Anatomical and physiological evidence suggest that posterior cingulate cortex (CGp) participates in sensorimotor transformations. CGp is strongly connected with visual and premotor cortical areas, and CGp neurons respond following saccades. Previous studies suggest that the activity of CGp neurons is modulated by the position of the eye in the orbit, as well as by saccade direction and amplitude. The -first goal of this project is to fully quantify the spatial and temporal properties of CGp neurons by studying single CGp neurons while monkeys (M. mulatta) perform saccadic trials with or without a delay intervening between target onset and movement onset. This intervening delay allows for a temporal separation of neuronal responses to the target and to the movement. The next goal is to determine whether CGp encodes spatial information in a coordinate frame anchored to the fovea, head, or world. Single CGp neurons are studied while monkeys perform delayed-saccade trials from different initial fixation positions to targets positioned along an axis passing through the previously-mapped neuronal response field (RF). If the movement vector accounts for the variance in firing rate a retinotopic coordinate framework may be used in CGp. If the final eye position is most important, CGp could be using framework anchored to the head or world. Differentiating between these possibilities requires comparing activity on this task before and after rotating the monkey with respect to the visual targets. Preliminary data suggest that CGp encodes information in a coordinate framework centered on the head or world rather than in one that is retinotopic.
| Dean, Heather L; Platt, Michael L (2006) Allocentric spatial referencing of neuronal activity in macaque posterior cingulate cortex. J Neurosci 26:1117-27 |
