Hemispatial neglect is a disorder of spatial processing characterized by inability to attend to stimuli
situated contralateral to lesions affecting the parietal cortex. Hemispatial neglect is a poor prognostic indicator following stroke. Critically, while neglect is often marked by loss of attention to visual or somatosensory stimuli, clinical tests in which patients replicate simple figures or draw from memory reveal that neglect is a disorder not of information storage or attainment, but of spatial processing. Specifically, while spatial information may be stored or represented on an allocentric coordinate system, it must be mapped onto egocentric coordinates in a process which depends on the posterior parietal cortex. Indeed, lesion studies in humans as well as in rodents have revealed the importance of this region in the expression of neglect. However, more recent work has revealed that spatial processing requires a distributed network and a number of connected regions are also implicated in neglect. Lesion studies by their nature are limited by the static permanence of the lesions. We sought to create an inducible model of hemispatial neglect using stereotactic delivery of AAV-halorhodopsin to the posterior parietal cortex in mice, permitting the reversible optical silencing of this region by light. We show that in the presence of green light delivered via an optic fiber, mice develop a rightward bias. We will next utilize this inducible model of neglect while recording from large numbers of neurons in the dorsal hippocampus or prefrontal cortex to understand how the PPC influences spatial processing during goal-directed navigation.