Poster D61, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Investigating the Temporal Dynamics of Word Processing Using Multiband fMRI
Stephen Bailey1, Laurie Cutting1,2; 1Vanderbilt Brain Institute, Vanderbilt University, 2Vanderbilt Kennedy Center, Vanderbilt University
Reading requires distant areas of the brain to rapidly coordinate, passing along information from visual regions to language processing regions. Research using MEG and EEG suggest that this process occurs in less than half a second, with an initial sweep of visual information, followed by feedback from various other cortical areas (Carreiras et al, 2014). Recent advances in parallel slice acquisition with fMRI enable sub-second temporal resolution, opening up the possibility of studying network dynamics in tasks such as reading. Here, we determined whether the BOLD response, measured at a 600ms sampling rate, could detect temporal differences in the hemodynamic responses of regions involved in word recognition. We acquired 3-4 eight-minute runs of fMRI data from 12 subjects while they completed a word recognition task using sparse event-related presentation. Analysis of the BOLD signal showed, on average, a canonical hemodynamic response among nodes in the language network, with the left inferior frontal gyrus emerging as the key phonological processing region. This contrasted with uniform deactivation among default mode network ROIs across conditions. Across individuals, the hemodynamic response showed the canonical shape; however, there was individual variability in both the mean amplitude and width of the response. Results suggest that multiband fMRI can capture variability in its shape across individuals and trials. Future investigations will address how response properties are related to behavioral indices, such as reading skill, and explore more complex reading tasks such as discourse processing.
Topic Area: LANGUAGE: Lexicon