Working memory revived in older adults by synchronizing rhythmic brain circuits

Reinhart, Robert MG, and John A Nguyen. 2019. 'Working memory revived in older adults by synchronizing rhythmic brain circuits', Nature neuroscience, 22: 820-27.
 
Summary:        Theta oscillations couple to gamma oscillations to support working memory. However, in healthy aging these oscillations become uncoupled resulting in reduced working memory capacity. Reinhart and Nguyen delivered high-definition tACS to both prefrontal and auditory cortex in synchrony and found that theta-gamma coupling was restored in older participants. The older participants showed performance level similar to the younger participants. Stimulation was only effective when synchronizing frontal and auditory, but was not effective to either region individually.
 
Pros:

• Impressive behavioral findings to restore cognition in older participants
• Valuable control stimulation demonstrating the effects require synchronous stimulation of both sites
• Evidence of target engagement

 
Open questions:

• Are the effects of stimulation long lasting?
• Does stimulation require high-definition tACS or would more traditional (larger) stimulation electrodes be sufficient?
• Does stimulation enhance connectivity between the targeted regions?

 
Contributed by: Justin Riddle, PhD