HD tACS to Synchronize Medial Frontal Cortex & Lateral Prefrontal Cortex Leads to Improved Executive Function

[Update 4/19] Reinhart Lab has a new paper out that is going to attract a lot of attention. Using HD-tACS, they were able to improve Working Memory in older adults (compared to younger adults). This article nicely summarizes the experiment: Brainwave Synchronization Reverses Age-related Decline in Working Memory …HD-tACS boosted interactions between theta & gamma rhythms in left temporal cortex & synchronization of theta brainwaves between left temporal cortex and prefrontal cortex. Paper: Working memory revived in older adults by synchronizing rhythmic brain circuits.


You may have noticed that I’ve not been posting as much to the blog lately. The blog is already so full of useful content for anyone looking into tDCS that I’m inclined to only post significant information that would move our current understanding of tDCS and neurostimulation forward. This article/paper describing a new technique using ‘HD tACS’ to synchronize (brainwaves) parts of the brain definitely looks intriguing and has implications for anyone paying attention to DIY neurostimulation. Very early, but very interesting.

Prof Rob Reinhart. Photo by Cydney Scott for Boston University Photography

Full story:  “Turbo Charge” for Your Brain? by By Barbara Moran

“These (medial frontal cortex & lateral prefrontal cortex) are maybe the two most fundamental brain areas involved with executive function and self-control,” says Reinhart, who used a new technique called high-definition transcranial alternating current stimulation (HD-tACS) to stimulate these two regions with electrodes placed on a participant’s scalp. Using this new technology, he found that improving the synchronization of brain waves, or oscillations, between these two regions enhanced their communication with each other, allowing participants to perform better on laboratory tasks related to learning and self-control. Conversely, de-synchronizing or disrupting the timing of the brain waves in these regions impaired participants’ ability to learn and control their behavior, an effect that Reinhart could quickly fix by changing how he delivered the electrical stimulation. The work, published October 9, 2017, in the journal Proceedings of the National Academy of Sciences (PNAS), suggests that electrical stimulation can quickly—and reversibly—increase or decrease executive function in healthy people and change their behavior.

Here’s the paper (paywall): Disruption and rescue of interareal theta phase coupling and adaptive behavior. The supplemental pdf. describes the equipment used in the experiment.
High definition transcranial alternating current stimulation ( HD- tACS ). The alternating current stimulation was administered noninvasively using an MxN9-3 channel high definition transcranial electrical current stimulator from Soterix Medical (New York, NY). Eight sintered Ag/AgCl electrodes were attached to high-definition plastic holders, filled with conductive gel, and embedded in the Biosemi EEG cap. HD-tACS electrode placement was guided by current-flow modeling using HD- Explore and HD-Targets (Soterix Medical), with the goal of targeting the MFC and lPFC to facilitate the synchronization of neural activity between these regions (the in phase protocol ) or disrupt the signals being conveyed between the MFC and lPFC (the antiphase protocol ).

Listen to Bob McDonald discuss HD tACS with Prof Rob Reinhart on the always interesting Quirks and Quarks.

Adam Gazzaley – Consciousness & Neuroscience | After-On – Rob Reid

We’ve met Adam Gazzaley elsewhere on the blog, but probably because he and Rob Reid have a friendship spanning years, this is a very friendly and thorough discussion of all Adam is up to. Reid has a new book (fiction, sci-fi) called After On, and Gazzaley was called on to provide insights into a few of the book’s key concepts related to consciousness and neuroscience.
There has been a lot of talk in the literature lately about tACS as it applies to cognitive enhancement and this is explored in the conversation. If I got this right… there is a distinct pattern of ‘Midline Frontal Theta’ frequency, at around 6Hz (as measured by EEG) associated with ‘focus’ (as measured by fMRI) in the Pre Frontal Cortex. This begs the question as to whether focus could be generated by using tACS to ‘entrain’ the PFC (as in… induce 6Hz Theta in the PFC using tACS). Again I will remind the reader that I am not a scientist!
Gazzaley also brings us up to speed on the clinical trial for FDA clearance of EVO, his video game/therapeutic that Akili has developed for kids with ADHD.
The episode is embedded here, but swing over to https://after-on.com/episodes/002 to read the show notes and to learn more about Rob Reid. He has a number of fascinating interviews with other guests in his podcast and brings a lot to the table himself considering a long career both as a technologist, investor and author.

Video Games for Neuro-Cognitive Optimization

Video Games for Neuro-Cognitive Optimization
Neuroscape Lab at UCSF Publications
Enhancement of multitasking performance and neural oscillations by tACS
Nature cover story: Video gaming enhances cognitive skills that decline with age. Game Changer (pdf)