Neural correlates of binding features within- or cross-dimensions in visual conjunction search: an fMRI study.
Neuroimage 2011;
57:235-241. [PMID:
21539923 DOI:
10.1016/j.neuroimage.2011.04.024]
[Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 04/08/2011] [Accepted: 04/12/2011] [Indexed: 11/23/2022] Open
Abstract
The fMRI technique was used to investigate the functional neuroanatomy of binding features within- or cross-dimension during visual conjunction search. Participants were asked to perform feature search (FS; e.g., search for a vertical bar among tilted bars), within-dimension search (WS; e.g., search for an upright T among non-target oriented Ts and Ls), cross-dimension search (CS; e.g., search for an orange vertical bar among blue vertical bars and orange tilted bars), and complex search combining within- and cross-dimension features (WCS; e.g., search for an orange upright T among orange leftward Ts and blue Ls). Reaction times (RTs) taken to decide whether a target was present or absent were faster in the FS than in the WS, CS, and WCS conditions, but did not differ between the latter three conditions. Neuroimaging results revealed a set of fronto-parietal regions, including frontal eye field and intraparietal sulcus, to be consistently activated in conjunction search (WS, CS, and WCS) relative to feature search, suggesting that these regions play a more prominent role in matching visual input against the target template in conjunction search. Furthermore, left occipito-temporal cortex was more activated in within-dimension conjunction search, and bilateral intraparietal sulci were more activated in cross-dimension conjunction search. This suggests that features from the same dimension are 'bound' at a higher stage of the ventral pathway by conjoining the inputs from lower-level neurons, whereas neurons along the intraparietal sulcus appear to be necessary for discerning the presence of cross-dimensional conjunctions.
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