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The afferent and efferent connections of the vibrissal area of the rat motor cortex (VMCx) were investigated by injecting Phaseolus vulgaris leucoagglutinin (PHA-L) or wheat germ agglutinin-horseradish peroxidase into the physiologically defined VMCx. The VMCx formed reciprocal connections with the primary and secondary somatosensory cortex, lateral and(More)
The branching pattern of individual pyramidal tract (PT) neurons of the monkey motor cortex was studied by activating these neurons antidromically from within the cervical motor nuclei and also from other regions of the spinal cord. 1. Fifty-four neurons were activated from motor nuclei in the cervical cord. Twenty-eight of these were activated from one(More)
The effective spread of stimulating current for pyramidal tract (PT) cells and fibers was studied using a method of cancelling the shock artifacts and the following results were obtained: 1. The excitability of PT axon collaterals was as high as that of PT cells. 2. These axon collaterals extended as far as 1.0 mm horizontally from the PT cells. 3. The low(More)
1. The projection from the somatosensory cortex to the primary motor cortex has been proposed to play an important role in learning novel motor skills. This hypothesis was examined by studying the effects of lesions to the sensory cortex on learning of new motor skills. 2. We used two experimental paradigms to reveal the effects of lesions on learning of(More)
1. Intracellular recordings were obtained from neurons in the motor cortex (MCx), in which excitatory postsynaptic potentials (EPSPs) were evoked by microstimulation of the somatosensory cortex (SCx) and the ventrolateral nucleus (VL) of the thalamus. The effects of combined tetanic stimulation of SCx and VL on the amplitudes of these EPSPs were studied. 2.(More)
We have shown (Asanuma et al., 1979c) that the monkey motor cortex receives peripheral somesthetic inputs directly from the thalamus. In the present experiments, we studied the pathways which mediated these inputs by stimulating superficial radial (SR) and deep radial (DR) nerves and recording evoked potentials from the motor and sensory cortices and the(More)