24) in discharge rate; their onsets preceded (n=20)
or followed
showed omnidirectional
responses. A half of saccadic cells also showed reward-related activity (n=33) and/or eye fixation-
(n=44)
the saccadic onsets. Movement
field was usually over a hemifield;
32 cells
related tonic activity (n=35). The non-selective nature of GPe neurons suggests that the indirect pathway provides the output areas with surrounding facilitatory or inhibitory effects which would contrast with specific motor signals conveyed by the direct pathway.
[GPilGPe: internal/external
14-30
segment of globus pallidus; SNr: pars reticulata of substantia nigra]
DISTURBANCE OF VOLUNTARY CONTROL OF SACCADIC EYE MOVEMENT IN PATIENTS WITH FRONTAL CORTICAL LESIONS AND PARKINSON'S DISEASE. JUNK0 FUKUSHIMA, KIKURO FUKUSHIMA, MAYUMI KITAGAWA, NOBUYUKI MORITA TATSUO HATTA, ITARU YAMASHITA, College --of Med Tech, Depts of Physiol, Neural, andiatr, Sch of Med, Hokkaido Univ, Sapporo 060, Japan. -T-We reported that many schizophrenic patients showed more errors and longer latencies than controls in the antisaccade task, despite their normal results in the simple saccade task: and that these abnormalities were correlated with frontral cortical atrophy in CT scans (J Fukushima et al 1988,1990,1991). The frontal eye field, prefrontal cortex and dorsomedial frontal cortex are To examine whether these abnormalities can be explained by known to control saccadic eye movement. in this study 10 patients with frontal cortical dysfunction of the frontal cortex, we examined lesions using the same tasks. Four patients with lesions covering the frontal eye field and prefrontal cortex showed more errors and longer latencies than age-matched controls in the antisaccade task, despite their normal results in the simple saccade task. The error rates of 6 patients with medial frontal cortical lesions were within the normal range, although they showed longer latencies in the antisaccade task. As a further comparison, we also examined 32 patients with Parkinson's disease. Severe cases (Yahr III) showed more errors than controls in the antisaccade task, although mild cases (Yahr I-II) did not show a significant difference. Latencies of saccades increased significantly in severe cases in the simple saccade task as well as in the antisacade task. These results suggest that the abnormalities of many schizophrenics in the antisaccade task are similar to those of patients with lesions of the frontal eye field and prefrontal cortex.
14-28
EFFECT OF SUPERIOR COLLICULAR LESION ON ELECTRICALLY-ELICITED SACCADES OF THE FRONTAL EYE FIELD IN MONKEY. MASAO AZUMA, YASUSHI KODAKA AND HISAO SUZUKI, Department of Physiology, Hirosaki University School of Medicine, Hirosaki 036, Japan We studied the effect of lesions of the superior colliculus (SC) on the saccades elicited by focal intracortical microstimulation (ICMS) of the frontal eye field (FEF) in an alert monkey with the head immobilized. ICMSs evoked saccades directing toward the contralateral side with a latency period of 27-65 ms and with the threshold of more than 8pA. The latency was short when the threshold was low. As described previously, the amplitude of the saccades was small at the stimulating sites in the lateral part of the FEF, while it was large in the medial FEF. After the ipsilateral SC lesion by injections of kinic acid, we failed to find any systematic change in the topographic organization of the saccade amplitude. However, both the latency and threshold increased and were 44-77 ms and more than The increase of the latency was resulted not only from the 13 PA, respectively. loss of the low threshold but also from an increase of about 10 ms at each These findings may suggest a role of the SC to facilitate generation of threshold. the cortically induced saccades.
14-29
SACCADE-RELATED MAKOTO
KATO
RESPONSES
and OKIHIDE
OF EXTERNAL
HIKOSAKA.
PALLIDAL
NEURONS IN MONKEY.
National Institute for Phvsioloeical Sciences. Mvodaiii. Okazaki
444, Japan. The basal ganglia contain two types of pathways connecting the input areas (caudate/putamen) (GPi/SNr);
with the output areas
one directly, and the other indirectly (via GPe and/or subthalamic nucleus). The direct pathway (e.g.,caudate-
SNr) acts to disinhibit the target structures (e.g., superior colliculus) to facilitate initiation of movements (e.g.. saccadic eye movement). But the function of the indirect pathway is unclear. We then recorded single cell activities from the GPe in the monkey performing visuo-oculomotor
tasks. Out of 400 GPe neurons recorded were found saccadic (n=64),
visual (n=34).
and tonic (n=65) responses. The saccadic responses were a decrease (n=40) and an increase (n=24) in discharge rate; their onsets preceded (n=20)
or followed
showed omnidirectional
responses. A half of saccadic cells also showed reward-related activity (n=33) and/or eye fixation-
(n=44)
the saccadic onsets. Movement
field was usually over a hemifield;
32 cells
related tonic activity (n=35). The non-selective nature of GPe neurons suggests that the indirect pathway provides the output areas with surrounding facilitatory or inhibitory effects which would contrast with specific motor signals conveyed by the direct pathway.
[GPilGPe: internal/external
14-30
segment of globus pallidus; SNr: pars reticulata of substantia nigra]
DISTURBANCE OF VOLUNTARY CONTROL OF SACCADIC EYE MOVEMENT IN PATIENTS WITH FRONTAL CORTICAL LESIONS AND PARKINSON'S DISEASE. JUNK0 FUKUSHIMA, KIKURO FUKUSHIMA, MAYUMI KITAGAWA, NOBUYUKI MORITA TATSUO HATTA, ITARU YAMASHITA, College --of Med Tech, Depts of Physiol, Neural, andiatr, Sch of Med, Hokkaido Univ, Sapporo 060, Japan. -T-We reported that many schizophrenic patients showed more errors and longer latencies than controls in the antisaccade task, despite their normal results in the simple saccade task: and that these abnormalities were correlated with frontral cortical atrophy in CT scans (J Fukushima et al 1988,1990,1991). The frontal eye field, prefrontal cortex and dorsomedial frontal cortex are To examine whether these abnormalities can be explained by known to control saccadic eye movement. in this study 10 patients with frontal cortical dysfunction of the frontal cortex, we examined lesions using the same tasks. Four patients with lesions covering the frontal eye field and prefrontal cortex showed more errors and longer latencies than age-matched controls in the antisaccade task, despite their normal results in the simple saccade task. The error rates of 6 patients with medial frontal cortical lesions were within the normal range, although they showed longer latencies in the antisaccade task. As a further comparison, we also examined 32 patients with Parkinson's disease. Severe cases (Yahr III) showed more errors than controls in the antisaccade task, although mild cases (Yahr I-II) did not show a significant difference. Latencies of saccades increased significantly in severe cases in the simple saccade task as well as in the antisacade task. These results suggest that the abnormalities of many schizophrenics in the antisaccade task are similar to those of patients with lesions of the frontal eye field and prefrontal cortex.