The Role of Alpha Activity in Spatial and Feature-Based Attention.
Modulations in alpha oscillations (∼10 Hz) are typically studied in the context of anticipating upcoming stimuli. Alpha power decreases in sensory regions processing upcoming targets compared to regions processing distracting input, thereby likely facilitating processing of relevant information while suppressing irrelevant. In this electroencephalography study using healthy human volunteers, we examined whether modulations in alpha power also occur after the onset of a bilaterally presented target and distractor. Spatial attention was manipulated through spatial cues and feature-based attention through adjusting the color-similarity of distractors to the target. Consistent with previous studies, we found that informative spatial cues induced a relative decrease of pretarget alpha power at occipital electrodes contralateral to the expected target location. Interestingly, this pattern reemerged relatively late (300-750 ms) after stimulus onset, suggesting that lateralized alpha reflects not only preparatory attention, but also ongoing attentive stimulus processing. Uninformative cues (i.e., conveying no information about the spatial location of the target) resulted in an interaction between spatial attention and feature-based attention in post-target alpha lateralization. When the target was paired with a low-similarity distractor, post-target alpha was lateralized (500-900 ms). Crucially, the lateralization was absent when target selection was ambiguous because the distractor was highly similar to the target. Instead, during this condition, midfrontal theta was increased, indicative of reactive conflict resolution. Behaviorally, the degree of alpha lateralization was negatively correlated with the reaction time distraction cost induced by target-distractor similarity. These results suggest a pivotal role for poststimulus alpha lateralization in protecting sensory processing of target information.
Department of Psychiatry, Academic Medical Center, University of Amsterdam , 1105 AZ, Amsterdam, The Netherlands.
Rosanne M
RM
van Diepen
Center for Mind and Brain, University of California Davis, Davis, CA 95616, USA; Department of Neurobiology, Physiology, & Behavior, University of California Davis, Davis, CA 95616, USA.
Lee M
LM
Miller
School of Psychology, University of Birmingham , Birmingham, B15 2TT, United Kingdom.
Ali
0000-0001-5732-7555
A
Mazaheri
Center for Mind and Brain, University of California Davis, Davis, CA 95616, USA; Department of Psychology, University of California Davis, Davis, CA 95616.
Joy J
0000-0001-5663-9637
JJ
Geng
D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology*; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D011930:Reaction Time; D013826:Theta Rhythm; D055815:Young Adult
alpha; attention; feature; poststimulus; spatial