However, given the strength of data supporting a role for parietal cortex in both forms of spatial processing, it seems likely that Selleck Veliparib ultimately our understanding

of how parietal cortex supports spatial behaviour will integrate these functions. For example, parietal cortex may serve as a selective visuomotor controller, transforming neural signals that code the positions of salient or behaviourally relevant stimuli into body-centered frames of reference useful for motor control (Lacquaniti et al., 1995; Buneo et al., 2002; Buneo & Andersen, 2006). This is in keeping generally with the idea that spatial information must pass through a processing bottleneck at the point where sensory representations are converted into motor representations, because sensory systems typically

represent many more stimuli than can be effectively or advantageously used to control motor output. From that perspective, sensorimotor control implies attention, or a selective sensorimotor transformation. Visual awareness (e.g. attention) may be a product, at least to some degree, of this bottleneck, in the sense that we are most aware of those stimuli that we intend to move or respond to. As reviewed above, damage to parietal cortex manifests as a diverse set of spatial problems, producing deficits that range from visuomotor control to spatial attention to spatial cognition, many of which now have identified Pexidartinib in vitro physiological correlates at the level of single neurons in parietal cortex. This diversity of spatial impairments undoubtedly reflects the fact that the neural representations of space Low-density-lipoprotein receptor kinase instantiated by the activity of parietal neurons are integral to an enormous range of thoughts and actions. From the data considered above an overall homology between the PPC of the monkey and that of man emerges when comparing the SPL across the two species, although an expansion

of the IPL has certainly occurred. The conclusion nonetheless that considerable homology exists between monkey and human SPL stems not only from comparative architectonic analyses but also from the analysis of the parcellation of parietal cortex based on corticocortical connectivity in both species. This has become possible thanks to studies using axoplasmic tracers in monkeys and, more recently, probabilistic tractography from diffusion tensor imaging in humans. However, homology does not imply identity. For instance, fMRI studies (for a review see Orban et al., 2004) suggest that, together with areas that are similar in the two species, a number of higher-order intraparietal areas that are not present in monkeys have emerged during human evolution. These areas belong to the visuomotor processing stream involved in coding action space (see also Simon et al., 2002).