Is activation of the lateral occipital complex during haptic shape perception due to visual imagery?

K. Sathian, Department of Neurology, Emory University School of Medicine

Abstract
The lateral occipital complex (LOC) is shape-selective in both vision and touch and is also active during visual imagery. Previous studies have not established definitively whether or not LOC activation during haptic shape perception is due to visual imagery, or to engagement of a multisensory representation. Here we examined correlations between inter-individual differences in the strength of LOC activity in three different tasks, as measured using functional magnetic resonance imaging (fMRI). Haptic and visual perception of shape evoked overlapping activations in bilateral LOC, with a significant positive correlation in the right LOC between these tasks. Haptic perception and visual imagery of shape also elicited overlapping activations in bilateral LOC; however, correlations between these two tasks tended to be negative, significantly so in the right LOC. These results argue against a mediating role for visual imagery in LOC activation during haptic perception, favoring instead the concept of a modality-independent representation of shape in the LOC.

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