Modulating brain oscillations results in altered cognition



 

 

 

 

 

 

Modulating brain oscillations results in altered cognition

 

Recently, transcranial alternating current stimulation (tACS) has been introduced to directly modulate rhythmic brain activity by the application of oscillatory currents. Until now, the efficiency of tACS in modulating rhythmic brain activity has been mainly indicated by inference from the perceptual and behavioural consequences. We delivered tACS over the occipital cortex of 10 healthy participants to entrain the neuronal oscillations in their individual alpha frequency range and compared results with those from a separate group of participants receiving sham stimulation. The tACS but not the sham stimulation elevated EEG alpha power. The results demonstrate the ability of tACS to modulate oscillatory brain activity at a specific frequency. In addition, we tested how auditory perception depends upon the phase of a tACS-evoked alpha oscillation. Short sine tones were embedded in white noise at seven different signal-to-noise ratios. Fitting psychophysical  functions to the data revealed that the detection threshold depended upon the phase of the evoked oscillation. This demonstrates how important the phase of an oscillation is for perception and that tACS can modulate human cognition.

11:58 | 14.11.2011
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