Orienting auditory attention in time: Lateralized alpha power reflects spatio-temporal filtering

Abstract

The deployment of neural alpha (8–12 Hz) lateralization in service of spatial attention is well-established: Alpha power increases in the cortical hemisphere ipsilateral to the attended hemifield, and decreases in the contralateral hemisphere, respectively. Much less is known about humans’ ability to deploy such alpha lateralization in time, and to thus exploit alpha power as a spatio-temporal filter. Here we show that spatially lateralized alpha power does signify – beyond the direction of spatial attention – the distribution of attention in time and thereby qualifies as a spatio-temporal attentional filter. Participants ( N = 20) selectively listened to spoken numbers presented on one side (left vs right), while competing numbers were presented on the other side. Key to our hypothesis, temporal foreknowledge was manipulated via a visual cue, which was either instructive and indicated the to-be-probed number position (70% valid) or neutral. Temporal foreknowledge did guide participants’ attention, as they recognized numbers from the to-be-attended side more accurately following valid cues. In the magnetoencephalogram (MEG), spatial attention to the left versus right side induced lateralization of alpha power in all temporal cueing conditions. Modulation of alpha lateralization at the 0.8 Hz presentation rate of spoken numbers was stronger following instructive compared to neutral temporal cues. Critically, we found stronger modulation of lateralized alpha power specifically at the onsets of temporally cued numbers. These results suggest that the precisely timed hemispheric lateralization of alpha power qualifies as a spatio-temporal attentional filter mechanism susceptible to top-down behavioural goals.

Parkinson's disease affects the neural alpha oscillations associated with speech‐in‐noise processing

“…In contrast, higher speech intensity led to a significant increase of ITPC to sentence onset in the +5-dB SNR compared with the À5-dB SNR condition. This finding is in line with previous research suggesting that auditory evoked ITPC is driven by primary auditory processing and is not modulated by task demands (Wöstmann et al, 2016;Wöstmann et al, 2021).…”

Attentional modulation of beta-power aligns with the timing of behaviorally relevant rhythmic sounds

“…Hence, we demonstrate that rhythmic attentional modulation of neural activity during perception of sound sequences indeed reflects endogenous selection of the most relevant time-points, as the experimental context had simultaneous presentation of distracting stimuli at irrelevant time-points. This is further in line with a recent finding that lateralized alpha power is stronger at the onset of temporally cued stimuli within auditory rhythmic sequences ( Wöstmann et al. 2021 ), as well as the idea that auditory selective attention dynamically adjusts to the temporal structure in behaviorally relevant auditory input streams ( Large and Jones 1999 ).…”

“…Due to the tapping requirement during the initial practice, participants might have engaged in imaginary tapping during the actual experiment, which might explain why beta- and not alpha-band modulations were found in the present study. For example, in a recent study, Wöstmann et al. (2021) presented participants with sequences of spoken digits to both ears, with the instruction to attend to digits in one ear only, as they would have to decide afterwards which of two digits had been presented in the attended stream.…”

Dynamic alpha power modulations and slow negative potentials track natural shifts of spatio‐temporal attention

“…Using a paradigm free from potentially confounding stimulus‐driven alpha power fluctuations and evoked neural responses, we revealed subtle attention‐driven alpha power dynamics, which seemed to be more informative of behavior than the much stronger and more commonly investigated static alpha power lateralization effects. Such dynamic alpha power modulations might constitute a universal mechanism for the flexible prioritization of information at its most relevant moments in time, independent of the sensory modality (van Ede et al., 2011; Wöstmann et al., 2021) and whether the attentional spotlight shines at information in the external or internal space (de Vries et al., 2017; van Ede et al., 2017). Since our paradigm was also designed to minimize decision‐ and motor‐related processing, our finding of slow negative potentials and their non‐trivial correlation with subsequent memory performance further adds to the growing evidence that temporal attention can affect cognitive processes beyond the level of response preparation and execution and suggests that such processes might be reflected by slow negative waves.…”