Region-specific modulations in oscillatory alpha activity serve to facilitate processing in the visual and auditory modalities Ali Mazaheri a, ⁎, Martine R. van Schouwenburg b,c,f , Andrew Dimitrijevic d , Damiaan Denys a,e , Roshan Cools b,c , Ole Jensen c a Department of Psychiatry, Academic Medical Center, University of Amsterdam, The Netherlands b Radboud University Medical Centre Nijmegen, Department of Psychiatry c Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging d Communication Sciences Research Center, Cincinnati Children's Hospital, Department of Otolaryngology, University of Cincinnati e Netherlands Institute for Neuroscience (DD), Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands f Department of Neurology, University of California, San Francisco, California abstract article info Article history: Accepted 25 October 2013 Available online 2 November 2013 There have been a number of studies suggesting that oscillatory alpha activity (~10 Hz) plays a pivotal role in attention by gating information flow to relevant sensory regions. The vast majority of these studies have looked at shifts of attention in the spatial domain and only in a single modality (often visual or sensorimotor). In the current magnetoencephalography (MEG) study, we investigated the role of alpha activity in the suppression of a distracting modality stream. We used a cross-modal attention task where visual cues indicated whether partic- ipants had to judge a visual orientation or discriminate the auditory pitch of an upcoming target. The visual and auditory targets were presented either simultaneously or alone, allowing us to behaviorally gauge the “cost” of having a distractor present in each modality. We found that the preparation for visual discrimination (relative to pitch discrimination) resulted in a decrease of alpha power (9–11 Hz) in the early visual cortex, with a con- comitant increase in alpha/beta power (14–16 Hz) in the supramarginal gyrus, a region suggested to play a vital role in short-term storage of pitch information (Gaab et al., 2003). On a trial-by-trial basis, alpha power over the visual areas was significantly correlated with increased visual discrimination times, where- as alpha power over the precuneus and right superior temporal gyrus was correlated with increased audi- tory discrimination times. However, these correlations were only significant when the targets were paired with distractors. Our work adds to increasing evidence that the top–down (i.e. attentional) modulation of alpha activity is a mechanism by which stimulus processing can be gated within the cortex. Here, we find that this phenomenon is not restricted to the domain of spatial attention and can be generalized to other sensory modalities than vision. © 2013 Elsevier Inc. All rights reserved. Introduction Attention involves selective facilitation of relevant sensory input and suppression of irrelevant sensory input. Oscillatory activity in the alpha range (~10 Hz) has been proposed to play a pivotal mechanistic role in attention by gating information flow to relevant sensory regions through the inhibition of irrelevant regions (Foxe et al., 1998; Jensen and Mazaheri, 2010; Klimesch et al., 2007). Supporting this hypothesis are a number of studies reporting that oscillations in the alpha range are sup- pressed in brain regions processing attended information, but enhanced in regions processing unattended information (Bauer et al., 2012a,b; Haegens et al., 2011a, 2012; Jokisch and Jensen, 2007; Medendorp et al., 2007; Rihs et al., 2007; Romei et al., 2008a; Thut et al., 2003). Although the mechanism underlying alpha enhancement in directing functional inhibition is not fully understood some recent work demon- strates that alpha oscillations exercise a strong inhibitory influence on both spike timing and firing rate of neural activity (Haegens et al., 2011b; Mazaheri and Jensen, 2010). The majority of studies that have examined the role of alpha oscilla- tions and attention have used shifts of attention (often spatial) within one modality (often visual or sensory–motor). There have been compar- atively fewer studies examining the influence of auditory spatial atten- tion on alpha lateralization in the occipital parietal regions (e.g. Banerjee et al., 2011; Fu et al., 2001; Kerlin et al., 2010). This discrepancy can in part be attributed to skepticism about the existence of alpha power modulation by auditory attention that is distinct from the visual or sensory-motor systems (see (Weisz et al., 2011) for a review of this debate). Furthermore, previous research has suggested that the detec- tion of an auditory alpha rhythm is difficult at the scalp level due to the NeuroImage 87 (2014) 356–362 ⁎ Corresponding author. E-mail address: ali.mazah@gmail.com (A. Mazaheri). 1053-8119/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.neuroimage.2013.10.052 Contents lists available at ScienceDirect NeuroImage journal homepage: www.elsevier.com/locate/ynimg