Motor Cortical Activity in a Context-Recall Task

Pellizzer, Giuseppe; Sargent, P. A.; Georgopoulos, Apostolos P.

doi:10.1126/science.7624802

Cited by 66 publications

(40 citation statements)

References 10 publications

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“…Although consistent with our predictions, these observations are not signiªcant for our model because they take place just preceding and during movement. Cells with activities intermediate between the stimulus and movement direction become active during the "mental rotation task" (Georgopoulos, 1995;Pellizzer et al, 1995). This is in general agreement with our model; however, very little complete time course data have been published, so direct comparison is not possible.…”

Section: Discussionsupporting

confidence: 85%

National Institutes of Mental Health

2014

Encyclopedia of Special Education

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Abstracts Features of virtually all voluntary movements are represented in the primary motor cortex. The movements can be ongoing, imminent, delayed, or imagined. Our goal was to investigate the dynamics of movement representation in the motor cortex. To do this we trained a fully recurrent neural network to continually output the direction and magnitude of movements required to reach randomly changing targets. Model neurons developed preferred directions and other properties similar to real motor cortical neurons. The key ªnding is that when the target for a reaching movement changes location, the ensemble representation of the movement changes nearly monotonically, and the individual neurons comprising the representation exhibit strong, nonmonotonic transients. These transients serve as internal recurrent signals that force the ensemble representation to change more rapidly than if it were limited by the time constants of individual neurons. These transients, if they exist, could be observed in experiments that require only slight modiªcations of the standard paradigm used to investigate movement representation in the motor cortex. s

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Section: Discussionsupporting

confidence: 85%

National Institutes of Mental Health

2014

Encyclopedia of Special Education

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“…Importantly, in the primate, M1 is involved in spatial processing during motor imagery. 18 In addition, M1 can participate in the processing of both serial order information 111,112 and taskrelated spatial information, 113 whereas in humans it can be modulated by attention 114 and has the capacity to store short-term procedural information, 115 implying motor imagery may involve generation of motor representations without movement. 92 Yet, despite differences in both subject selection and baseline tasks, the secondary motor structures, normally involved in motor learning, preparation, programming and memorizing, 36 have consistently shown activation.…”

Section: Functional Imagingmentioning

confidence: 99%

Motor Imagery

Sharma

Pomeroy²,

Baron³

2006

Stroke

607

288

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Background and Purpose-Understanding brain plasticity after stroke is important in developing rehabilitation strategies.Active movement therapies show considerable promise but depend on motor performance, excluding many otherwise eligible patients. Motor imagery is widely used in sport to improve performance, which raises the possibility of applying it both as a rehabilitation method and to access the motor network independently of recovery. Specifically, whether the primary motor cortex (M1), considered a prime target of poststroke rehabilitation, is involved in motor imagery is unresolved. Summary of Review-We review methodological considerations when applying motor imagery to healthy subjects and in patients with stroke, which may disrupt the motor imagery network. We then review firstly the motor imagery training literature focusing on upper-limb recovery, and secondly the functional imaging literature in healthy subjects and in patients with stroke. Conclusions-The review highlights the difficulty in addressing cognitive screening and compliance in motor imagery studies, particularly with regards to patients with stroke. Despite this, the literature suggests the encouraging effect of motor imagery training on motor recovery after stroke. Based on the available literature in healthy volunteers, robust activation of the nonprimary motor structures, but only weak and inconsistent activation of M1, occurs during motor imagery. In patients with stroke, the cortical activation patterns are essentially unexplored as is the underlying mechanism of motor imagery training. Provided appropriate methodology is implemented, motor imagery may provide a valuable tool to access the motor network and improve outcome after stroke.

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“…The neural correlates of visuomotor memory scanning were investigated recently [18]. A monkey was trained to exert a force pulse on a 2-D semi-isometric manipulandum in eight different directions.…”

Section: The Neural and The Mental: Memory Scanningmentioning

confidence: 99%

The mental and the neural: Psychological and neural studies of mental rotation and memory scanning

Georgopoulos

Pellizzer

1995

Neuropsychologia

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Abstract--In this article we review studies pertaining to psychophysical measurements and neural correlates of tasks requiring the processing of directional information in spatial motor tasks. The results of psychological studies in human subjects indicate that time-consuming processes underlie mental rotation and memory scanning. Other studies have suggested that these processes may rely on different basic mechanisms. A direct insight into their neural mechanisms was obtained analyzing the activity of single cells and neuronal populations in the brain of behaving monkeys performing the same tasks. These studies revealed the nature of the neural processes underlying mental rotation and memory scanning and confirmed their different nature.Key Words: motor cortex; mental rotation; memory scanning; directional processing; spatial transformations. THE PROBLEMA basic question in cognitive neuroscience is the elucidation of neural mechanisms underlying cognitive processing. A common strategy to address this problem is to record aspects of neural activity (e.g. impulse activity of neurons, slow potentials, electroencephalogram) or other signals related to it (e.g. regional brain blood flow) during performance of a cognitive task: Then, changes in the relevant variable in a particular brain area during task performance is taken to indicate a relation of that area to the task in question. This approach has resulted in important insights but it falls short of providing a direct description of the cognitive process in terms of a brain process, since it relies essentially on temporal associations alone. Ideally, the neural data should be such that the cognitive process could be constructed from them as it unfolds in time, and be identified and distinguished from other possible processes that could also lead to a successful performance of the particular task. We investigated two cognitive processes with this objective in mind, namely mental rotation and memory scanning.

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Motor Cortical Activity in a Context-Recall Task

Cited by 66 publications

References 10 publications

National Institutes of Mental Health

National Institutes of Mental Health

Motor Imagery

The mental and the neural: Psychological and neural studies of mental rotation and memory scanning

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