Neural impact of the semantic content of visual mental images and visual percepts

A. Mazard, L. Laou, M. Joliot, E. Mellet
Cognitive Brain Research. 2005-08-01; 24(3): 423-435
DOI: 10.1016/j.cogbrainres.2005.02.018

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1. Brain Res Cogn Brain Res. 2005 Aug;24(3):423-35. Epub 2005 Apr 8.

Neural impact of the semantic content of visual mental images and visual

Mazard A(1), Laou L, Joliot M, Mellet E.

Author information:
(1)Groupe d’Imagerie Neurofonctionnelle, UMR 6194, GIP Cyceron, Bd H. Becquerel,
BP 5229, 14074 CAEN Cedex, France.

The existence of hemispheric lateralization of visual mental imagery remains
controversial. In light of the literature, we used fMRI to test whether
processing of mental images of object drawings preferentially engages the left
hemisphere to compared non-object drawings. An equivalent comparison was also
made while participants actually perceived object and non-object drawings.
Although these two conditions engaged both hemispheres, activation was
significantly stronger in the left occipito-temporo-frontal network during mental
inspection of object than of non-object drawings. This network was also activated
when perception of object drawings was compared to that of non-object drawings.
An interaction was nonetheless observed: this effect was stronger during imagery
than during perception in the left inferior frontal and the left inferior
temporal gyrus. Although the tasks subjects performed did not explicitly require
semantic analysis, activation of this network probably reflected, at least in
part, a semantic and possibly a verbal retrieval component when object drawings
were processed. Mental imagery tasks elicited activation of early visual cortex
at a lower level than perception tasks. In the context of the imagery debate,
these findings indicate that, as previously suggested, figurative imagery could
involve primary visual cortex and adjacent areas.

DOI: 10.1016/j.cogbrainres.2005.02.018
PMID: 16099355 [Indexed for MEDLINE]

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