By implanting neural sensor arrays into the brains of monkeys, scientists in Malibu, Montreal, and New York have begun to discover why tDCS electrical brain stimulation seems to boost learning. By measuring the brain’s response to tDCS while in the process of learning, researchers found that targeted electrical stimulation on the scalp facilitates high frequency brain wave coherence between distant brain regions. Brain wave synchrony at these frequencies seems to raise learning efficiencies and speeds.
First, scientists at McGill took macaques monkeys and implanted sensor arrays inside their brains. While other studies have done similar experiments monitoring the brain with an EEG machine, here scientists could measure the firing of neurons in vivo (from the inside), using intracranial sensing.
… The non-stimulated monkeys went through 22 trials before the association was fully formed. Stimulated monkeys took only 12 trials. This was about a 40% improvement in learning speed.
The tDCS cut the average number of trials to learn the assigned task (visual foraging for food) almost in half. And the scientists also learned the best moment in time to engage the electrical stimulation for the specific task, to maximise learning efficiency.
“The improved long-range connectivity between brain areas in the high frequency bands and reduced connectivity in the low frequency bands were the determining factors in our study that could explain the learning improvements with tDCS of the prefrontal cortex,” Pilly said. “Just because neurons can be more brisk in their firing may not lead to changes in performance. Boosting memory function likely requires better coordination of task-relevant information across the cortex.” __ HRL Laboratories h/t Brian Wang
Published study abstract in Current Biology
Brain wave synchrony between distant brain areas at higher frequencies is thought to be the primary way that different aspects of complex “thought objects” are bound together. This concept was explored in depth in the book “Rhythms of the Brain” by Gyorgy Buszaki.
2 hour seminar on noninvasive brain stimulation from Center for Consciousness Studies:
NIH lecture series on Multimodal Brain Stimulation:
We are in the early stages for this type of research, using electromagnetic stimulation to enhance normal human potential. Up until now, most research using these modalities (TMS, tDCS etc) looked specifically at the potential for mitigating disease states such as Parkinson’s, depression, schizophrenia, Alzheimers, and other diseases related to brain pathology.
Given that the tDCS learning research above was sponsored by the US DARPA, it is likely that it will be pursued as long as it shows positive potential.