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Andrew Heinz, Jeffrey Johnson; Load-Dependent Increases in Alpha-Band Power: Relevance to Sensory Cortex Excitability and Distractor Interference. Journal of Vision 2015;15(12):297. doi: 10.1167/15.12.297.
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© ARVO (1962-2015); The Authors (2016-present)
Studies exploring the role of neural oscillations in cognition have revealed sustained increases in alpha-band power (ABP) during the delay period of verbal and visual short-term memory (STM) tasks. There have been various proposals regarding the functional significance of such increases, including the inhibition of task-irrelevant cortical areas, and the active retention of information in STM. The present study examines the role of delay-period ABP in mediating the effects of distractor interference in STM. Specifically, we reasoned that, if load-dependent ABP increases represent the gating of sensory inputs, they should be associated with modulations of the visual evoked potential (VEP) elicited by a task-irrelevant probe presented during the delay interval. Previous results from our lab (Heinz & Johnson, VSS 2014) failed to find this predicted relationship. However, we suspect that the complicated nature of the design may have obscured possible effects. Using a simplified design for the present study, we recorded the electroencephalogram (EEG) while subjects performed a change detection task requiring the retention of two or four novel shapes. Importantly, on a portion of trials, a task-irrelevant bilateral checkerboard probe was presented during the delay interval. Our analysis focused on examining correlations between load-dependent increases in ABP and the magnitude of both the P1 and N1 ERP components. Results revealed that reductions in the amplitude of both the P1 and N1 were predicted by load-dependent increases in ABP prior to the probe. Additionally, for the P1, the load-dependent amplitude change predicted load-dependent differences in the disruptive effect of the probe on STM capacity. This same pattern was not observed for the N1. We conclude that load-dependent increases in ABP may play a role in gating task-irrelevant sensory inputs during STM maintenance. Ongoing analyses are examining the potential role of frontal feedback in mediating these effects.
Meeting abstract presented at VSS 2015
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