Fast and reliable detection of the functional activation of MT and V6 during coherent motion processing with EEG.

In the adult brain the perception of coherent visual motion (optic flow) activates a network of regions, in particular V5 (MT) and V6, which are part of the dorsal stream. These regions are already active in infants, well before the full development of V1, possibly due to the evolutionary relevance of detecting approaching stimuli or navigating in space. An alteration in the development of the visual dorsal stream and its functions, including motion perception, seems to be a key characteristic of children with Learning Disabilities (LD), an account known as the “dorsal stream vulnerability theory”. According to this view, the early functional integrity of the dorsal stream could be considered as a predictive biomarker of LD. To date, however, most studies on the neural underpinnings of optic flow used fMRI, a method practically unsuitable for studying pediatric populations. Here we tested whether we could reliably use electroencephalography (EEG) for the same aim. We designed a frequency-tagging paradigm alternating flow and random motion stimuli and tested it on adult participants. The results revealed a robust EEG response to coherent motion, detectable at the single subject level within just 4 minutes of recordings. Source reconstruction using EEG-anatomy co-registration and individual structural MR scans confirmed that the cortical areas underlying the EEG activation included V5(MT) and V6. These results set the methodological standard for future studies on pediatric/clinical populations aimed at investigating the neurophysiological underpinning of coherent motion perception.