Poster E2, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Alpha oscillations during exogenous and endogenous attention in touch
Alexander Jones1, Bettina Forster2; 1Middlesex University London, 2City University London
One of the strongest predictors of attention measured in the brain is the change in alpha oscillations, as measured by electroencephalogram (EEG). Contralateral decreases and ipsilateral increases in power, measured over sensory cortices, in the alpha frequency (8-12Hz) have shown to correlate with shifting attention to a location in space. The present study explored the role of alpha oscillations when expecting a lateralized tactile stimuli in three tasks. In an exogenous task (A) a non-predictive tactile cue to the index finger was followed by a target after 800 ms, presented to the same (cued) or opposite (uncued) finger. In an endogenous task (B) the same stimuli were presented but the cue was informative. If the cue appeared to the left the target was also most likely (80%) to appear to the left. In an endogenous counter-predictive task (C) a left cue indicated a target was most likely (80%) to appear to the right hand. Response times showed inhibition of return in the exogenous task and facilitation of responses by cues to targets in the two endogenous tasks. Wavelet analysis demonstrated a modulation of lateralized alpha oscillations in the endogenous task (B) in the cue-target interval. Interestingly, a similar but reduced lateralized effect was present in the exogenous task (A). In the counter-predictive task (C) there was evidence of competing alpha oscillations resulting from both endogenous and exogenous orienting. Taken together, these findings demonstrate that alpha oscillations relate not only to endogenous but also exogenous shifts of attention.
Topic Area: ATTENTION: Spatial