Purchase this article with an account.
Katherine Bettencourt, Yaoda Xu; Retinotopically defined parietal regions and their relationship to parietal areas involved in object individuation and identification. Journal of Vision 2011;11(11):245. doi: 10.1167/11.11.245.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Based on results from visual short-term memory (VSTM) studies, Xu and Chun (2009) recently proposed a neural object file theory, arguing that visual objects are first selected based on their spatial/temporal information (object individuation), after which their features are encoded (object identification). These two processes are dissociated within intraparietal sulcus (IPS), such that inferior IPS, an area at the junction of the transverse occipital sulcus and the bottom of IPS, is responsible for object individuation, while superior IPS is more involved in object identification. IPS has also been subdivided into at least five separate regions based on retinotopic mapping (Swisher et al., 2007; Konen and Kastner, 2008). However, as of yet, no one has been able to answer the critical question of what functional distinctions exist between these retinotopic regions. Moreover, the degree of overlap between these regions and the IPS regions described in Xu and Chun (2009) remains unclear. As retinotopic regions are prime candidates to support spatial indexing and selection mechanisms, inferior IPS likely lies within the lower IPS regions. However, as superior IPS tracks the amount of visual information encoded, regardless of location, this region may lie outside of these maps. Consistent with this view, Sheremata et al. (2010) showed that VSTM activity co-localizes with retinotopic mapping in early IPS regions, but deviates from it in superior and anterior regions. Here, we performed separate inferior and superior IPS localizers, as in Xu and Chun (2009), and compared this data on an individual subject basis to retinotopically defined IPS0-4 regions. The majority of the inferior IPS region was actually found within V3A, with some overlap with IPS0. The superior IPS region, however, was localized primarily in IPS2. These results provide new insights into the functional distinctions among the different retinotopic maps seen along the dorsal visual pathway.
This PDF is available to Subscribers Only