| Voluntary control of multisaccade gaze shifts during movement preparation and execution. | |
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MedLine Citation:
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PMID: 20164397 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Although the nature of gaze control regulating single saccades is relatively well documented, how such control is implemented to regulate multisaccade gaze shifts is not known. We used highly eccentric targets to elicit multisaccade gaze shifts and tested the ability of subjects to control the saccade sequence by presenting a second target on random trials. Their response allowed us to test the nature of control at many levels: before, during, and between saccades. Although the saccade sequence could be inhibited before it began, we observed clear signs of truncation of the first saccade, which confirmed that it could be inhibited in midflight as well. Using a race model that explains the control of single saccades, we estimated that it took about 100 ms to inhibit a planned saccade but took about 150 ms to inhibit a saccade during its execution. Although the time taken to inhibit was different, the high subject-wise correlation suggests a unitary inhibitory control acting at different levels in the oculomotor system. We also frequently observed responses that consisted of hypometric initial saccades, followed by secondary saccades to the initial target. Given the estimates of the inhibitory process provided by the model that also took into account the variances of the processes as well, the secondary saccades (average latency approximately 215 ms) should have been inhibited. Failure to inhibit the secondary saccade suggests that the intersaccadic interval in a multisaccade response is a ballistic stage. Collectively, these data indicate that the oculomotor system can control a response until a very late stage in its execution. However, if the response consists of multiple movements then the preparation of the second movement becomes refractory to new visual input, either because it is part of a preprogrammed sequence or as a consequence of being a corrective response to a motor error. |
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Authors:
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Arjun Ramakrishnan; Snehal Chokhandre; Aditya Murthy |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-02-17 |
Journal Detail:
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Title: Journal of neurophysiology Volume: 103 ISSN: 1522-1598 ISO Abbreviation: J. Neurophysiol. Publication Date: 2010 May |
Date Detail:
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Created Date: 2010-05-12 Completed Date: 2010-08-25 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375404 Medline TA: J Neurophysiol Country: United States |
Other Details:
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Languages: eng Pagination: 2400-16 Citation Subset: IM |
Affiliation:
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National Brain Research Centre, Nainwal More, Haryana, India. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adolescent Adult Computer Simulation Eye Movement Measurements Humans Likelihood Functions Models, Neurological* Monte Carlo Method Motor Activity / physiology Neuropsychological Tests Probability Psychomotor Performance / physiology* Reaction Time Reproducibility of Results Saccades / physiology* Stochastic Processes Time Factors Volition / physiology Young Adult |
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