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

•We used unihemispheric tACS at alpha vs gamma frequency during dichotic listening.•Alpha-tACS relatively decreased recall of targets contralateral to stimulation.•Gamma-tACS showed the opposite effect on spatial attention compared to alpha-tACS.•Externally amplified oscillations are functionally relevant to spatial attention.