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10.18 Influences of bipedal walking on neuronal systems(using rat bipedal-walking model: RBM)
Chapter 10. Neurophysiology of motor control: animal models' latencies of automatic postural responses are delayed, and balance is impaired [1]. We introduce a new method for correlating temporal patterns of muscle activation with task-level variables in the context of postural responses to perturbation. Methods: We measured postural responses to support surface translations before and after loss of group I afferents induced by pyridoxine intoxication [1]. We reconstructed temporal EMG patterns using a feedback loop with delays, on CoM acceleration, velocity, and displacement. Results: Prior to lesion, temporal EMG patterns were well reconstructed using delayed feedback on CoM kinematics. After neuropathy, the delay in postural response latency was attributed to a loss of acceleration feedback. A compensatory increase in velocity feedback was also observed. Discussion: Feedback on CoM acceleration is necessary for normal postural latencies associated with balance control. The sensory information related to acceleration is encoded in group I sensory afferents. Conclusion: Dynamics of high-level task variables determine temporal EMG patterns for postural control. Loss of large diameter proprioceptive afferents disrupts acceleration feedback.
References [1] Stapley PJ, Ting LH, Hulliger M, Macpherson JM. J Neurosci 2002; 22:5803 5807.
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Influences of bipedal walking on neuronal systems (using rat bipedal-walking model: RBM)
N. Wada, E Mori, S. Hirano, W. Iwamoto, N. Kato, G. Suzuki, S. Mori. Department of Veterinary Physiology, Yamaguchi University,
Yamaguchi 753 8515, Japan After bilateral forelimb amputation, rats can be trained to perform stable upright posture and bipedal (BP) walking. This indicates that in the rat BP walking model (RBM), modifications occur in the skeletomuscle and neuronal systems which allow the transformation from quadrupedal (QP) to BP walking. In the present experiments, we evaluated electrophysiologically the effects of BP walking on spinal reflex pathways. Normal control and RBM rats were compared from 1 week to 6 months after BP training. Animals were anesthetized by intraperitoneal injection of Ketamine (100 200mg/kg). Cuff stimulating electrodes were mounted on the muscle nerves of m. quadriceps femoris (Q) on both sides. A laminectomy was performed between L2 and L6 and the distal end of the ventral root originating from L3-L5 spinal segments on both sides were cut for recording the reflex induced by electrical stimulation of Q. The incoming volley was also recorded by monopolar recording electrodes that were placed on the spinal cord. Mono- and polysynaptic reflexes were induced by electrical stimulation with single and double pulses (duration: 0.1 ms) at 1.2 5 T. The intervals between double electrical stimulations were changed from 0.5ms to 10ms. The effects of the double stimulation on mono- and polysynaptic reflexes varied according to the interval of double stimulation. Intervals which showed significant effects on mono and polysynaptic reflexes were prolonged in RBM. The results suggest that the modified spinal reflex pathway has a critical functional role in the elaboration of BP walking in RBM.
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Kinematic and electromyographic studies of the rat bipedal-walking model (RBM)
N. Wada 1, F. Mori 1, N. Kato 1, S. Hirano 1, W. Iwamoto 1, G. Suzuki 1, S. Mori 2. 1Department of Veterinary Physiology, Yamaguchi
University, Yamaguchi 753-8515, Japan," 2National Institute for Physiological Sciences', Japan
The purpose of our experiments using rat bipedal (BP) walking models (RBMs) is to investigate the influences of BP walking on neuronal systems. In this study, we attempted to analyze the BP acquisition process by way of kinematic analysis and electromyographic (EMG)
$63
recording. Wistar rats were used for the experiments. Within 30 hours of delivery, we amputated both forelimbs of pups under hypothermia anesthesia at 4 C °. The pups were weaned at 3 weeks and placed in a large cage with drip bottles placed 5 8 cm above floor level. At 4 6 weeks after birth, training in BP walking was initiated using a specially designed BP training system for 30 min, 6 d/wk. During BP walking the EMG from m. longissimus (Long) and m. quadriceps femoris (Q) on both sides were recorded and walking patterns were videotaped (250 fr/s) using a high-speed video camera. The videoframes and EMG bursts were synchronized using a 240 Hz signal, and both were stored in magnetic tape and magneto-optical disk, respectively. As training advanced, RBMs showed a more coordinated relationship among neighboring lower limb joints and became different from that seen during quadrupedal (QP) walking. Bilateral discharge patterns in Long were synchronized during QP walking, but an alternating discharge pattern was seen during BP walking. Together these results suggest that the physically-developing rat integrates new neural and musculoskeletal mechanisms required for the elaboration of BP walking.
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Locomotor discoordination in cerebellar Golgi cell-deficient mice
T. Watanabe, D. Yanagihara, W. Yue, R. Shigemoto, T. Yamamoto.
Aichi Shinshiro Otani University, Kawaji Aza Hagidaira 1 125, Shinshiro, Aichi 441 1306, Japan Introduction: The purpose of this study was to investigate cerebellar
Golgi cell function during the treadmill locomotion in mice, using the immunotoxin-mediated cell-specific targeting technique. Methods: Transgenic mice which expressed human inertleukin-2 receptor alpha subunit under the control of mGluR2 promotor were studied. Immunotoxin were injected into the subarachnoid space over the cerebellar vermis with a microinfusion pump, and this treatment induced the gait ataxia at 5 days after injection. Duration of step cycle and phase relationships between step cycles of the left and right forelimb and hindlimb were analyzed from the video data. Cycle period of EMG and duration of EMG burst were analyzed from the tibialis anterior (TA) and gastrocnemius (GM) EMG data. Results: The locomotion time on the treadmill were decreased at all speed with compared to Pre-test. In Post-test for the treadmill locomotion, coefficient of variations of these parameters were larger than that of Pre-test. Phase intervals between tow limbs were disturbed in Post-test compared with Pre-test. In TA, there were high background activity. Immunohistochemical analysis in there mice indicated that Golgi cells were ablated in the vermal part of the cerebellum. Discussion: Golgi cells receive excitatory inputs from mossy fibers and parallel fibers, and in turn send the inhibitory outputs to the granule cells. This inhibitory feed back circuit is thought to play a filtering function in the cerebellar information processing. Conclusion: Our study demonstrated that selective ablation of Golgi cells induced the gait disorder and abnormal EMG activities, specifically impairment of interlimb coordination.
References [1] Stapley PJ, Ting LH, Hulliger M, Macpherson JM. J Neurosci 2002; 22:5803 5807.
•
Influences of bipedal walking on neuronal systems (using rat bipedal-walking model: RBM)
N. Wada, E Mori, S. Hirano, W. Iwamoto, N. Kato, G. Suzuki, S. Mori. Department of Veterinary Physiology, Yamaguchi University,
Yamaguchi 753 8515, Japan After bilateral forelimb amputation, rats can be trained to perform stable upright posture and bipedal (BP) walking. This indicates that in the rat BP walking model (RBM), modifications occur in the skeletomuscle and neuronal systems which allow the transformation from quadrupedal (QP) to BP walking. In the present experiments, we evaluated electrophysiologically the effects of BP walking on spinal reflex pathways. Normal control and RBM rats were compared from 1 week to 6 months after BP training. Animals were anesthetized by intraperitoneal injection of Ketamine (100 200mg/kg). Cuff stimulating electrodes were mounted on the muscle nerves of m. quadriceps femoris (Q) on both sides. A laminectomy was performed between L2 and L6 and the distal end of the ventral root originating from L3-L5 spinal segments on both sides were cut for recording the reflex induced by electrical stimulation of Q. The incoming volley was also recorded by monopolar recording electrodes that were placed on the spinal cord. Mono- and polysynaptic reflexes were induced by electrical stimulation with single and double pulses (duration: 0.1 ms) at 1.2 5 T. The intervals between double electrical stimulations were changed from 0.5ms to 10ms. The effects of the double stimulation on mono- and polysynaptic reflexes varied according to the interval of double stimulation. Intervals which showed significant effects on mono and polysynaptic reflexes were prolonged in RBM. The results suggest that the modified spinal reflex pathway has a critical functional role in the elaboration of BP walking in RBM.
•
Kinematic and electromyographic studies of the rat bipedal-walking model (RBM)
N. Wada 1, F. Mori 1, N. Kato 1, S. Hirano 1, W. Iwamoto 1, G. Suzuki 1, S. Mori 2. 1Department of Veterinary Physiology, Yamaguchi
University, Yamaguchi 753-8515, Japan," 2National Institute for Physiological Sciences', Japan
The purpose of our experiments using rat bipedal (BP) walking models (RBMs) is to investigate the influences of BP walking on neuronal systems. In this study, we attempted to analyze the BP acquisition process by way of kinematic analysis and electromyographic (EMG)
$63
recording. Wistar rats were used for the experiments. Within 30 hours of delivery, we amputated both forelimbs of pups under hypothermia anesthesia at 4 C °. The pups were weaned at 3 weeks and placed in a large cage with drip bottles placed 5 8 cm above floor level. At 4 6 weeks after birth, training in BP walking was initiated using a specially designed BP training system for 30 min, 6 d/wk. During BP walking the EMG from m. longissimus (Long) and m. quadriceps femoris (Q) on both sides were recorded and walking patterns were videotaped (250 fr/s) using a high-speed video camera. The videoframes and EMG bursts were synchronized using a 240 Hz signal, and both were stored in magnetic tape and magneto-optical disk, respectively. As training advanced, RBMs showed a more coordinated relationship among neighboring lower limb joints and became different from that seen during quadrupedal (QP) walking. Bilateral discharge patterns in Long were synchronized during QP walking, but an alternating discharge pattern was seen during BP walking. Together these results suggest that the physically-developing rat integrates new neural and musculoskeletal mechanisms required for the elaboration of BP walking.
•
Locomotor discoordination in cerebellar Golgi cell-deficient mice
T. Watanabe, D. Yanagihara, W. Yue, R. Shigemoto, T. Yamamoto.
Aichi Shinshiro Otani University, Kawaji Aza Hagidaira 1 125, Shinshiro, Aichi 441 1306, Japan Introduction: The purpose of this study was to investigate cerebellar
Golgi cell function during the treadmill locomotion in mice, using the immunotoxin-mediated cell-specific targeting technique. Methods: Transgenic mice which expressed human inertleukin-2 receptor alpha subunit under the control of mGluR2 promotor were studied. Immunotoxin were injected into the subarachnoid space over the cerebellar vermis with a microinfusion pump, and this treatment induced the gait ataxia at 5 days after injection. Duration of step cycle and phase relationships between step cycles of the left and right forelimb and hindlimb were analyzed from the video data. Cycle period of EMG and duration of EMG burst were analyzed from the tibialis anterior (TA) and gastrocnemius (GM) EMG data. Results: The locomotion time on the treadmill were decreased at all speed with compared to Pre-test. In Post-test for the treadmill locomotion, coefficient of variations of these parameters were larger than that of Pre-test. Phase intervals between tow limbs were disturbed in Post-test compared with Pre-test. In TA, there were high background activity. Immunohistochemical analysis in there mice indicated that Golgi cells were ablated in the vermal part of the cerebellum. Discussion: Golgi cells receive excitatory inputs from mossy fibers and parallel fibers, and in turn send the inhibitory outputs to the granule cells. This inhibitory feed back circuit is thought to play a filtering function in the cerebellar information processing. Conclusion: Our study demonstrated that selective ablation of Golgi cells induced the gait disorder and abnormal EMG activities, specifically impairment of interlimb coordination.