The effect was marginally significant during the stimulus epoch and significant during the selection and reward epochs. It might be argued that the response cells were simply signaling click here two different spatial locations rather than the egocentric response. If that were

the case, we would expect to see roughly equal numbers of cells that signal the two locations in the north (left east and right west) or the two locations in the south (east right and west left). We quantified the number of cells with a significant side × response interaction that fired more in the north or the south and observed 0, 4, and 2 such cells during stimulus, selection, and reward epochs, respectively. In contrast, we observed 3, 10, and 15 response cells during

the same epochs (Table 1), suggesting that these cells encode something other than location, most likely egocentric responses. We were interested in whether differences in patterns of selectivity depended upon the laminar location of cells. Of our 71 criterion cells, 32 were in superficial layers, 18 were in deep layers and the layer of the remaining 21 cells could not be precisely determined. Whether or not a cell showed selectivity for egocentric responses, particular objects, or object-location conjunctions was not influenced by laminar location (Table S2). As might be predicted by connectivity, however, cells in deep layers were more likely to exhibit spatial selectivity (χ2(1) = selleck inhibitor 3.125, p < 0.039). Deep layers are targeted very by subicular input (Kloosterman et al., 2003). In addition, although the posterior parietal cortex projects to superficial and deep layers, the deep layers are preferentially targeted (Burwell and Amaral, 1998a). In general, the proportion of cells showing some type of selectivity differed significantly across epochs (χ2(2) = 12.07, p < 0.002), such that the numbers increased as the trial progressed, from 15 cells during presentation of the

stimulus to 34 and 41 during selection and reward, respectively (Table 1). Numbers of cells exhibiting object and object-location conjunctions were not significantly different across epochs (p = 0.60). Cells showing egocentric response correlates, however, increased significantly across epochs (χ2(2) = 7.79, p < 0.02). Numbers of cells showing location correlates were marginally significantly different across epochs (χ2(2) = 5.71, p < 0.06). Thus, location and response correlates were more evident in the selection and reward epochs. To understand the stability of behavioral correlates, we examined patterns of selectivity across the three epochs. Of the 55 cells that were responsive in at least one epoch, 26 (47%) exhibited selectivity only in a single epoch and 29 (53%) exhibited selectivity in 2 or 3 epochs (Table S3). Of the 29 cells selective in more than one epoch, 11 exhibited similar patterns of selectivity across epochs. Of those, 6 were stable for location, 4 for response, and one for object-location selectivity.