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Founded: 1989
ISSN 0898-929X
E-ISSN 1530-8898
2011 Impact Factor: 5.175
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Access provided by YORK UNIVERSITY LIBRARIES
March 2013, Vol. 25, No. 3, Pages 436-454
Posted Online January 30, 2013.
(doi:10.1162/jocn_a_00318)
© 2013 Massachusetts Institute of Technology
Neural Activity in Superior Parietal Cortex during Rule-based Visual-motor TransformationsKara M. Hawkins, Patricia Sayegh, Xiaogang Yan, J. Douglas Crawford, and Lauren E. SergioYork University, Toronto, Canada
Cognition
allows for the use of different rule-based sensorimotor strategies, but
the neural underpinnings of such strategies are poorly understood. The
purpose of this study was to compare neural activity in the superior
parietal lobule during a standard (direct interaction) reaching task,
with two nonstandard (gaze and reach spatially incongruent) reaching
tasks requiring the integration of rule-based information. Specifically,
these nonstandard tasks involved dissociating the planes of reach and
vision or rotating visual feedback by 180°. Single unit activity, gaze,
and reach trajectories were recorded from two female Macaca mulattas.
In all three conditions, we observed a temporal discharge pattern at
the population level reflecting early reach planning and on-line reach
monitoring. In the plane-dissociated task, we found a significant
overall attenuation in the discharge rate of cells from deep recording
sites, relative to standard reaching. We also found that cells modulated
by reach direction tended to be significantly tuned either during the
standard or the plane-dissociated task but rarely during both. In the
standard versus feedback reversal comparison, we observed some cells
that shifted their preferred direction by 180° between conditions,
reflecting maintenance of directional tuning with respect to the reach
goal. Our findings suggest that the superior parietal lobule plays an
important role in processing information about the nonstandard nature of
a task, which, through reciprocal connections with precentral motor
areas, contributes to the accurate transformation of incongruent sensory
inputs into an appropriate motor output. Such processing is crucial for
the integration of rule-based information into a motor act.
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