The prefrontal cortex, particularly the dorsolateral area 8A, is thought to play a role in transforming visual signals into goal-directed behavior. Neurons within this area exhibit visual, motor, and visuomotor responses during oculomotor tasks. We have recently described two types of neurons within the area that have receptive fields (RFs) located in the contralateral and ipsilateral visual hemifields relative to the recorded hemisphere. Whether these neurons show variation in the complexity of their RF remains unclear. Here we recoded the responses of 81 neurons in area 8A of a Macaca fascicularis while the animal made visually-guided saccades to a peripheral sine-wave grating stimulus positioned at one of 40 possible locations (8 equidistant directions arranged along 5 concentric circles). To characterize the visual and motor RFs, we integrated the average firing rate at each location over a 200-millisecond time window during stimulus presentation (visual field) and prior to saccade onset (motor field). 28 percent of neurons showed visual and motor responses. 48 neurons had contralateral-preferring and 27 ipsilateral-preferring visual receptive fields. We observed that visual and motor field size ranged from narrow, directed 'hotspots' to large, diffuse spots spanning both hemifields. Furthermore, we found that a higher proportion of contralateral cells exhibited very small or no shift from visual to motor field center, while ipsilateral cells often displayed greater disparity between their motor and visual field centers. Finally, comparison of the number of peaks in the RFs of ipsilateral and contralateral neurons revealed that motor fields of ipsilateral neurons had more peaks than those of contralateral neurons (p< 0.05, Wilcoxon rank-sum). These findings show that ipsilateral neurons have more complex motor field properties compared to contralateral ones, implying different roles for these neuronal types in the transformation of visual information into gaze commands within area 8A. Meeting abstract presented at VSS 2015.
