Project Motivations

Working memory deficits are linked to several neurodegenerative disorders including Alzheimer’s, Parkinson's, attention-deficit/hyperactivity disorder (ADHD), and dementia. As diagnostic technologies advance, there is a need for early-onset therapy and prevention. The current standard of care is a pharmaceutical approach. With that approach, adverse effects and complications can arise from unintended interactions with ongoing bodily processes. Additionally, these pharmaceuticals are rarely personalized to the patient.

In recent years, the emergence of noninvasive brain stimulation (NIBS) has gained momentum as it directly targets the area of interest through cortical modulation. Specifically, transcranial alternating current stimulation (tACS) is the process of applying alternating electrical current at a set frequency to interact with the brain’s natural cortical oscillations. tACS relies on the electrical nature of biological circuits in the body. Underlying cortical oscillations of neurons can be manipulated in a process known as entrainment. This process is similar to the mechanism involved in binaural beats in which the cortical oscillations are altered via the input of two different sine waves in the form of sound. In addition, the electrical impedance of the neurons can be altered through the application of current to the scalp. Unlike transcranial direct current stimulation (tDCS), tACS applies sinusoidal alternating current to the brain, closely mimicking the natural oscillations, whereas tDCS applies a constant current. Research has suggested that tACS can help improve symptoms of Alzheimers, Parkinsons, ADHD, and dementia through entrainment of various neuronal groups and improving the working memory of these individuals. Not only can tACS therapy help those with neurological disorders, but also individuals who are simply looking to increase their working memory. This is done by intensifying the gamma waves in active regions of the brain and suppressing alpha waves in inactive regions.

However, most tACS devices used today are feedforward systems, meaning that a preprogrammed waveform is generated by the device and sent to the brain. Once the signal has been applied, there is no way to adjust it to better adapt to the patient to maximize results. This project aims to create a closed-loop device that will utilize EEG feedback to fine-tune the tACS application to better suit each person’s brain and correct for individual brain response.

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