Format

Send to

Choose Destination
Brain Stimul. 2018 Jul - Aug;11(4):752-758. doi: 10.1016/j.brs.2018.04.006. Epub 2018 Apr 6.

Opposite effects of lateralised transcranial alpha versus gamma stimulation on auditory spatial attention.

Author information

1
Department of Psychology, University of Lübeck, Lübeck, Germany. Electronic address: malte.woestmann@uni-luebeck.de.
2
Experimental Psychology Lab, Center for Excellence "Hearing4all", European Medical School, University of Oldenburg, Oldenburg, Germany.
3
Department of Psychology, University of Lübeck, Lübeck, Germany.

Abstract

BACKGROUND:

Spatial attention relatively increases the power of neural 10-Hz alpha oscillations in the hemisphere ipsilateral to attention, and decreases alpha power in the contralateral hemisphere. For gamma oscillations (>40 Hz), the opposite effect has been observed. The functional roles of lateralised oscillations for attention are currently unclear.

HYPOTHESIS:

If lateralised oscillations are functionally relevant for attention, transcranial stimulation of alpha versus gamma oscillations in one hemisphere should differentially modulate the accuracy of spatial attention to the ipsi-versus contralateral side.

METHODS:

20 human participants performed a dichotic listening task under continuous transcranial alternating current stimulation (tACS, vs sham) at alpha (10 Hz) or gamma (47 Hz) frequency. On each trial, participants attended to four spoken numbers on the left or right ear, while ignoring numbers on the other ear. In order to stimulate a left temporo-parietal cortex region, which is known to show marked modulations of alpha power during auditory spatial attention, tACS (1 mA peak-to-peak amplitude) was applied at electrode positions TP7 and FC5 over the left hemisphere.

RESULTS:

As predicted, unihemispheric alpha-tACS relatively decreased the recall of targets contralateral to stimulation, but increased recall of ipsilateral targets. Importantly, this spatial pattern of results was reversed for gamma-tACS.

CONCLUSIONS:

Results provide a proof of concept that transcranially stimulated oscillations can enhance spatial attention and facilitate attentional selection of speech. Furthermore, opposite effects of alpha versus gamma stimulation support the view that states of high alpha are incommensurate with active neural processing as reflected by states of high gamma.

KEYWORDS:

Alpha; Auditory; Gamma; Neural oscillation; Spatial attention; Transcranial alternating current stimulation

PMID:
29656907
DOI:
10.1016/j.brs.2018.04.006
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center