title: Optical imaging of visually guided reaching in macaque posterior parietal cortex.
abstract: Sensorimotor transformation for reaching movements in primates requires a large network of visual, parietal, and frontal cortical areas. We performed intrinsic optical imaging over posterior parietal cortex including areas 7a and the dorsal perilunate in macaque monkeys during visually guided hand movements. Reaching was performed while foveating one of nine static reach targets; thus eye-position-varied concurrently with reach position. The hemodynamic reflectance signal was analyzed during specific phases of the task including pre-reach, reach, and touch epochs. The eye position maps changed substantially as the task progressed: First, direction of spatial tuning shifted from a weak preference close to the center to the lower eye positions in both cortical areas. Overall tuning strength was greater in area 7a. Second, strength of spatial tuning increased from the early pre-reach to the later touch epoch. These consistent temporal changes suggest that dynamic properties of the reflectance signal were modulated by task parameters. The peak amplitude and peak delay of the reflectance signal showed considerable differences between eye position but were similar between areas. Compared with a detection task using a lever response, the reach task yielded higher amplitudes and longer delays. These findings demonstrate a spatially tuned topographical representation for reaching in both areas and suggest a strong synergistic combination of various feedback signals that result in a spatially tuned amplification of the hemodynamic response in posterior parietal cortex.
authors: Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, 197 University Avenue, Newark, NJ, 07102, USA, barbara@cortex.rutgers.edu.
authors: Barbara
authors: B
authors: Heider
authors: Ralph M
authors: RM
authors: Siegel
mesh_terms: D000818:Animals; D001931:Brain Mapping; D007091:Image Processing, Computer-Assisted; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D009068:Movement / Q000502:physiology; D061848:Optical Imaging; D010296:Parietal Lobe / Q000033:anatomy & histology* / Q000502:physiology*; D010812:Physical Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D012044:Regression Analysis; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors; D014794:Visual Fields / Q000502:physiology*