Does alpha phase modulate visual target detection? Three experiments with tACS-phase-based stimulus presentation

DOI

In recent years, the influence of alpha (7–13 Hz) phase on visual processing has received a lot of attention. Magneto-/encephalography (M/EEG) studies showed that alpha phase indexes visual excitability and task performance. Studies with transcranial alternating current stimulation (tACS) aim to modulate oscillations and causally impact task performance. Here, we applied right occipital tACS (O2 location) to assess the functional role of alpha phase in a series of experiments. We presented visual stimuli at different pre-determined, experimentally controlled, phases of the entraining tACS signal, hypothesizing that this should result in an oscillatory pattern of visual performance in specifically left hemifield detection tasks. In experiment 1, we applied 10 Hz tACS and used separate psychophysical staircases for six equidistant tACS-phase conditions, obtaining contrast thresholds for detection of visual gratings in left or right hemifield. In experiments 2 and 3, tACS was at EEG-based individual peak alpha frequency. In experiment 2, we measured detection rates for gratings with (pseudo-)fixed contrast. In experiment 3, participants detected brief luminance changes in a custom-built LED device, at eight equidistant alpha phases. In none of the experiments did the primary outcome measure over phase conditions consistently reflect a one-cycle sinusoid. However, post hoc analyses of reaction times (RT) suggested that tACS alpha phase did modulate RT for specifically left hemifield targets in both experiments 1 and 2 (not measured in experiment 3). This observation requires future confirmation, but is in line with the idea that alpha phase causally gates visual inputs through cortical excitability modulation.

Identifier
DOI https://doi.org/10.34894/I732AY
Metadata Access https://dataverse.nl/oai?verb=GetRecord&metadataPrefix=oai_datacite&identifier=doi:10.34894/I732AY
Provenance
Creator Graaf, Tom de ORCID logo; Thomson, Alix ORCID logo; Janssens, Shanice E. W. (ORCID: 0000-0003-3638-765X); Bree, Sander van ORCID logo; Oever, Sanne ten ORCID logo; Sack, Aleander T. ORCID logo
Publisher DataverseNL
Contributor Graaf, Tom de; faculty data manager FPN
Publication Year 2020
Rights info:eu-repo/semantics/openAccess
OpenAccess true
Contact Graaf, Tom de (Maastricht University); faculty data manager FPN (Maastricht University)
Representation
Resource Type experimental data; Dataset
Format application/zip
Size 3873644
Version 1.0
Discipline Agriculture, Forestry, Horticulture, Aquaculture; Agriculture, Forestry, Horticulture, Aquaculture and Veterinary Medicine; Life Sciences; Social Sciences; Social and Behavioural Sciences; Soil Sciences