: The general goal or this research is to understand the neural mechanisms underlying spatial cognition and to investigate the role of the right hemisphere in this function. For that purpose, rhesus monkeys will be trained to perform tasks commonly used to determine the spatial capacities of adult human subjects and children during development. These tasks include memorizing locations of visual stimuli, categorizing space explicitly (e.g. """"""""high""""""""/""""""""low""""""""), making comparative spatial judgments (e.g. about """"""""higher/lower""""""""), estimating relative distances (with respect to a reference point, or not), and using Cartesian coordinate axes. Each monkey will be trained in all tasks. The activity of single cells during task performance will be recorded in posterior parietal cortex using 16-microelectrode systems. Posterior parietal cortex is known to be intimately involved in spatial operations and, therefore, we expect cell activity to be modulated involved in the aforementioned tasks and to provide valuable Information concerning their neural mechanisms. In addition, we will test the hypothesis that parietal cortex in the right hemisphere is specialized for spatial operations, a hypothesis based on the differential effects of brain damage on spatial abilities of human patients. For that purpose, we will record simultaneously from symmetric posterior parietal sites of the two hemispheres during performance of all the tasks. The data to be obtained will be analyzed using uni- and multivariate statistical methods to determine the control of these tasks by singe cells and neuronal populations, and to delineate the specific contribution of each one of the cortical areas above to this control. By analyzing normal brain mechanisms, we hope to discover some basic principles of organization underlying spatial deficits observed in brain-damaged people.
| Merchant, Hugo; Crowe, David Andrew; Robertson, Melissa S et al. (2011) Top-down spatial categorization signal from prefrontal to posterior parietal cortex in the primate. Front Syst Neurosci 5:69 |
| Averbeck, Bruno B; Crowe, David A; Chafee, Matthew V et al. (2009) Differential contribution of superior parietal and dorsal-lateral prefrontal cortices in copying. Cortex 45:432-41 |
| Merchant, Hugo; Naselaris, Thomas; Georgopoulos, Apostolos P (2008) Dynamic sculpting of directional tuning in the primate motor cortex during three-dimensional reaching. J Neurosci 28:9164-72 |
| Crowe, David A; Averbeck, Bruno B; Chafee, Matthew V (2008) Neural ensemble decoding reveals a correlate of viewer- to object-centered spatial transformation in monkey parietal cortex. J Neurosci 28:5218-28 |
| Georgopoulos, Apostolos P; Karageorgiou, Elissaios (2008) Neurostatistics: applications, challenges and expectations. Stat Med 27:407-17 |
| Georgopoulos, Apostolos P; Stefanis, Costas N (2007) Local shaping of function in the motor cortex: motor contrast, directional tuning. Brain Res Rev 55:383-9 |
| Chafee, Matthew V; Averbeck, Bruno B; Crowe, David A (2007) Representing spatial relationships in posterior parietal cortex: single neurons code object-referenced position. Cereb Cortex 17:2914-32 |
| Georgopoulos, Apostolos P; Merchant, Hugo; Naselaris, Thomas et al. (2007) Mapping of the preferred direction in the motor cortex. Proc Natl Acad Sci U S A 104:11068-72 |
| Naselaris, Thomas; Merchant, Hugo; Amirikian, Bagrat et al. (2005) Spatial reconstruction of trajectories of an array of recording microelectrodes. J Neurophysiol 93:2318-30 |
| Chafee, Matthew V; Crowe, David A; Averbeck, Bruno B et al. (2005) Neural correlates of spatial judgement during object construction in parietal cortex. Cereb Cortex 15:1393-413 |
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