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Rapid motor responses are appropriately tuned to the metrics of a visuospatial task.
- Source :
-
Journal of neurophysiology [J Neurophysiol] 2008 Jul; Vol. 100 (1), pp. 224-38. Date of Electronic Publication: 2008 May 07. - Publication Year :
- 2008
-
Abstract
- Considerable research has established that rapid motor responses (traditionally called reflexes), can be modified by a subject's voluntary goals. Here, we expand on past observations using verbal instructions by defining the voluntary goal via visual target position. This approach allowed us to objectively enforce task adherence and explore a richer set of variables, such as target direction and distance, metrics that modify voluntary control and that--according to our hypothesis--will influence rapid motor responses. Our first experiment tested whether upper-limb responses are categorically modulated by target direction by placing targets such that the same perturbation could push the hand into one target and out of the other, a spatial analogue to "resist/yield" verbal instructions. Consistent with these classical results, we found that the short-latency rapid response (R1, 20-45 ms) was not modulated by target direction, whereas long-latency rapid responses (R2/R3, 45-105 ms) were modified in a manner approaching the voluntary response (VOL, 120-180 ms). Our second experiment tested whether upper-limb responses are continuously modulated by target distance by distributing five targets along one axis centered on the hand. Here, the long-latency and voluntary response mirrored the task demands by increasing activity in a graded fashion with increasing target distance. Our final experiment explored how upper-limb responses incorporate two-dimensional spatial information by placing targets radially around the hand. Notably, long-latency responses exhibited smooth tuning functions to target direction that were similar to those observed for the voluntary response. Taken together, these results illustrate the flexibility of long-latency rapid responses and emphasize their similarity to later voluntary responses.
- Subjects :
- Adult
Biomechanical Phenomena
Electromyography
Female
Humans
Male
Muscle, Skeletal innervation
Muscle, Skeletal physiology
ROC Curve
Reaction Time physiology
Upper Extremity innervation
Eye Movements physiology
Mental Processes physiology
Psychomotor Performance physiology
Reflex physiology
Space Perception physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-3077
- Volume :
- 100
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of neurophysiology
- Publication Type :
- Academic Journal
- Accession number :
- 18463184
- Full Text :
- https://doi.org/10.1152/jn.90262.2008