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H Yumiya

Publications and source records attributed to H Yumiya.

16 recordsLinked to original sources
PubMed1984

Specialized subregions in the cat motor cortex: anatomical demonstration of differential projections to rostral and caudal sectors.

Ipsilateral cortico-cortical and thalamo-cortical projections to the cat motor cortex were determined from the locations of retrogradely labeled neurons following single small intracortical injections of HRP in area 4 gamma. These projections were also examined by studying the distribution of anterogradely transported axonal label following multiple injections of HRP or of tritiated amino acids in areas 1-2 of SI and in area 2pri (SII). The number of retrogradely labeled cells in areas 1-2 and in area 2pri differed markedly between HRP injection sites located in the precruciate (anterior sigmoid gyrus) and postcruciate (posterior sigmoid gyrus) subregions of area 4 gamma. These associational projections from primary and secondary somatosensory cortices were dense to postcruciate subregions but weak to the precruciate subregions. The associational projections from areas 1-2 and from area 2pri to the postcruciate subregion of area 4 gamma were topographically organized, but no clear topographic organization could be demonstrated for the precruciate projection. Anterograde terminal labeling following injection of either HRP or tritiated amino acids into areas 1-2 and area 2pri confirmed the preferential projection of somatosensory cortex to the postcruciate subregion of motor cortex. The projection from somatosensory areas 1-2 was uniform over its terminal field, but that from area 2pri was more patchy and complex. HRP injections in area 4 gamma gave rise to lamellae of labeled neurons in the ventrolateral nucleus of thalamus (VL). A topographic relationship was found between the site of injection and the location of the lamella of labeled neurons. The percentage of retrogradely labeled neurons in the shell zone surrounding the border of the ventrolateral nucleus and the ventrobasal complex (VB) was greater following postcruciate than precruciate injections, whereas fewer retrogradely labeled neurons were found in central lateral nucleus (CL) after postcruciate injections than after precruciate injections. These observations support the hypothesis that differential cortical and thalamic projections to different subregions of area 4 gamma may give rise to the different physiological properties of neurons observed in these subregions (Vicario et al. 1983; Martin et al. 1981).

Afferent Pathways↗
PubMed1982

Physiological properties of neurons projecting from area 3a to area 4 gamma of feline cerebral cortex.

1. The corticocortical projection from area 3a to area 4 gamma was restudied using tranquilized cats. 2. Intracortical microstimulation (ICMS) of a given locus in area 3a produced effects on neurons in area 4 gamma that were located in a small area extending along the direction of the radial fibers constituting a columnar shape. 3. Cortical neurons in area 3a that projected to a particular neuron in area 4 gamma were located in a region that extended along the direction of the radial fibers and constituted a columnar shape. 4. Two-thirds of the projection neurons in area 3a had different receptive fields from those of neurons in the projected area in 4 gamma, thus suggesting that the 3a neurons are not simply transferring peripheral information to the 4 gamma neurons. 5. ICMS delivered to area 3a rarely excited 4 gamma neurons but rather facilitated their evoked discharges. 6. It is suggested that the activity of corticocortical projection from area 3a to 4 gamma can influence the activity of 4 gamma neurons only when combined with other inputs to the motor cortex.

Animals↗
PubMed1980

The red nucleus of the monkey. Topographic localization of somatosensory input and motor output.

The topographic organization of somatosensory input to the primate red nucleus was investigated by studying receptive fields of rubral neurons, and that of the motor output by delivering trains of microstimulating pulses to evoke movements. A receptive field was identified in 191 of 208 rubral neurons. Most neurons (172) responded to passive movement of one or two joints including digits but some (26) had a cutaneous input. Neurons in both the parvocellular (RNpc) and magnocellular (RNmc) divisions of the nucleus had receptive fields. Neurons which responded to stimulation of the forelimb were located in the dorsomedial part of the nucleus. Those responsive to stimulation of the hindlimb were in the ventrolateral part. Thin regions on the dorsal and ventrolateral borders of the nuclei, respectively, contained neurons responsive to face and tail stimulation. Within the regions representing each limb, neurons receiving an input from the extremity (hand or foot) formed a core surrounded by neurons with an input from more proximal segments. This core extended uninterrupted throughout the RNpc and RNmc. Movements of individual limb segments including digits were readily evoked by microstimulating in the RNmc with thresholds as low as 3 microA. In most cases, movements were evoked in the direction opposite to the passive movement which drove the neurons at the stimulating site, although fibers of passage limited the analysis of the sensory input-motor output organization with stimulation. We conclude that there is topographic localization of somatosensory input and motor output in the macaque red nucleus. Furthermore, the red nucleus of monkeys contributes to the control of independent movements of limb segments including digits, although the number of axons it sends to the spinal cord is less than 1% of the number of corticospinal axons.

Animals↗
PubMed1980

Peripheral input pathways to the monkey motor cortex.

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 following results were obtained: 1. The focus for SR and DR evoked potentials in the sensory cortex was located in a circumscribed small area whereas in the motor cortex, the evoked potentials were distributed in a wide area along the central sulcus including the distal forelimb area. 2. Ablation of the sensory cortex reduced the size, but neither abolished nor changed the latency of the evoked potentials in the motor cortex. 3. Section of dorsal column nearly abolished the evoked potentials in the motor cortex, but only halved their size in the sensory cortex. 4. Section of ventrolateral cervical column including the spinothalamic tract halved the size of evoked potentials in the sensory cortex, but did not change the size in the motor cortex. 5. It is concluded that direct peripheral inputs to the motor cortex are mediated primarily through the dorsal column system whereas the peripheral inputs to the sensory cortex are mediated through both dorsal column and spinothalamic tract.

Animals↗
PubMed1979

Receptive fields of thalamic neurons projecting to the motor cortex in the cat.

The locations and receptive fields of thalamic neurons projecting to the motor cortex were examined and the following results were obtained. (1) Neurons located at the border area between nucleus ventralis lateralis (VL) and nucleus ventralis posterolateralis (VPL) could be activated antidromically from the motor cortex. (2) These neurons received topographically organized somesthetic inputs arising from skin and deep receptors. (3) The receptive fields of neurons in the small area of the motor cortex where these thalamic neurons projected could be examined in 8 instances. In 6 instances, the cortical neurons and the thalamic projection neurons were activated by exactly the same stimuli in the periphery. (4) Removal of the sensory cortex did not significantly change the characteristics of afferent inputs from the periphery to the motor cortex. (5) It is concluded that the motor cortex receives somesthetic inputs directly from the thalamus. The functional role of these inputs was discussed in relation to the known cortical reflexes.

Animals↗
PubMed1979

Organization of the convergence in the intermediate cerebellar nuclei of somatosensory receptive fields with motor cortical-evoked responses.

The convergence in the intermediate cerebellar nuclei of somatosensory inputs with those from the motor cortex was investigated in cats (1) by examining with natural stimulation the receptive field of nuclear neurons, and (2) by determining the response of the same neurons to stimulation of motor cortical sites which had been identified by microstimulation-evoked movements. Of 196 neurons studied, a response to natural stimulation could be identified in 143, more than half of which (83) were driven by passive movement of one or two joints. The predominant response to cortical microstimulation was a suppression of discharge, although the suppression was sometimes preceded by a weak facilitation or interrupted by a brief but strong facilitation. A pattern of convergence was identified in which 72% of those cells driven by passive joint movement in one direction were suppressed by stimulation of the cortical site from which movement could be evoked in the opposite direction. A model based on this convergence is proposed.

Afferent Pathways↗
PubMed1979

Stimulus and behavioral factors contributing to the activation of monkey prefrontal neurons during gazing.

Many neurons in the inferior dorsolateral area of the monkey prefrontal cortex showed sustained increases in discharge rates during continuous gazing at a tiny light spot that had a reward significance. These increases might depend upon stimulus factors (light target), behavioral factors (gazing) or both. In this report, we tried to separate these factors and to test the extent to which each factor might contribute to the neuronal reaction. Monkeys were trained to exhibit two kinds of behavior: 1) maintained gazing at a light target and 2) "gazing" behavior without a clear target. We then examined neuronal behavior in these two kinds of gazing behavior. During "gazing at target," many prefrontal neurons showed tonic activation; thus the previous findings were confirmed. These neurons behaved in various ways in "gazing without target": 1) some of the neurons were activated to the same extent as in "gazing at target"; 2) many others also showed activation but with lower discharge rates; and 3) the rest of the neurons completely ceased activation. Such variation in discharge patterns may be interpreted as meaning that there is a continous and graded difference among individual neurons in the dependence of their gaze-related activation upon a visible target. Then it seems that the stimulus factors are involved in a graded manner in generation of the activation, and further that other factors, probably behavioral ones, also contribute in part to it.

Action Potentials↗
PubMed1977

Neuronal activity in cortical efferent zones projecting to wrist extensors during voluntary wrist extension in the monkey.

Three monkeys were trained to make rapid wrist extension on presentation of a cue light. After training the animal sufficiently, unit activity was recorded from the cortical efferent zones corresponding to the wrist extensors. Most neurons in the wrist extensor zone were increased in their discharge rate during the wrist extension. Their activation pattern, especially the onset time, varied among different neurons. The earliest neuron was activated 65 msec before the EMG onset of the wrist extensors, while the latest did 30 msec after the EMG onset. About 80% of them activated before the EMG onset. In contrast, variation of the discharge onset of each neuron was rather small and 5-15 msec in quartile deviation. These findings may suggest that each neuron in the cortical efferent zone functions in different timing in the voluntary phasic contraction of the target muscle.

Animals↗