Effects of Alpha Oscillatory Power during Presentation of Naturalistic Multisensory Events
Poster Presentation

Simon Kelly
NKI

Daniel Senkowski
NKI

Dave Saint-Amour

John Foxe
NKI

     Abstract ID Number: 180
     Full text: Not available
     Last modified: March 19, 2006
     Presentation date: 06/18/2006 4:00 PM in Hamilton Building, Foyer
     (View Schedule)

Abstract
In a recent study, the temporal dynamics of neural processes involved in cross-modal integration of naturalistic objects in motion were examined through ERP analysis of high-density EEG. A tri-phasic pattern evident in the ERP, showing a temporally stable scalp topography, alluded to the presence of stimulus-evoked oscillations within the alpha (8-14Hz) frequency band. To further investigate, we performed time-frequency analysis on the data contrasting effects of alpha power following each of 6 stimulus types: combined auditory-visual (AV), and the respective unisensory auditory (A) and visual (V) components of both a naturalistic motion stimulus (i.e., a water splash) and a non-naturalistic control stimulus, which were presented in a randomized stream. Evoked alpha power over bilateral occipital cortex observed following visual and multisensory stimulation exhibited a distinctly more inferior topography from that of ongoing alpha power measured from the pre-stimulus period, suggestive of a process distinct from ongoing oscillatory activity. This effect paralleled the previous findings of the tri-phasic ERP pattern and thus suggests an involvement of alpha oscillations in naturalistic multisensory processing. Additionally, a significant desynchronization of parieto-occipital alpha power was observed for naturalistic auditory-alone stimuli but was absent in the non-naturalistic condition. This possibly reflects increased visual imagery following naturalistic auditory stimulation.