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  • 1
    Electronic Resource
    Electronic Resource
    Control of arm movement after bilateral lesions of area 5 in the monkey (Macaca mulatta) (1992)
    Springer
    Experimental brain research 90 (1992), S. 229-232 
    Details
    ISSN: 1432-1106
    Keywords: Area 5 lesion ; Proprioceptive discrimination ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of bilateral area 5 lesions on the analysis of proprioceptive information and the guidance of reaching movements was studied in three rhesus monkeys. In the first paradigm (Proprioceptive discrimination test) the monkeys were trained to discriminate between movements of a joystick to the right or left without visual control; they reported the direction of movement by touching or not touching a screen (go/no-go task). After area 5 had been removed, the monkeys were only mildly impaired on this test. It is concluded that such simple joint movement could be analysed in area 2, area 5 being concerned with more complex arm movements. In the second paradigm (Searching test) the monkey had to find a peanut on a board in the dark using proprioceptive information stored in memory during previous trials. After area 5 lesions, the number of correct reaches was not modified but the number of errors after an incorrect trial (correcting movement) was significantly increased. The data suggests that when visual input is not available, area 5 is involved in the guidance of arm movements on the basis of proprioceptive inputs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229277
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The functions of the medial premotor cortex (1995)
    Springer
    Experimental brain research 102 (1995), S. 445-460 
    Details
    ISSN: 1432-1106
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report several studies on the effects of removing the medial premotor cortex (supplementary motor area) in monkeys. The removal of this area alone does not cause either paralysis or akinesia. However, the animals were poor at performing a simple learned task in which they had to carry out an arbitrary action: they were taught to raise their arm in order to obtain food in a foodwell below. They were impaired whether they worked in the light or the dark. They were impaired when they had to perform the movements at their own pace, but much less impaired when a tone paced performance. Monkeys with lesions in the anterior cingulate cortex were as impaired as monkeys with medial premotor lesions at performing this task at their own pace. However, monkeys with lateral premotor lesions were less impaired. We conclude that the medial premotor areas play a crucial role in the performance of learned movements when there is no external stimulus to prompt performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230649
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The functions of the medial premotor cortex (1995)
    Springer
    Experimental brain research 102 (1995), S. 461-473 
    Details
    ISSN: 1432-1106
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Monkeys with medial premotor cortex (MPC) lesions are impaired on a simple learned task that requires them to raise their arm at their own pace. However, they can succeed on this task if they are given tones to guide performance. In the externally paced task the tones could aid performance in several ways. They tell the animal when to act (trigger), they remind the animal that food is available and so motivate (predictor), and they remind the animal of what to do (instruction). Monkeys with MPC lesions can respond quickly to visual cues (experiment 1), and they can respond as well as normal monkeys when there is no immediate trigger (experiment 2). They are also quick to relearn a task in which external cues tell them what to do (experiment 5). However, they are poor at selecting between movements on a simple motor sequence task (experiment 3), and they are poor at changing between two movements (experiment 4). On these tasks there were cues to act as triggers and predictors, but there were no external instructions. We conclude that the reason why animals with MPC lesions perform better with external cues is that these cues act as instructions. The cues prompt retrieval of the appropriate action. This is true whether the task requires the animal to perform one action (experiments 1 and 2) or to select between actions (experiments 3 and 4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230650
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Parietal cortex and movement I. Movement selection and reaching (1997)
    Springer
    Experimental brain research 117 (1997), S. 292-310 
    Details
    ISSN: 1432-1106
    Keywords: Key words Movement selection ; Reaching ; Spatial representation ; Parietal cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recording studies in the parietal cortex have demonstrated single-unit activity in relation to sensory stimulation and during movement. We have performed three experiments to assess the effect of selective parietal lesions on sensory motor transformations. Animals were trained on two reaching tasks: reaching in the light to visual targets and reaching in the dark to targets defined by arm position. The third task assessed non-standard, non-spatial stimulus response mapping; in the conditional motor task animals were trained to either pull or turn a joystick on presentation of either a red or a blue square. We made two different lesions in the parietal cortex in two groups of monkeys. Three animals received bilateral lesions of areas 5, 7b and MIP, which have direct connections with the premotor and motor cortices. The three other animals subsequently received bilateral lesions in areas 7a, 7ab and LIP. Both groups were still able to select between movements arbitrarily associated with non-spatial cues in the conditional motor task. Removal of areas 7a, 7ab and LIP caused marked inaccuracy in reaching in the light to visual targets but had no effect on reaching in the dark. Removal of areas 5, 7b and MIP caused misreaching in the dark but had little effect on reaching in the light. The results suggest that the two divisions of the parietal cortex organize limb movements in distinct spatial coordinate systems. Area 7a/7ab/LIP is essential for spatial coordination of visual motor transformations. Area 5/7b/MIP is essential for the spatial coordination of arm movements in relation to proprioceptive and efference copy information. Neither part of the parietal lobe appears to be important for the non-standard, non-spatial transformations of response selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050224
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  • 5
    Electronic Resource
    Electronic Resource
    Parietal cortex and movement II. Spatial representation (1997)
    Springer
    Experimental brain research 117 (1997), S. 311-323 
    Details
    ISSN: 1432-1106
    Keywords: Key words Area 5 ; Area 7b ; Spatial representation ; Reaching ; Interjoint coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Lesions in the two divisions of parietal cortex, 5/7b/MIP and 7a/LIP, produce dissociable reaching deficits. Monkeys with 5/7b/MIP removals were tested on reaching in the dark under two different conditions. All the reaches made on any day were from the same starting position to the same target position in the control condition. In the “transfer” condition, all the reaches were made to the same target position but consecutive reaches were made from different starting positions. The target could be represented as a constant pattern of joint and muscle positions in the control condition. The transfer condition required a representation of the starting position of the hand and/or a representation of the target in terms of its position in space. Removal of areas 5, 7b and MIP produced only a very mild impairment in the control condition and a severe impairment in the transfer condition. This suggests that 5/7b/MIP does not represent the limb in simple sensory or motor coordinates but in terms of its spatial position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050225
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Cortical areas and the selection of movement: a study with positron emission tomography (1991)
    Springer
    Experimental brain research 84 (1991), S. 393-402 
    Details
    ISSN: 1432-1106
    Keywords: PET ; Blood flow ; Movement ; Premotor areas ; Parietal cortex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Regional cerebral blood flow was measured in normal subjects with positron emission tomography (PET) while they performed five different motor tasks. In all tasks they had to moved a joystick on hearing a tone. In the control task they always pushed it forwards (fixed condition), and in four other experimental tasks the subjects had to select between four possible directions of movement. These four tasks differed in the basis for movement selection. A comparison was made between the regional blood flow for the four tasks involving movement selection and the fixed condition in which no selection was required. When selection of a movement was made, significant increases in regional cerebral blood flow were found in the premotor cortex, supplementary motor cortex, and superior parietal association cortex. A comparison was also made between the blood flow maps generated when subjects performed tasks based on internal or external cues. In the tasks with internal cues the subjects could prepare their movement before the trigger stimulus, whereas in the tasks with external cues they could not. There was greater activation in the supplementary motor cortex for the tasks with internal cues. Finally a comparison was made between each of the selection conditions and the fixed condition; the greatest and most widespread changes in regional activity were generated by the task on which the subjects themselves made a random selection between the four movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231461
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  • 7
    Electronic Resource
    Electronic Resource
    Motor learning in monkeys (Macaca fascicularis) with lesions in motor thalamus (1989)
    Springer
    Experimental brain research 77 (1989), S. 113-126 
    Details
    ISSN: 1432-1106
    Keywords: Thalamus ; Basal ganglia ; Motor learning ; Akinesia ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The study examines the nature of the influence that the basal ganglia exert on frontal cortex via the motor nuclei of the thalamus. Twelve monkeys were trained to pull a handle given one colour cue and to turn it given another. Bilateral lesions were then placed in the ventral thalamus. Four monkeys with large anterior lesions including the VA nucleus and the anterior part of VLo were severely impaired at relearning the task. Monkeys with small lesions in VAmc or with lesions centred on VLo were not impaired. The analysis of the histology suggests that the impairment in the four monkeys did not result from involvement of the cerebellar relay through nucleus X. It is argued that the animals are not impaired because of faulty execution. This suggests that the basal ganglia have an influence on motor learning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250573
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    Paper (German National Licenses)
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