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Florence Rémy, Nathalie Vayssière, Laure Saint-Aubert, Emmanuel Barbeau, Michèle Fabre-Thorpe; The anterior parahippocampal cortex processes contextual incongruence in a scene. Journal of Vision 2013;13(9):1064. doi: 10.1167/13.9.1064.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction Through visual experience, objects are encoded in association with particular contexts, and these associations probably help the rapid categorization of objects presented in natural scenes since categorization is impaired when objects are seen in incongruent vs. congruent contexts (Joubert et al. 2008). In the visual ventral pathway, the anterior part of the parahippocampal cortex (PHC) may process the relationship between objects and their context (Aminoff et al. 2007, Goh et al. 2004). Correlations between fMRI activity in anterior PHC and object categorization impairment due to contextual incongruence were investigated in the present study. Methods Young (n=14 age range 20-30) and old subjects (n=17, age >60) were scanned using fMRI, while performing a 2-button rapid object (animal vs furniture) categorization task. Animal- or furniture-objects were embedded in congruent or incongruent contexts and were briefly presented (100ms). An ROI in the anterior PHC was defined as a 10-mm radius sphere around coordinates previously reported (Goh et al. 2004). Results As previously shown, object categorization was less accurate (-4.4%, p<0.0002) and slower (+12ms, p<0.00001) in incongruent vs. congruent contexts. This impairment was greater in old (-6.3%, +17ms) than in young (-2.1%, +7ms) subjects. An increase of activity due to incongruence was observed bilaterally in the anterior PHC. The large spread of behavioral impairment values allowed for optimal assessment of correlation between behavioral scores and cerebral activity. A significant correlation was seen between the increase of anterior PHC activity and global categorization impairment (p<0.05) mainly explained by the RT increase (p<0.02). Conclusion Our results reinforce the role of the anterior PHC in processing contextual associations between objects and scenes. Incongruent associations may require additional neural processing relative to congruent ones (previously encoded through experience). Performance impairment in object processing due to contextual incongruence may be specifically related with additional processing in anterior PHC.
Meeting abstract presented at VSS 2013
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