In our case, it also allowed us to use the

entire data set for each cell rather than looking only at the peak of the tuning curves, as is the case in the matrix analysis (although see also Figure S2). Selleckchem EX-527 However, it has the disadvantage that the data are forced into a prespecified model, which may not be appropriate. For example, the relative coding of hand, gaze, and target position observed in dorsal premotor cortex and revealed through SVD and gradient analyses (Pesaran et al., 2006) would most likely have appeared intermediate and difficult to interpret if analyzed through a modeling framework restricted to combinations of gaze and hand-centered tuning only. BYL719 purchase In agreement with recent results from other groups, we did observe some heterogeneity at the single-cell level in area 5d and relatively few “purely” hand-centered cells. Although the results of the modeling analysis show a clear peak at weight values associated with a hand-centered

reference frame, there are also cells with intermediate and gaze-centered reference frames (Figure 6). Conversely, others have observed a consistent bias toward gaze-centered coding in PRR (Chang and Snyder, 2010) and hand-centered coding in area 5d (McGuire and Sabes, 2011) but chose to focus on the population of intermediate cells. Hence, much of the data are consistent across groups despite differences in interpretation. A longstanding model of sensorimotor integration postulates a common, gaze-centered, reference frame gain modulated by eye, head, and limb postural signals to enable read-out in multiple reference frames of (Andersen et al., 1998). Advantages of this include a reduction in the number of sequential transformations necessary (for example, from gaze to limb directly, rather than gaze to head to body to limb), parsimonious incorporation

of error signals generated from visual feedback, and computational benefits from using the same reference frame for reaches as for saccades. A more recent approach casts parietal neurons as jointly encoding a set of basis functions with no single underlying reference frame but instead many different combinations of intermediate reference frames (Pouget and Snyder, 2000). The number of cells required for the basis set would increase exponentially with the number of different signals to be integrated. Taken to its extreme, this theory would predict that the signals involved in sensorimotor transformations would be extremely distributed across a large, heterogeneous area and systematic reference frames from region to region would not be observed. This theory is not consistent with what we report here for area 5d or what has previously been reported for PRR.