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Su Keun Jeong, Yaoda Xu; Decoding location and category information in human parietal cortex. Journal of Vision 2012;12(9):1159. doi: 10.1167/12.9.1159.
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© ARVO (1962-2015); The Authors (2016-present)
To understand the neural mechanisms mediating the selection and encoding of multiple visual objects, previous findings showed that the human inferior intra-parietal sulcus (IPS) selects and individuates objects based on location and the superior IPS encodes the feature information from the selected objects. However, it is unclear whether inferior IPS also encode object feature information and whether superior IPS always encode object features regardless of the task demand. To answer these questions, using multivariate pattern analysis, we examined fMRI response patterns for object category and location encoding in inferior and superior IPS. In the first experiment, observers were shown blocks of images from one of four object categories in one of two locations and detected occasional vertical or horizontal movement of the stimuli. We found that inferior IPS response was predominately location based, consistent with its overall role in location-based processing. Interestingly, inferior IPS also showed a small but significant category selectivity. Superior IPS, on the other hand, showed neither location nor category selectivity. To investigate whether the lack of category selectivity in superior IPS was task specific since the motion detection task did not engage any category specific processing, in the second experiment, we asked observers to perform a 1-back object identity repetition detection task. Preliminary results showed that, with this task, superior IPS exhibited significant category selectivity. Taken together, these results indicate that inferior IPS contains strong location selectivity and weak category selectivity even when the encoding of such information was not necessary, supporting its role in automatic visual object individuation. Superior IPS, in contrast, seems to only encode object category information when it is task relevant, suggesting the flexibility of information representation in this brain region.
Meeting abstract presented at VSS 2012
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