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Ryan W Kasper, Scott T Grafton, Miguel P Eckstein, Barry Giesbrecht; Multimodal neuroimaging evidence for the contribution of the medial temporal lobe to modulations of electrophysiological indices of attention during contextual cueing. Journal of Vision 2013;13(9):303. doi: https://doi.org/10.1167/13.9.303.
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Contextual cueing is a facilitation of visual search performance that can result from the repetition of target and distractor spatial configurations (Chun & Jiang, 1998). Neuropsychological and fMRI studies have implicated the medial temporal lobe memory system (Giesbrecht et al, 2012; Greene et al, 2007; Manelis & Reder, 2012) while electrophysiological studies have implicated visual attention systems by showing that the N2pc ERP component is modulated by context (Johnson et al, 2007). However, based on this evidence alone, it remains unclear to what extent these patterns of hemodynamic and electrophysiological neural responses are linked. To investigate this issue, twelve subjects performed a visual search task (256 trials, 50% repeated configurations) in two sessions that were separated by one week. In the first session, 64-channel EEG and whole-brain fMRI data were acquired simultaneously. In the second session, 64-channel EEG was recorded in isolation. Analysis of the behavior indicated a robust RT enhancement for repeated contexts in both sessions (p <0.03). The neuroimaging data were analyzed by first identifying regions of frontal, occipital, parietal, and MTL cortex showing a significant BOLD response to the search task, and then using the locations of those activations to constrain the position of dipoles in an EEG source analysis of the difference between the N2pc ERP component evoked by repeated and novel contexts. The explanatory power of each source was quantified by calculating the change in explained variance when each source was removed from the analysis. This analysis revealed that relative to a random permutation test, the MTL made the most significant contribution to explaining the variance in N2pc modulations by contextual cueing in both sessions (p <0.02). This finding indicates that the MTL memory system may be a critical mediator in the attentional enhancements observed in contextual cueing.
Meeting abstract presented at VSS 2013
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