Poster Session B, Sunday, March 24, 8:00 – 10:00 am, Pacific Concourse
Modulation of Phase Synchronization across Fronto-Parietal and Temporal Cortices during Auditory Attention
Fahimeh Mamashli1,2, Samantha Huang1,2, Sheraz Khan1,2, Matti Hämäläinen1,2,3, Jyrki Ahveninen1,2; 1Athinoula A. Martinos Center for Biomedical Imaging, MGH/HST, Charlestown, MA, USA, 2Department of Radiology, MGH, Harvard Medical School, Boston, MA, USA, 3Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
Many studies have documented modulations of auditory cortex (AC) when a human subject pays attention to sounds originating in one location of space while actively ignoring other sources. These modulations are presumably driven by an executive network of fronto-parietal cortex regions. However, the oscillatory dynamics of functional connections among brain areas activated during auditory attention has remained elusive. In this study we acquired magnetoencephalography (MEG) data during a dichotic auditory selective attention task. In 10-s trials, the subjects (N=15) were (a) cued to detect a harmonic target sound embedded among standard tones presented to one ear and (b) asked to ignore standard tones and occasional task-irrelevant novel sounds presented in the opposite ear. We applied a novel approach, particularly developed for functional connectivity analysis in time and frequency among subregions of broader regions of interest (ROI), to analyze functional connectivity in our cortically-constrained MEG source estimates. Phase coherences were estimated between three ROIs: AC, frontal and parietal cortices. We found that in comparison to the novel sounds, target detection increased gamma band functional connectivity between inter-hemispheric and intra-hemispheric ROIs in later time windows (>300 ms). In contrast, alpha band functional connectivity was increased in earlier time windows for novel in comparison to target sounds. Our results suggest that suppression of irrelevant auditory events vs. voluntary attention to relevant auditory targets increase functional connectivity at different oscillatory frequency bands.
Topic Area: ATTENTION: Auditory