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Activation of D1 dopamine receptor in the premotor cortex facilitates the neuronal activity for reaching movement
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FUNCTIONAL DIFFERENTIATION OF GABAERGIC NON-PYRAMIDAL CELLS IN RAT FRONTAI. CORTEX IN VITRO. YASUO KAWAGUCHI AND YOSHIYUKI KUBOTA, Laboratorv for Neural Svstems, Frontier Research Program. RIKEN, 2-l Hirosawa, Wako-shi, Saitama 35 I-01. Jaoan Physiological and morphological properties of layer V non-pyramidal were studied in slices of frontal cortex from young rats by whole cell, current-clamp recording, coupled with intracellular staining by biocytin. Two physiological categories of non-pyramidal cells were identified: fast-spiking (FS) cells and low-threshold spike (LTS) cells. FS cells had lower input resistance and shorter spike-width than LTS cells. Low threshold spikes induced by depolarizing current pulses were observed at hyperpolarized potentials in LTS cells, but not in FS cells. Spike trains elicited by depolarizing pulses in FS cells showed almost no spike-frequency adaptation, while those in LTS cells showed adaptation. A combination of stimulation-induced EPSPs with depolarization caused repetitive firing in FS cells which was abolished by NMDA receptor blockers. Repetitive firing was not observed in LTS cells under these conditions. Axons of FS cells distributed more densely near the somata and long branches ran horizontally giving off basket terminals, whereas LTS cells extended axons more vertically up to layer I. Combination of intracellular staining with subsequent double immunostaining for calcium-binding proteins (CBPs) showed that FS cells were parvalbumin-immunoreactive, while LTS cells were calbindin D28k-immunoreactive. Most cells immunoreactive for the CBPs in layer V were also immunoreactive for GABA. These results suggest that GABAergic non-pyramidal cells in layer V of neocortex can be divided into two functional groups on the basis of different tiring modes, axonal distributions and CBP immunoreactivity.
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CORTEX IN CONTROLS OF PRIMATE MOTOR ROLE OF GABAB INHIBITION OF THE KISOU KUBOTA, REACHING MOVEMENT IN FREELY MOVING, INFANT MACAQUE MONKEYS. Kyoto University, Inuyama, Aichi 484, Japan. Department of Neurophysiolosy, cortex in the To understand roles of GABAB inhibition of the monkey motor GABAb agonist (Baclofen, 2-5 )Ig) and its antagonist (Phacloreaching movement, cortex of infant macaques (4 g) were injected locally into the motor fen, l-5 (n=40>) were made in macaca mu r atas and 1 macaca fuscata; 6-14 m old). Injections (N20+02 anesthetized state [5-18 mg ketamine, i.m. or ketamine and gas anesthesia from which convulsions of forearm and upper arm were and 1% halothane) 1 to sites injections (presumably, the forearm motor bicuculline induced by intracortical hand to the apple-piece, and to movement by the contralateral area). Reaching it to the mouth or reaching movement to the inverted, small bring, by grasping, to bottle cap and to expose, grasping and raising it, the hidden apple-piece for 30-60 min during the recovered state from bring it to the mouth were observed The time from the GO signal to the movement onset was not influthe anesthesia. or apple-piece by pinching was proenced but the time to hold the bottle cap Monkeys tended to use the ipsilateral hand. longed by both agonist and antagonist. This is due to disruptions of the GABAB inhibition. It is suggested that, differimportant to produce directionality of the movement ent from GABAA inhibition, movement pattern. pattern, GABAB inhibition is important to sustain directional
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ACTIVATIONOF Dl DOPAMINE RECEPTOR IN THE PREMOTOR CORTEX FACILITATES THE NEURONAL, ACTIVITY FOR REACHING MOVEMENT. TastrrYIKt
-1
YAMANF. AND KtSrur Kr
The premotor cortex (PMC) of monkeys contains a high level of Dl dopamine receptors (Berger et al., 1991), and we have recently demonstrated that local injections of a Dl antagonist, SCH23390, into the PMC induce deficits in reaching movement (Sawaguchi et al., 1992). To examine further the roles of PMC dopamine receptors for visual reaching movement, we investigated the effects of iontophoretically applied dopamine antagonists (0.2 M sulpiride, a D2 antagonist, and 0.2 M SCH23390) on the PMC neuronal activity while two rhesus monkeys performed a cognitive visual reaching task. The task was initiated by pressing a central hold lever, followed by 1s of a waiting period, and one of three target cues (left, upper and right) appeared for 0.5 s. After 4 s of a delay period, a go signal appeared, and then the monkeys released the lever to reach to one of three target levers above which the cue had been presented (go period). Fifty five PMC neurons showed changes in activity during the delay period and/or the go period of the task. Iontophoretically applied SCH23390 (usually with a 50 nA of current) decreased the activity of most of these neurons (n=50/55), and the application with a larger current (90 or 100 nA) decreased the activity more strongly. Further, SCH23390 affected more strongly the task-related activity compared to background activity during the waiting period, and, hence, the taskrelated activity became less clear during the application. By contrast, the application of sulpiride did not affect the task-related or background activity for all of neurons tested (n=39). These findings suggest that the activation of Dl receptors in the PMC facilitates the neuronal activity that is related to goal-directed reaching movement.
14-34
FUNCTIONAL DIFFERENTIATION OF GABAERGIC NON-PYRAMIDAL CELLS IN RAT FRONTAI. CORTEX IN VITRO. YASUO KAWAGUCHI AND YOSHIYUKI KUBOTA, Laboratorv for Neural Svstems, Frontier Research Program. RIKEN, 2-l Hirosawa, Wako-shi, Saitama 35 I-01. Jaoan Physiological and morphological properties of layer V non-pyramidal were studied in slices of frontal cortex from young rats by whole cell, current-clamp recording, coupled with intracellular staining by biocytin. Two physiological categories of non-pyramidal cells were identified: fast-spiking (FS) cells and low-threshold spike (LTS) cells. FS cells had lower input resistance and shorter spike-width than LTS cells. Low threshold spikes induced by depolarizing current pulses were observed at hyperpolarized potentials in LTS cells, but not in FS cells. Spike trains elicited by depolarizing pulses in FS cells showed almost no spike-frequency adaptation, while those in LTS cells showed adaptation. A combination of stimulation-induced EPSPs with depolarization caused repetitive firing in FS cells which was abolished by NMDA receptor blockers. Repetitive firing was not observed in LTS cells under these conditions. Axons of FS cells distributed more densely near the somata and long branches ran horizontally giving off basket terminals, whereas LTS cells extended axons more vertically up to layer I. Combination of intracellular staining with subsequent double immunostaining for calcium-binding proteins (CBPs) showed that FS cells were parvalbumin-immunoreactive, while LTS cells were calbindin D28k-immunoreactive. Most cells immunoreactive for the CBPs in layer V were also immunoreactive for GABA. These results suggest that GABAergic non-pyramidal cells in layer V of neocortex can be divided into two functional groups on the basis of different tiring modes, axonal distributions and CBP immunoreactivity.
14-35
CORTEX IN CONTROLS OF PRIMATE MOTOR ROLE OF GABAB INHIBITION OF THE KISOU KUBOTA, REACHING MOVEMENT IN FREELY MOVING, INFANT MACAQUE MONKEYS. Kyoto University, Inuyama, Aichi 484, Japan. Department of Neurophysiolosy, cortex in the To understand roles of GABAB inhibition of the monkey motor GABAb agonist (Baclofen, 2-5 )Ig) and its antagonist (Phacloreaching movement, cortex of infant macaques (4 g) were injected locally into the motor fen, l-5 (n=40>) were made in macaca mu r atas and 1 macaca fuscata; 6-14 m old). Injections (N20+02 anesthetized state [5-18 mg ketamine, i.m. or ketamine and gas anesthesia from which convulsions of forearm and upper arm were and 1% halothane) 1 to sites injections (presumably, the forearm motor bicuculline induced by intracortical hand to the apple-piece, and to movement by the contralateral area). Reaching it to the mouth or reaching movement to the inverted, small bring, by grasping, to bottle cap and to expose, grasping and raising it, the hidden apple-piece for 30-60 min during the recovered state from bring it to the mouth were observed The time from the GO signal to the movement onset was not influthe anesthesia. or apple-piece by pinching was proenced but the time to hold the bottle cap Monkeys tended to use the ipsilateral hand. longed by both agonist and antagonist. This is due to disruptions of the GABAB inhibition. It is suggested that, differimportant to produce directionality of the movement ent from GABAA inhibition, movement pattern. pattern, GABAB inhibition is important to sustain directional
14-36
ACTIVATIONOF Dl DOPAMINE RECEPTOR IN THE PREMOTOR CORTEX FACILITATES THE NEURONAL, ACTIVITY FOR REACHING MOVEMENT. TastrrYIKt
-1
YAMANF. AND KtSrur Kr
The premotor cortex (PMC) of monkeys contains a high level of Dl dopamine receptors (Berger et al., 1991), and we have recently demonstrated that local injections of a Dl antagonist, SCH23390, into the PMC induce deficits in reaching movement (Sawaguchi et al., 1992). To examine further the roles of PMC dopamine receptors for visual reaching movement, we investigated the effects of iontophoretically applied dopamine antagonists (0.2 M sulpiride, a D2 antagonist, and 0.2 M SCH23390) on the PMC neuronal activity while two rhesus monkeys performed a cognitive visual reaching task. The task was initiated by pressing a central hold lever, followed by 1s of a waiting period, and one of three target cues (left, upper and right) appeared for 0.5 s. After 4 s of a delay period, a go signal appeared, and then the monkeys released the lever to reach to one of three target levers above which the cue had been presented (go period). Fifty five PMC neurons showed changes in activity during the delay period and/or the go period of the task. Iontophoretically applied SCH23390 (usually with a 50 nA of current) decreased the activity of most of these neurons (n=50/55), and the application with a larger current (90 or 100 nA) decreased the activity more strongly. Further, SCH23390 affected more strongly the task-related activity compared to background activity during the waiting period, and, hence, the taskrelated activity became less clear during the application. By contrast, the application of sulpiride did not affect the task-related or background activity for all of neurons tested (n=39). These findings suggest that the activation of Dl receptors in the PMC facilitates the neuronal activity that is related to goal-directed reaching movement.