High-density neuromodulation using network-based transcranial alternating current stimulation

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We are requesting funds for the Geodesic Transcranial Electrical Neuromodulation (GTEN) hardware and software add-on for our high-density electroencephalography (dEEG) system already in place in our UBC Brain Dynamics Lab (Dr. Todd Woodward, principal investigator; Dr. Christine Tipper, co-investigator and scientific director). dEEG has allowed us to measure the networks of frequencies of oscillation that underlie cognitive tasks, but we must now test our observations by feeding the patterns of network activity back, using neuromodulation through transcranial alternating current stimulation (tACS) to show that the hypothesized pattern of neuromodulation indeed affects behavior on those tasks. The GTEN add-on offers three critical advantages over typical neuromodulation tACS systems: 1) 256 electrodes are used to deliver oscillatory current in flexible patterns that can precisely target stimulation of specific brain areas, rather than two large sponge electrodes that distribute stimulation in an anatomically untargeted manner; 2) the same array of electrodes that delivers current also records EEG brain activity to confirm that the neurmodulation exerted the expected effects, and 3) GTEN current delivery is optimized with a high performance computational physics simulation of the tissue conductivity of each person’s unique head and brain morphology. The power of GTEN to document changes in behaviour in response to neuromodulation is evidenced by the availability of powerful control conditions. Specifically, the experimental condition of optimized targeting of tACS stimulation of previously recorded oscillatory network configurations can be compared to the control condition of suboptimal spatial distribution of stimulation, suboptimal stimulation frequencies of oscillation, and/or suboptimal temporal targeting of stimulation. With this experimental setup, behavioural changes in response to neuromodulation will be powerfully demonstrated. The dEEG/GTEN system would be the first in Canada. A delay in procurement will jeopardize the opportunity for our current graduate students to be trained in the methodology, and delay advancement in cognition and cognitive neuroscience.