Parietal alpha tACS shows inconsistent effects on visuospatial attention

Coldea, Andra, Stephanie Morand, Domenica Veniero, Monika Harvey, and Gregor Thut. 2021. ‘Parietal alpha tACS shows inconsistent effects on visuospatial attention’, Plos one, 16(8).

Summary: In the literature, alpha-tACS has been shown to shift attention away from the contralateral towards the ipsilateral visual field. During this replication study, Coldea et al. applied left parietal alpha-tACS (10 Hz) during an attentional task and found no changes in task performance or resting-state EEG with respect to sham. The authors call for more tACS replication studies to understand the factors that contribute to tACS efficacy, such as stimulation intensity and duration. Although numerous studies have used tACS to successfully modulate neural oscillations and behavior, it is equally important to carefully consider studies, such as this one, that demonstrate limits of tACS.
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Pros:
● Included resting-state EEG immediately following stimulation to account for artifacts present during stimulation
● Successful blinding of participants to alpha-tACS vs sham
​● Use of an attentional task where tACS successfully modulated performance in a past study

Open questions:
● How do tACS intensity and stimulation duration change effects?
● Does individualized peak frequency alpha-tACS enhance effects?
●Are there changes in EEG during the task which are obscured by the extensive artifacts introduced with stimulation?
●Would accuracy changes with alpha-tACS have been found if participants had not performed so close to ceiling (average accuracy of 95%)?

Contributed by: Amber McFerren