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Neuroimage. 2017 Nov 15;162:257-268. doi: 10.1016/j.neuroimage.2017.09.002. Epub 2017 Sep 6.

The role of auditory cortex in the spatial ventriloquism aftereffect.

Author information

1
Biological Psychology and Neuropsychology, University of Hamburg, 20146 Hamburg, Germany. Electronic address: bjoern.zierul@uni-hamburg.de.
2
Biological Psychology and Neuropsychology, University of Hamburg, 20146 Hamburg, Germany.
3
Department of Neurology, Otto-von-Guericke University, 39120 Magdeburg, Germany.
4
Biological Psychology and Neuropsychology, University of Hamburg, 20146 Hamburg, Germany; Department of Cognitive, Linguistic & Psychological Sciences, Brown University, Providence, RI 02912, USA.
5
Institute of Biological Psychology, Otto-von-Guericke University, 39106 Magdeburg, Germany; Center for Behavioural and Brain Sciences, 39120 Magdeburg, Germany.

Abstract

Cross-modal recalibration allows the brain to maintain coherent sensory representations of the world. Using functional magnetic resonance imaging (fMRI), the present study aimed at identifying the neural mechanisms underlying recalibration in an audiovisual ventriloquism aftereffect paradigm. Participants performed a unimodal sound localization task, before and after they were exposed to adaptation blocks, in which sounds were paired with spatially disparate visual stimuli offset by 14° to the right. Behavioral results showed a significant rightward shift in sound localization following adaptation, indicating a ventriloquism aftereffect. Regarding fMRI results, left and right planum temporale (lPT/rPT) were found to respond more to contralateral sounds than to central sounds at pretest. Contrasting posttest with pretest blocks revealed significantly enhanced fMRI-signals in space-sensitive lPT after adaptation, matching the behavioral rightward shift in sound localization. Moreover, a region-of-interest analysis in lPT/rPT revealed that the lPT activity correlated positively with the localization shift for right-side sounds, whereas rPT activity correlated negatively with the localization shift for left-side and central sounds. Finally, using functional connectivity analysis, we observed enhanced coupling of the lPT with left and right inferior parietal areas as well as left motor regions following adaptation and a decoupling of lPT/rPT with contralateral auditory cortex, which scaled with participants' degree of adaptation. Together, the fMRI results suggest that cross-modal spatial recalibration is accomplished by an adjustment of unisensory representations in low-level auditory cortex. Such persistent adjustments of low-level sensory representations seem to be mediated by the interplay with higher-level spatial representations in parietal cortex.

KEYWORDS:

Audiovisual ventriloquism aftereffect; Cross-modal learning; Cross-modal recalibration; Functional magnetic resonance imaging; Psychophysiological interaction; Spatial hearing

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