Rainer Goebel

25 septembre 2015

Psychology and Neuroscience, Maastricht Brain Imaging Centre, Maastricht University, Maastricht, The Netherlands

Cracking mesoscopic coding principles in the human brain with ultra-high field MRI

invité par Sylvain Takerkart


Abstract

Ultra-high magnetic field (UHF) scanners (7 Tesla and higher) provide the possibility to study the functional organisation of the human brain at the level of cortical columns and cortical layers. First progress in this direction has been achieved by revealing individual topographic columnar-level orientation maps in human primary visual cortex, frequency maps in primary auditory cortex and axis-of-motion maps in area hMT/V5. In an extension to multi-sensory stimuli, we revealed that increased spatial resolution at 7 Tesla leads to a better segregation of unimodal and heteromodal voxels in the superior temporal gyrus and planum temporale. More recently, also cognitive tasks have been investigated at the mesoscopic level. We, for example, relate the content of perception during perceptual switches of ambiguous motion stimuli (Plaids) to dynamic activation changes in direction-selective columns in area hMT/V5. Furthermore, we reveal that top-down effects in visual tasks operate on supragranular cortical layers in area V1, which is compatible with predictive coding theories. The presented studies demonstrate that the achievable mesoscopic level of investigation (columns and layers) offered by UHF fMRI allows to map columnar-level features within specialized brain areas as well as revealing layer-specific functional bottom-up and top-down connectivity. Furthermore, mesoscopic fMRI establishes an important bridge to invasive animal research, especially to optical imaging and electrical neuronal population recordings.

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