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Jonathan S. Cant, Stephen R. Arnott, Melvyn A. Goodale; Functionally and anatomically distinct regions for processing form and texture in the human ventral stream revealed by fMR-adaptation. Journal of Vision 2007;7(9):329. doi: https://doi.org/10.1167/7.9.329.
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© ARVO (1962-2015); The Authors (2016-present)
In a previous study (Cant & Goodale, 2007) we demonstrated that attending to an object's form and attending to that same object's surface properties (particularly texture) engages functionally and anatomically distinct regions of occipito-temporal cortex. Specifically, attending to form activated the lateral occipital area (LO), whereas attending to texture activated the parahippocampal gyrus (PG) and collateral sulcus (CoS). Although these regions seemed to be specialized for processing one particular stimulus dimension (e.g. form in area LO), the pattern of results observed in each ‘specialized’ region demonstrated that there was also activation to the other, non-preferred stimulus dimensions (e.g. texture in area LO). This led us to question whether the activation to texture in area LO, for example, represented texture processing per se, or represented activation to changes in form while people were attending to texture. To investigate these possibilities, we conducted an fMR-adaptation experiment which allowed us to examine the response properties of regions specialized for processing form, texture, and colour when participants were not explicitly attending to a particular stimulus dimension. Participants passively viewed blocks where only one dimension varied (form, texture, or colour) and blocks where no dimensions varied, while fixating a cross in the centre of the display. Area LO was most sensitive to variations in form, whereas the PG and CoS were most sensitive to variations in texture. As in our previous study, no regions were found that were more sensitive to variations in colour compared to other dimensions. Taken together, these results replicate the findings from our previous study but also suggest that area LO, the PG, and CoS can respond in a very stimulus-driven manner in the absence of task-dependent manipulations of attention. Furthermore, these results provide additional evidence for the functional and anatomical separation of form and texture processing in occipito-temporal cortex.
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