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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 72 (1988), S. 237-248 
    ISSN: 1432-1106
    Keywords: Premotor cortex ; Supplementary motor cortex ; Area 6 ; Neuronal activity ; Motor set
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We compared neuronal activity in the premotor (PM) and supplementary motor cortex (SM) of two rhesus monkeys as they performed two tasks. In an externally-instructed task, a visuospatial instruction stimulus indicated which of two touch pads should be the target of a forelimb movement. In an internally-instructed task, the visuospatial stimulus was either irrelevant or not presented, but in either case the target alternated between the two touch pads in blocks of 20 trials each. In both tasks, the monkey withheld movement for a self-timed delay period. Neuronal activity modulation during the delay period (set-related activity) and immediately before movement (movement-related activity) was comparable in PM and SM, both in terms of the proportion of cells with both of those activity patterns and their depth of modulation. Thus, our findings do not provide strong support for a clear-cut functional division between PM and SM regarding the control of externally- and internally-instructed limb movements. Within PM, 57 out of 96 cells with set-related activity showed similar modulation during the two tasks, supporting the proposition that such activity contributes to the preparation for a limb movement. In 32 of the 39 PM set-related neurons that showed a significant activity difference between the two tasks, activity was greater in the externally-instructed task. This finding supports the hypothesis that set-related activity in PM contributes more to sensorially-instructed than to other movements.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 69 (1988), S. 327-343 
    ISSN: 1432-1106
    Keywords: Premotor cortex ; Frontal lobe ; Area 6 ; Motor preparation ; Motor set
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We compared set-related premotor cortex activity in two conditional motor tasks. In both tasks, a rhesus monkey moved its forelimb to one of two possible targets on the basis of visuospatial instruction stimuli. One target was located to the left of the limb's starting position, the other to the right. In the directional task, a white light situated within the target provided the instruction. In the arbitrary task, colored instruction stimuli equidistant from the targets established an arbitrary relationship between stimulus and response. One hypothesis about setrelated premotor cortex activity is that it contributes to the preparation for limb movement on the basis of sensory instruction stimuli. If set-related activity differed profoundly in the arbitrary and directional tasks, then that hypothesis would be untenable. Out of 403 task-related premotor cortex neurons in two monkeys, 130 neurons showed set-related activity, and we studied 118 cells in detail. The vast majority (81%) of these 118 neurons showed no significant difference between the two tasks in set-related activity. When set-related activity did differ, the greatest activity usually occurred after arbitrary instructions; the opposite being the case for only 5% of our sample. Differences in activity during the two tasks, even when statistically significant, were generally small. The present results accord with the hypothesis that set-related premotor cortex activity reflects aspects of motor preparation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 60 (1985), S. 188-191 
    ISSN: 1432-1106
    Keywords: Premotor cortex ; Movement-related neurons ; Hindlimb ; Forelimb ; Topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single cell recordings were made from the premotor cortex (lateral part of area 6) of a monkey trained to perform either a distal hindlimb or forelimb movement separately. Out of 175 movement-related neurons, 59 neurons showed modulation of activity only prior to the hindlimb movement, and the majority of them was distributed in a focal region around the superior precentral sulcus, several mm posteromedial to the genu of the arcuate sulcus. The hindlimb focus was separate from a focal region for forelimb movement-related neurons, which lay immediately posterior to the genu of the arcuate sulcus.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 77 (1989), S. 245-256 
    ISSN: 1432-1106
    Keywords: Premotor cortex ; Area 6 ; Neuron-alactivity ; Topographic organization ; Motor cortex ; Motor set ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal activity was studied in the premotor cortex (PM) of two rhesus monkeys, each of which performed both forelimb and hindlimb movements. On each trial, the monkey received a visual instruction stimulus (IS) that indicated whether a foot or a hand movement would be rewarded on that trial. After a delay period, during which the monkey withheld an overt movement, a visual trigger stimulus (TS) was presented to indicate that the monkey should execute a movement. Of 572 task-related neurons recorded in PM, 149 neurons showed set-related activity, defined as a significant increase or decrease in discharge rate throughout most of the instructed delay period, and 299 neurons showed movement-related activity, defined as a significant change in discharge rate between the TS and movement onset. Both setand movement-related activity were subdivided into three patterns: activity modulation 1) before a foot movement only (“foot” neurons); 2) before a hand movement only (“hand” neurons); and 3) before both foot and hand movements (“mixed” neurons). The distribution of set-related neurons mostly overlapped with that of movement-related neurons, although set-related neurons were located in more restricted regions than movement-related neurons. “Foot” neurons with setand movementrelated activity were distributed near the superior precentral sulcus. “Hand” neurons were mainly located lateral to the “foot“ neurons with some overlap. The results indicate that most PM setand movement-related neurons contribute, respectively, to the preparation for and execution of specific limb movements, as opposed to movement per se. Further, the differential distribution of neurons with activity related to hindlimb vs. forelimb movement supports previous indications that PM is topographically organized.
    Type of Medium: Electronic Resource
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