Wilke, Melanie and Kagan, Igor and Andersen, Richard A. (2012) Functional imaging reveals rapid reorganization of cortical activity after parietal inactivation in monkeys. Proceedings of the National Academy of Sciences of the United States of America, 109 (21). pp. 8274-8279. ISSN 0027-8424 http://resolver.caltech.edu/CaltechAUTHORS:20120614-104017141
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Impairments of spatial awareness and decision making occur frequently as a consequence of parietal lesions. Here we used event-related functional MRI (fMRI) in monkeys to investigate rapid reorganization of spatial networks during reversible pharmacological inactivation of the lateral intraparietal area (LIP), which plays a role in the selection of eye movement targets. We measured fMRI activity in control and inactivation sessions while monkeys performed memory saccades to either instructed or autonomously chosen spatial locations. Inactivation caused a reduction of contralesional choices. Inactivation effects on fMRI activity were anatomically and functionally specific and mainly consisted of: (i) activity reduction in the upper bank of the superior temporal sulcus (temporal parietal occipital area) for single contralesional targets, especially in the inactivated hemisphere; and (ii) activity increase accompanying contralesional choices between bilateral targets in several frontal and parieto-temporal areas in both hemispheres. There was no overactivation for ipsilesional targets or choices in the intact hemisphere. Task-specific effects of LIP inactivation on blood oxygen level-dependent activity in the temporal parietal occipital area underline the importance of the superior temporal sulcus for spatial processing. Furthermore, our results agree only partially with the influential interhemispheric competition model of spatial neglect and suggest an additional component of interhemispheric cooperation in the compensation of neglect deficits.
|Additional Information:||© 2012 National Academy of Sciences. Freely available online through the PNAS open access option. Contributed by Richard A. Andersen, March 29, 2012 (sent for review July 26, 2011). Published online before print May 4, 2012. We thank Dr. D. Procissi for helpwith scanning; Dr. F. Ye for providing the source code for the phase labeling for additional coordinate encoding echo-planar imaging sequence; K. Pejsa and N. Sammons for animal care; Dr. V. Shcherbatyuk for computer support; and Drs. W. Vanduffel, A. Gerits, and J. Bonaiuto for comments on the manuscript. This work was supported by the Moore Foundation, the National Eye Institute, the National Science Foundation, the Defense Advanced Research Projects Agency, and the Boswell Foundation. Author contributions: M.W., I.K., and R.A.A. designed the experiments; M.W. and I.K. conducted the experiments and analyzed the data; M.W., I.K., and R.A.A. wrote the paper.|
|Subject Keywords:||extinction; hemispheric imbalance; saccadic decision; recovery|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||18 Jun 2012 15:32|
|Last Modified:||26 Dec 2012 15:20|
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