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Electrophysiology and morphology of respiratory neurons in brainstem-spinal cord preparations from newborn rats
s221
14-37
MUSCIMOL INJECTIONS INTO THE PREMOTOR CORTEX INDUCED DIRECTIONAL ERRORS IN MEMORY-GUIDED REACHING MOVEMENTS. VYAMANE: TOSHTYTJKT SAW‘.’ 0 ITtllVe.rsltv.
We examined reaching movement deficits by local injections of muscimol (GABAa agonist, 30 pg dissolved in ! ~1 saline) into the premotor cortex (PM) of two rhesus monkeys who performed a delayed response task. The task was initiated by pressing a central hold lever, and one of three target cues (left, upper and right) appeared (for 500 ms). After 2 or 5 s delay period, a go signal appeared, and then the monkeys released the lever and reached to one of three target levers above which the cue had been presented. In a control task, the cue remained on the delay period and the monkeys did visually guided reaching movements. In the ventral PM (postarcuate area), the injections (22 sites) increased reaction time (from the go signal to the lever release) in both the delayed response and control tasks. In the dorsal PM (caudodorsal area), the injections (12 sites) caused directional errors (pressing a wrong target lever) in the delayed response. The directional errors were sensitive to the duration of the delay period, and more errors occurred in longer delay period. Errors rarely occurred in the control task. These deficits are considered to be due to the suppression of neural activity around the injection site where GABAa inhibition was enhanced extremely. The present data suggest that the ventral PM participates in the movement onset, and that the dorsal PM may be involved in not only motor control but also sclme cognitive function such as spatial short-term memory.
14-38
ELECTROPHYSIOLOGY AND MORPHOLOGY OF RESPIRATORYNEURONSIN BRAINSTEM-SPINAL CORD HIROSHI ONIMARUand IKUO HOMMA, PREPARATIONSFROM NEWBORN RATS. AKIKO Am
Dept. of Physiology,
Univ. _Showa ---
School of Med.,
Hatanodai
MxaKku,
Tokyo
142 Japan
Previous study of brainstem-spinal cord preparations from newborn rats suggested that pre-inspiratory (Pre-I) neurons, which exist in the rostra1 ventrolateralmedulla, generate respiratory rhythm and trigger inspiratory (I) neurons. Recent development in whole-cell recording allows routine analysis of the morphology of recorded neurons that are labeled by and fluorescent dye. The purpose of the present study was to investigate electrophysiological morphological characteristics of Pre-I and I neurons by whole-cell recording. Patch pipette 1% Lucifer solutions contained: 130 K-gluconate, 10 EGTA, 10 HEPES, 1 CaC12, 1 MgC12, and Yellow (LY) (or 1% LY plus 100 pg/ml Nystatin, as described in the Abstract of Onimaru et al.). Recorded neurons were electrophysiologically characterized by membrane resistance, bursting pattern and post synaptic potentials. The axonal projections of the neurons were examined by stimulating IX/X cranial nerves and descending fibers at the C3 level. The tissue was cut into serial transverse 70 pm sections and the labeled neurons were reconstructed with the aid of a camera lucida attached to the microscope. Morphological characteristics included soma size, soIla shape, dendritic field and distribution of the axons. Axons of some Pre-I neurons ran toward t're NTS, and axons of some I neurons ran medially towards the contralateral ventral medulla, into tb'e cranial nerve root, or toward the NTS. Dendrites were observed in ventromedial-dorsolateral or dorsoventral orientation, and some projected close to the ventral surface.
14-39
SYNAPTIC ACTIVITIES OF TAIL MUSCLE MOTONEURONS BY STIMULATION OF HINDLIMB MUSCLE AFFERENT NERVES IN THE CAT. NAOMI WADA AND MIKIHIKO TOKURIKI, Department of Veterinary Physiology, Faculty of Agriculture, Yamaguchi University, Yamaguchi City, Yamaguchi 753, Japan Experiments were performed in 25 adult cats which were performed decerebration and spinalization at Ll spinal segments. Motoneuronal activities induced by electrical stimulation of muscle nerves(PBSt and GS) were recorded from 75 tail muscle (extensor caudae lateral) motoneurons. Synaptic activities by muscle nerve stimulation at 1.21.5T(stimulus intensity) were found in 3 motoneurons. EPSPs by stimulation of PBSt and GS muscle at 2-5T nerve were observed in 55 and 21 motoneurons, respectively. IPSPs by PBST and GS muscle nerve stimulation were observed in 3 and 11 motoneurons, respectively. Latency measurements suggest that the minimal linkage is disynaptic in the excitatory interneuronal pathways and trisynaptic in the inhibitory pathways. In some motoneurons, group II EPSPs occurred in combination with IPSPs.
14-37
MUSCIMOL INJECTIONS INTO THE PREMOTOR CORTEX INDUCED DIRECTIONAL ERRORS IN MEMORY-GUIDED REACHING MOVEMENTS. VYAMANE: TOSHTYTJKT SAW‘.’ 0 ITtllVe.rsltv.
We examined reaching movement deficits by local injections of muscimol (GABAa agonist, 30 pg dissolved in ! ~1 saline) into the premotor cortex (PM) of two rhesus monkeys who performed a delayed response task. The task was initiated by pressing a central hold lever, and one of three target cues (left, upper and right) appeared (for 500 ms). After 2 or 5 s delay period, a go signal appeared, and then the monkeys released the lever and reached to one of three target levers above which the cue had been presented. In a control task, the cue remained on the delay period and the monkeys did visually guided reaching movements. In the ventral PM (postarcuate area), the injections (22 sites) increased reaction time (from the go signal to the lever release) in both the delayed response and control tasks. In the dorsal PM (caudodorsal area), the injections (12 sites) caused directional errors (pressing a wrong target lever) in the delayed response. The directional errors were sensitive to the duration of the delay period, and more errors occurred in longer delay period. Errors rarely occurred in the control task. These deficits are considered to be due to the suppression of neural activity around the injection site where GABAa inhibition was enhanced extremely. The present data suggest that the ventral PM participates in the movement onset, and that the dorsal PM may be involved in not only motor control but also sclme cognitive function such as spatial short-term memory.
14-38
ELECTROPHYSIOLOGY AND MORPHOLOGY OF RESPIRATORYNEURONSIN BRAINSTEM-SPINAL CORD HIROSHI ONIMARUand IKUO HOMMA, PREPARATIONSFROM NEWBORN RATS. AKIKO Am
Dept. of Physiology,
Univ. _Showa ---
School of Med.,
Hatanodai
MxaKku,
Tokyo
142 Japan
Previous study of brainstem-spinal cord preparations from newborn rats suggested that pre-inspiratory (Pre-I) neurons, which exist in the rostra1 ventrolateralmedulla, generate respiratory rhythm and trigger inspiratory (I) neurons. Recent development in whole-cell recording allows routine analysis of the morphology of recorded neurons that are labeled by and fluorescent dye. The purpose of the present study was to investigate electrophysiological morphological characteristics of Pre-I and I neurons by whole-cell recording. Patch pipette 1% Lucifer solutions contained: 130 K-gluconate, 10 EGTA, 10 HEPES, 1 CaC12, 1 MgC12, and Yellow (LY) (or 1% LY plus 100 pg/ml Nystatin, as described in the Abstract of Onimaru et al.). Recorded neurons were electrophysiologically characterized by membrane resistance, bursting pattern and post synaptic potentials. The axonal projections of the neurons were examined by stimulating IX/X cranial nerves and descending fibers at the C3 level. The tissue was cut into serial transverse 70 pm sections and the labeled neurons were reconstructed with the aid of a camera lucida attached to the microscope. Morphological characteristics included soma size, soIla shape, dendritic field and distribution of the axons. Axons of some Pre-I neurons ran toward t're NTS, and axons of some I neurons ran medially towards the contralateral ventral medulla, into tb'e cranial nerve root, or toward the NTS. Dendrites were observed in ventromedial-dorsolateral or dorsoventral orientation, and some projected close to the ventral surface.
14-39
SYNAPTIC ACTIVITIES OF TAIL MUSCLE MOTONEURONS BY STIMULATION OF HINDLIMB MUSCLE AFFERENT NERVES IN THE CAT. NAOMI WADA AND MIKIHIKO TOKURIKI, Department of Veterinary Physiology, Faculty of Agriculture, Yamaguchi University, Yamaguchi City, Yamaguchi 753, Japan Experiments were performed in 25 adult cats which were performed decerebration and spinalization at Ll spinal segments. Motoneuronal activities induced by electrical stimulation of muscle nerves(PBSt and GS) were recorded from 75 tail muscle (extensor caudae lateral) motoneurons. Synaptic activities by muscle nerve stimulation at 1.21.5T(stimulus intensity) were found in 3 motoneurons. EPSPs by stimulation of PBSt and GS muscle at 2-5T nerve were observed in 55 and 21 motoneurons, respectively. IPSPs by PBST and GS muscle nerve stimulation were observed in 3 and 11 motoneurons, respectively. Latency measurements suggest that the minimal linkage is disynaptic in the excitatory interneuronal pathways and trisynaptic in the inhibitory pathways. In some motoneurons, group II EPSPs occurred in combination with IPSPs.