Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Interference on neural mechanisms for working memory maintenance
Julia C. Beck1, Peter S. Whitehead1, Marty G. Woldorff1; 1Duke University
We must often maintain information in working memory (WM) while attending to unrelated tasks and stimuli. However, the neural processes underlying WM maintenance in the face of attentional interruptions is relatively unexplored. Here, we used contralateral delay activity (CDA) – a sustained, posterior, negative-polarity ERP index of active maintenance of WM representations – to investigate the effect of visual and cognitive interruptions on such maintenance. Participants were presented with a lateralized array of colors and asked to maintain them in WM. During the delay period before the WM probe, in separate blocks, participants either attended and responded to a Flanker task stimulus, or ignored the stimulus. Behaviorally, high performance was observed on the Flanker task (93%) and on WM performance in Flanker-attended (85%) and Flanker-ignored (89%) conditions. We observed that the CDA was initially similar after WM array presentation, but terminated sooner prior to relevant Flanker stimuli, suggesting some WM withdrawal when expecting a cognitive task to perform. The Flanker stimulus disrupted the CDA in both conditions, but with interactions between lateralized sensory effects and the hemisphere of WM maintenance. Critically, the CDA never reinstantiated in the second delay period even following ignored Flanker stimuli, with an inverted, positive CDA (CDAp) following attended Flanker stimuli. We conclude that the CDAp resulted from the suppression of lateralized components of the Flanker stimuli while maintaining the fidelity of the WM representation. Moreover, high WM performance without reinstantiation of the CDA suggests WM content can remain accurate without an active posterior CDA process.
Topic Area: EXECUTIVE PROCESSES: Working memory