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Haemy Lee, Christian Wallraven; Neuroanatomical correlates of cross-modal transfer performance in object categorization: from vision to touch. Journal of Vision 2015;15(12):361. doi: 10.1167/15.12.361.
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© ARVO (1962-2015); The Authors (2016-present)
Previous behavioral and neuroimaging studies have shown that object shape knowledge acquired in vision or touch can be transferred to the other modality. Studies on cross-modal processing so far, however, have exclusively focused on averaged population data. Here, we investigate individual variability in cross-modal transfer, as well as neuroanatomical correlates of transfer performance based on voxel-based morphometry (VBM). 38 participants underwent a cross-modal categorization task and an anatomical scan. The categorization task started with a training phase, in which participants had to categorize eight novel, parametrically-defined 3D objects into two categories. Participants were trained with feedback until they were correct twice for all objects (randomly presented in blocks). Visual training was followed by a haptic testing phase for ten blocks. From this testing data, we calculated haptic accuracy and – since objects were parametrically-defined – haptic sensitivity from fitted psychometric functions. The results show that participants on average transferred visual knowledge to haptics. Importantly, however, we observed a considerable amount of individual variance in performance measures. Next, we looked for anatomical correlates of this individual variability using VBM. We therefore conducted multiple regressions between haptic performance and regional concentrations of grey-matter using age, gender, and total brain size as nuisance covariates. Regressions were done at the whole-brain level and for selected ROIs known to be involved in multisensory object shape processing. Results showed positive correlations between grey-matter volume and haptic sensitivity for left early somatosensory cortex (BA3) and right inferior-temporal gyrus (a well-known area for visuo-haptic shape processing). In addition, left middle-temporal gyrus (known for multisensory integration and higher-level memory processing) positively correlated with haptic accuracy. Our results underscore the importance of investigating individual differences in multisensory shape processing, suggesting for the first time anatomical correlates of such performance differences that may also be useful for future clinical applications.
Meeting abstract presented at VSS 2015
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