Poster F46, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Alpha-Band Power: Relevance to Visual Short-Term Memory Maintenance and Ongoing Visual Sensory Processing.
Andrew Heinz1, Jeffrey Johnson1; 1North Dakota State University
Studies exploring the role of neural oscillations in cognition have revealed sustained increases in alpha-band power (ABP) during the delay period of visual short-term memory (STM) tasks. There have been various proposals regarding the functional relevance of these increases, including the inhibition of task-irrelevant processes, and the active retention of information in STM. The present study attempts to reconcile these alternatives by recording EEG while participants performed a delayed recall task in which they were required to maintain the orientation of a single Gabor patch across a delay. In the primary experiment, a second task-irrelevant Gabor was presented mid-way through the delay. We then used a forward encoding model to derive orientation-specific channel tuning functions (CTFs). We reasoned that, if the distributed pattern of delay-period ABP reflects the mnemonic information supporting recall in this task, item identity should be decodable from this distributed pattern both prior to and following the presentation of the distractor. Additionally, if this pattern reflects inhibition of task-irrelevant visual processing, the magnitude of the global distractor-evoked response (GMFP) should differ as a function of CTF amplitude and dispersion. Our results were consistent with both of these hypotheses; item identity was decodable throughout the retention interval, whether a distractor was presented or not, and decoding ability was predictive of the distractor evoked response. These findings provide further evidence suggesting that delay-period ABP supports STM maintenance by selectively inhibiting task-irrelevant features along the task-relevant dimension.
Topic Area: EXECUTIVE PROCESSES: Working memory