Complementary contributions of the cerebellum and temporo-parietal cortex to object-related VT integration

Yavor Yalachkov, Institute of Medical Psychology (IMP), and Brain Imaging Center (BIC), Johann Wolfgang Goethe-University, Frankfurt am Main, Germany

Abstract
It is widely accepted that object-related visuo-tactile integration (VTI) in humans prominently involves regions in temporal and parietal cortex, namely the lateral occipital complex (LOC) and the intra-parietal sulcus (IPS; see Amedi et al., 2005 for a review of the imaging literature). Here, we used fMRI to identify brain regions within the human VTI network coding for the side of tactile stimulation and/or the degree of VT congruency (related to object orientation or object identity). Wooden 3D objects (so-called ‘fribbles’) were presented either unimodally (V; T) or in various bimodal (VT) combinations. In addition, we controlled for potential cue and motor confounds using a ‘no-stimulus’ baseline condition. VTI effects (i.e., activations to each of the unimodal conditions [V>0; T>0] and stronger activations to bimodal as compared to unimodal stimulations [VT]) were found in a bilateral network of brain regions including LOC, anterior IPS, and the cerebellum. Activation was higher during incongruent as compared to congruent VT stimulation in LOC and aIPS, but not in the cerebellum. On the other hand, LOC showed no and aIPS only a slight (contralateral) hand preference, while VTI in the cerebellum was more pronounced during stimulation of the ipsilateral as compared to the contralateral hand.

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