The current thinking is that it’s an electrical effect.
Brain activity consists of intricate patterns of electrical activity, created as neurons process and transmit information. tACS, the method used here, creates electric fields inside the head, which interacts with neurons’ own electrical activity. The effects are pretty subtle—-it can’t make a neuron spike on its own and thus release neurotransmitter. However, it can shift the timing of spikes caused by its “natural” activity”, and thus change those activity patterns.
(My group looks at this in animal and computational models, where we can measure this directly).
The effects turn out to be pretty complicated because other ongoing brain activity shapes the stimulation effect (and vice versa). Sometimes, the same stimulation can even produce totally opposite effects.
Elsewhere in the thread, I linked to an article we wrote about this and other challenges for doing (useful) brain stimulation.
Brain activity consists of intricate patterns of electrical activity, created as neurons process and transmit information. tACS, the method used here, creates electric fields inside the head, which interacts with neurons’ own electrical activity. The effects are pretty subtle—-it can’t make a neuron spike on its own and thus release neurotransmitter. However, it can shift the timing of spikes caused by its “natural” activity”, and thus change those activity patterns.
(My group looks at this in animal and computational models, where we can measure this directly).