Other fMRI studies confirmed the pointing/reach-selective activity in the precuneus region but reported additional brain areas with selective activity for reaching such as the inferior parietal lobule (IPL), the superior parietal lobule (SPL), the medial intraparietal sulcus (mIPS), and a region lateral to the precuneus called the parieto-occipital junction (POJ) (Astafiev et al., 2003; Cavina-Pratesi et al., 2010; Filimon et al., PI3K inhibitor 2009; Prado et al., 2005). Therefore, multiple areas in the human PPC appear to be a putative

homolog of the monkey PRR. These putative homologs of the monkey PRR coincide with, or are in the vicinity of, common lesion sites observed in OA patients (Culham et al., 2006). Perenin and Vighetto (1988) originally suggested that the common lesion sites in OA patients were the IPS, the SPL, and the IPL. A more recent lesion overlap analysis with a large number of unilateral OA patients Microtubule Associated inhibitor revealed three somewhat different foci, one in the precuneus, one in the superior occipital gyrus near the POJ, and one in the SPL (Culham et al., 2006; Karnath and Perenin, 2005). As such, multiple areas implicated for OA overlap with the putative human PRR. Prado et al. (2005) proposed that OA patients who have deficits

when reaching to peripheral targets but not to central targets have lesions specifically in the POJ. This proposal was based on their observation that the POJ was activated only when the reach was made to a peripheral target, while the mIPS was activated during a reaching task regardless of whether the reach target appeared in central old or peripheral vision. In line with this proposal, repetitive TMS in humans over a region near the POJ/precuneus (named “superior parietal occipital cortex”) impaired reaches to peripheral targets, with reaches ending short of the targets (Vesia et al., 2010). This deficit is very similar to the effect of our monkey PRR inactivation, providing further evidence for the functional

similarity between the human precuneus/POJ and the monkey PRR. However, our inactivation site is more anterior and lateral to the precuneus/POJ region. Although homologous areas in the human and monkey brains may not always topographically correspond to each other, the topological discrepancy calls for further functional, anatomical, and cytoarchitectural comparisons between the two areas (Mantini et al., 2012). Foveal reaches differ from extrafoveal reaches in at least two main aspects: the foveal capture of the target and an accompanying saccade to the target. At present, it is unknown if only one of the two or both contribute to the lack of PRR inactivation effect on foveal reaches. However, if the monkey PRR is functionally similar to the human POJ, the foveal capture of the target is probably the determinant (Prado et al., 2005).