The ultimate purpose of the proposed study is to increase our understanding of how the motor cortex controls movement and subsequently to contribute toward the better treatment of human motor dysfunctions.
The specific aims during the coming years are to explore the neuronal mechanisms underlying the motor learning in higher mammals. During the past grant period, we have discovered that tetanic stimulation of the sensory cortex produces long term potentiation (LTP) of synaptic potentials in the motor cortex in cats raising the possibility that this cortico-cortical (CC) input participates in motor learning and memory. During the coming years, following experiments will be carried out. The purpose of these experiments are to-examine 1) whether all CC input to and from the motor cortex produces LTP by delivering tetanic intracortical microstimulations to the motor cortex or other cortices projecting to the motor cortex, 2) whether this input actually participates in motor learning by training the monkey for a new motor skill with and without the projection area to the motor cortex. Then we will examine 3) whether all CC input in the cerebral cortex can produce LTP and 4) whether the pyramidal tract also produces LTP. Besides, we will examine 5) whether LTP is the only plastic change resulting from repeated activity of the sensory cortex. The last experiment will be done by delivering repetitive burst stimulations to the sensory cortex chronically and then counting the number of synapses at the terminal branches of CC fibers in the motor cortex. The results will hopefully open a new field for the study of motor learning and memory in higher mammals including the primate.
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|Kaneko, T; Caria, M A; Asanuma, H (1994) Information processing within the motor cortex. II. Intracortical connections between neurons receiving somatosensory cortical input and motor output neurons of the cortex. J Comp Neurol 345:172-84|
|Kaneko, T; Caria, M A; Asanuma, H (1994) Information processing within the motor cortex. I. Responses of morphologically identified motor cortical cells to stimulation of the somatosensory cortex. J Comp Neurol 345:161-71|
|Miyashita, E; Keller, A; Asanuma, H (1994) Input-output organization of the rat vibrissal motor cortex. Exp Brain Res 99:223-32|
|Pavlides, C; Miyashita, E; Asanuma, H (1993) Projection from the sensory to the motor cortex is important in learning motor skills in the monkey. J Neurophysiol 70:733-41|
|Keller, A; Asanuma, H (1993) Synaptic relationships involving local axon collaterals of pyramidal neurons in the cat motor cortex. J Comp Neurol 336:229-42|
|Keller, A; Arissian, K; Asanuma, H (1992) Synaptic proliferation in the motor cortex of adult cats after long-term thalamic stimulation. J Neurophysiol 68:295-308|
|Asanuma, H; Keller, A (1991) Neuronal mechanisms of motor learning in mammals. Neuroreport 2:217-24|
|Keller, A; Miyashita, E; Asanuma, H (1991) Minimal stimulus parameters and the effects of hyperpolarization on the induction of long-term potentiation in the cat motor cortex. Exp Brain Res 87:295-302|
|Iriki, A; Pavlides, C; Keller, A et al. (1991) Long-term potentiation of thalamic input to the motor cortex induced by coactivation of thalamocortical and corticocortical afferents. J Neurophysiol 65:1435-41|
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