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H Mushiake

Publications and source records attributed to H Mushiake.

At least 19 recordsLinked to original sources
PubMed1998

An oculomotor representation area within the ventral premotor cortex.

We explored the ventral part of the premotor cortex (PMV) with intracortical microstimulation (ICMS) while monkeys performed a visual fixation task, to see whether the PMV is involved in oculomotor control. ICMS evoked saccades from a small-restricted region in the PMV, without evoking movements in the limbs, neck, or body. We found the saccade-evoking site in the PMV in a total of three hemispheres in two monkeys. Quantitative analysis of the effects of eye position on saccades evoked by microstimulation of the PMV characterized the evoked saccades as goal directed. The nature of the saccades evoked in the PMV contrasted with the fixed vector nature of saccades evoked by ICMS of the frontal eye field. We also found that neurons in this restricted area of the PMV were active while the animals were performing a saccade task that required them to make saccades toward targets without arm movements. These data provide evidence for the presence of an oculomotor-specific subregion within the PMV. This subregion and the surrounding skeletomotor-representing regions of the PMV seem to coordinate oculomotor and skeletomotor control in performing goal-directed motor tasks.

Animals↗
PubMed1998

Intracortical microstimulation of bilateral frontal eye field.

We trained two monkeys to perform a fixation task. Intracortical microstimulation (ICMS) was applied to the monkey frontal eye field (FEF) while monkeys were fixating on one of five fixation LEDs. The ICMS was applied in two different manners. Under the single stimulation condition, ICMS was delivered to either right or left FEF. Under the paired stimulation condition, bilateral FEF were successively stimulated with an interval of 30-250 ms. The single stimulation elicited contraversive saccades. As reported previously, these saccades were not much affected by initial eye positions, maintaining the same vector. In contrast, the paired stimulation elicited double-step saccades. The first of the paired stimulation elicited constant vector saccades, but the second of the paired stimulation evoked saccades whose vector varied greatly depending on the eye position at the start of individual saccades. The second saccades, starting from various initial positions, were directed to the endpoint of saccades that were elicited from the same FEF site under the single stimulation condition. Endpoints of second saccades varied little despite variations of intervals of the stimulation pairs, ranging from 60 to 150 ms. On the basis of these observations, we propose a novel view that the FEF is involved in directing saccades to an internally referenced visual target.

Animals↗
PubMed1997

Neuronal activity in the ventral part of premotor cortex during target-reach movement is modulated by direction of gaze.

We recorded 200 neurons from the ventral part of the premotor cortex (PMv) and 110 neurons from the primary motor cortex (MI) of a monkey performing a visually cued arm-reaching task with a delay. We compared neuronal activity in the premovement period while the monkey reached the target with the eyes fixating on either a left or right fixation target. Our data demonstrate that about half of the movement-related activity in the PMv was modulated by the direction of gaze. In contrast, a vast majority of the activity of MI neurons and about half of PMv neurons were not influenced by the direction of gaze. We further analyzed the movement-related activity during the reaching movement to targets at the top, bottom, left, and right of each fixation point. The magnitude of activity of neurons showing the gaze-direction selectivity was primarily determined by the position of the reaching target relative to the eye-fixation target, and not by the position of the target relative to the animal's body. These data suggest that a part of the coordinate transformation of the motor command signals concerning the direction of reaching from the retinotopic to body-centered frame of reference may occur at the level of premotor cortex but not in MI.

Animals↗
PubMed1996

Role for cells in the presupplementary motor area in updating motor plans.

Two motor areas are known to exist in the medial frontal lobe of the cerebral cortex of primates, the supplementary motor area (SMA) and the presupplementary motor area (pre-SMA). We report here on an aspect of cellular activity that characterizes the pre-SMA. Monkeys were trained to perform three different movements sequentially in a temporal order. The correct order was planned on the basis of visual information before its execution. A group of pre-SMA cells (n = 64, 25%) were active during a process when monkeys were required to discard a current motor plan and develop a plan appropriate for the next orderly movements. Such activity was not common in the SMA and not found in the primary motor cortex. Our data suggest a role of pre-SMA cells in updating motor plans for subsequent temporally ordered movements.

Animals↗
PubMed1996

Comparison of neuronal activity in the supplementary motor area and primary motor cortex.

Neuronal activity in the supplementary motor area (SMA) and primary motor cortex (MI) have been compared in many experiments during performance of many different motor tasks. On one hand, the activity in both areas may appear similar, especially when the motor task is simple. On the other hand, if the motor tasks are more demanding, neuronal activity in the SMA exhibits a variety of complex relationship to many different aspects of motor behavior, while the activity in MI is mostly related to execution of motor task itself. Of particular interest is the neuronal activity in the SMA during preparation and execution of motor tasks when no external cues for the retrieval of appropriate motor act is available. Temporal sequencing of multiple movements is a typical example of the kind of motor task that requires profound activity in the SMA.

Animals↗
PubMed1996

Visually guided saccade versus eye-hand reach: contrasting neuronal activity in the cortical supplementary and frontal eye fields.

1. We studied neuronal activity in the supplementary eye field (SEF) and frontal eye field (FEF) of a monkey during performance of a conditional motor task that required capturing of a target either with a saccadic eye movement (the saccade-only condition) or with an eye-hand reach (the saccade-and-reach condition), according to visual instructions. 2. Among 106 SEF neurons that showed presaccadic activity, more than one-half of them (54%) were active preferentially under the saccade-only condition (n = 12) or under the saccade-and-reach condition (n = 45), while the remaining 49 neurons were equally active in both conditions. 3. By contrast, most (97%) of the 109 neurons in the FEF exhibited approximately equal activity in relation to saccades under the two conditions. 4. The present results suggest the possibility that SEF neurons, at least in part, are involved in signaling whether the motor task is oculomotor or combined eye-arm movements, whereas FEF neurons are mostly related to oculomotor control.

Animals↗
PubMed1995

Microstimulation of the supplementary eye field during saccade preparation.

Electrical stimulation of the supplementary eye field (SEF) of monkeys has been reported to evoke saccades with low threshold currents. In previous reports, the evoked saccades have appeared either as 'converging', 'goal directed', or at times 'constant vector'. In the present study, a new aspect of intracortical microstimulation (ICMS) was found when the stimulus was applied at the time when an animal was prepared to initiate its own voluntary saccades. A cue signal was given to the animal that indicated targets of impending saccades. After a variable delay period, a 'go' signal told the monkey to initiate the saccade toward the target. ICMS was applied shortly (50-100 ms) before the go signal. The stimulus-evoked saccades were directed toward and captured the cued target, provided that the target direction was contralateral to the cortical stimulus site. Saccades with that property were evoked only from a limited portion of the cortical field that corresponded to the SEF, characterizing this particular oculomotor area.

Animals↗
PubMed1995

Pallidal neuron activity during sequential arm movements.

1. We examined the activity of neurons in the globus pallidus (GP) while monkeys (n = 2) performed sequential pointing movements under two task conditions: visually guided (TRACK task) and remembered (REM task). 2. Almost two-thirds of the task-related neurons in GP (155/236) were considered task dependent because they displayed exclusive or enhanced (greater than +/- 50%) changes in activity for one of the two task conditions. 3. More than 65% of the task-dependent neurons were termed REM neurons because they either displayed changes in activity that occurred only during the REM task or displayed changes that were more pronounced (greater than +/- 50%) during the REM task than during the TRACK task. 4. Nearly half of the REM neurons in GP displayed changes in activity that were limited to a single phase of the REM task (i.e., phase specific). Phase-specific neurons varied in the extent to which their activity depended on the particular sequence of movements performed. Some displayed a change in activity for all of the eight different movement sequences. Others displayed a change in activity during only one of the eight different sequences (i.e., phase and sequence specific). 5. We speculate that an ensemble of GP neurons with phase-specific responses could be used to encode the detailed spatio-temporal characteristics of a sequential movement. In this way, GP neurons would provide part of the neural substrate that solves the "serial order of motor behavior problem".

Animals↗
PubMed1995

[Evaluation of new style of drug delivery system for primary lung cancer: intermittent intra-arterial injection therapy with subcutaneous infusible port I.--Temporary changes in feeding arteries of lung cancer in processes of intra-arterial injection therapy].

Arterial injection therapy for lung cancers is concentrated on the bronchial arteries, because they are reported by the main feeders of lung cancers. In the present study, we attempted intermittent arterial injection therapy with implantable port system. In the cases of lung cancers, in the present study, tumors were mainly fed by bronchial arteries originating from intercostal-bronchial arteries in right lungs, and those directly originating from aorta in the left lungs. However, in the processes of BAI (Bronchial Arterial Injection Therapy), main feeders often were obstructed and the new feeders originated from branches of subclavian arteries, such as thyro-cervical truncks, internal mammary arteries, thoraco-acromial arteries and intercostal arteries. They formed networks surrounding the lungs. Adequate study of the feeding arteries should be performed in the course of arterial injection therapy of lung cancers.

Adenocarcinoma↗
PubMed1995

[Evaluation of new drug delivery system for primary lung cancer: intermittent intra-arterial injection therapy with implantable port system (reservoir)--II. Evaluation of technical methods for cannulation of feeding arteries of lung cancer with implantation of implantable port system].

As mentioned in the first of the present series of reports, lung cancers were fed by various arteries such as bronchial arteries, internal mammary arteries, inter-costal arteries and branches of subclavian arteries such as thyro-cervical truncus or thoraco-dorsal arteries, according to the size and stages of tumors and the processes of therapy. On the basis of these anatomical findings of the feeders of lung cancers, we tried several effective and reasonable ways of cannulation of catheters, which were connected with an implantable port system.

Antineoplastic Agents↗
PubMed1993

Preferential activity of dentate neurons during limb movements guided by vision.

1. We recorded the activity of dentate neurons while monkeys (n = 2) performed sequential pointing movements under two task conditions: visually guided and remembered. For both conditions, a monkey faced a panel with five touch pads. The animal began a trial by placing his right hand on a hold key in front of him. In the Remembered Sequence Task, light-emitting diodes (LEDs) over three touch pads were illuminated in a sequence as an instruction to the monkey. At the end of a variable instruction period, an auditory "Go" signal told the monkey to release the hold key and press the touch pads according to the instructed sequence. In the Tracking Task, the monkey was required to press three touch pads immediately after the LED over each of them was illuminated. 2. We recorded from 172 neurons in the dentate that showed task-related changes in activity during the reaction time (RT) period (i.e., the interval between the onset of the Go signal and the release of the hold key). Approximately 40% of these neurons were considered task-dependent because they displayed exclusive or enhanced (> +/- 50%) changes in peak activity during the RT period for one of the two task conditions. Almost 80% of the task-dependent neurons displayed exclusive or enhanced activity changes during the Tracking Task. Many of these neurons were located ventral and lateral to dentate neurons, which were not task-dependent. 3. These results suggest that a portion of the dentate nucleus is preferentially involved in the generation and/or guidance of movement based on visual cues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Reorganization of activity in the supplementary motor area associated with motor learning and functional recovery.

The supplementary motor area (SMA) of primates has been implicated in the initiation and execution of limb movements. However, when a motor task was extensively overlearned, few SMA neurons, if any, were active before the movement onset. Subsequent lesions of the primary motor cortex gave rise to the appearance of premovement activity changes, indicating usedependent reorganization of the neuronal activity in SMA.

Animals↗
PubMed1991

Two movement-related foci in the primate cingulate cortex observed in signal-triggered and self-paced forelimb movements.

1. Single-unit activity in the cingulate cortex of the monkey was recorded during the performance of sensorially (visual, auditory, or tactile) triggered or self-paced forelimb key press movements. 2. Microelectrodes were inserted into the broad rostrocaudal expanse of the cingulate cortex, including the upper and lower banks of the cingulate sulcus and the hemispheric medial wall of the cingulate gyrus. 3. A total of 1,042 task-related neurons were examined, the majority of which were related to the execution of the key press movements. In greater than 60% of them, the movement-related activity preceded the activity in the distal flexor muscles. 4. The movement-related neurons were distributed, in two foci, in the posterior and anterior parts of the cingulate cortex, both including the upper and lower banks of the cingulate sulcus. The posterior focus was found to largely overlap the area projecting to the forelimb area of the primary motor cortex by the use of the horseradish peroxidase (HRP) method. 5. About 40% of the cingulate cortical neurons showed equimagnitude responses during the signal-triggered and self-paced movements. The neurons exhibiting a selective or differential response to the self-paced motor task were more frequently observed in the anterior than in the posterior cingulate cortex. 6. The long-lead type of changes in activity, ranging from 500 ms to 2 s, were observed mainly before the self-paced and, much less frequently, before the triggered movements. They were particularly abundant in the anterior cingulate cortex. 7. Only a few of the neurons showed activity time-locked to the onset of the sensory signals. 8. These observations indicate that the anterior and posterior parts of the cingulate cortex are distinct entities participating in the performance of limb movements, even if the movements are simple, such as those in this study.

Animals↗
PubMed1991

Neuronal activity in the primate premotor, supplementary, and precentral motor cortex during visually guided and internally determined sequential movements.

1. Single-cell activity was recorded from three different motor areas in the cerebral cortex: the primary motor cortex (MI), supplementary motor area (SMA), and premotor cortex (PM). 2. Three monkeys (Macaca fuscata) were trained to perform a sequential motor task in two different conditions. In one condition (visually triggered task, VT), they reached to and touched three pads placed in a front panel by following lights illuminated individually from behind the pads. In the other condition (internally guided task, IT), they had to remember a predetermined sequence and press the three pads without visual guidance. In a transitional phase between the two conditions, the animals learned to memorize the correct sequence. Auditory instruction signals (tones of different frequencies) told the animal which mode it was in. After the instruction signals, the animals waited for a visual signal that triggered the first movement. 3. Neuronal activity was analyzed during three defined periods: delay period, premovement period, and movement period. Statistical comparisons were made to detect differences between the two behavioral modes with respect to the activity in each period. 4. Most, if not all, of MI neurons exhibited similar activity during the delay, premovement, and movement periods, regardless of whether the sequential motor task was visually guided or internally determined. 5. More than one-half of the SMA neurons were preferentially or exclusively active in relation to IT during both the premovement (55%) and movement (65%) periods. In contrast, PM neurons were more active (55% and 64% during the premovement and movement periods) in VT. 6. During the instructed-delay period, a majority of SMA neurons exhibited preferential or exclusive relation to IT whereas the activity in PM neurons was observed equally in different modes. 7. Two types of neurons exhibiting properties of special interest were observed. Sequence-specific neurons (active in a particular sequence only) were more common in SMA, whereas transition-specific neurons (active only at the transitional phase) were more common in PM. 8. Although a strict functional dichotomy is not acceptable, these observations support a hypothesis that the SMA is more related to IT, whereas PM is more involved in VT. 9. Some indications pointing to a functional subdivision of PM are obtained.

Animals↗