Abstract
Working memory (WM), a central component of general cognition, plays an essential role in human beings' daily lives. WM impairments often occur in psychiatric, neurodegenerative, and neurodevelopmental disorders, mainly presenting as loss of high-load WM. In previous research, electroacupuncture (EA) has been shown to be an effective treatment for cognitive impairments. Frequency parameters are an important factor in therapeutic results, but the optimal frequency parameters of EA have not yet been identified. In this study, we chose theta-EA (θ-EA; 6 Hz) and gamma-EA (γ-EA; 40 Hz), corresponding to the transcranial alternating-current stimulation (tACS) frequency parameters at the Baihui (DU20) and Shenting (DU24) acupoints, in order to compare the effects of different EA frequencies on WM. We evaluated WM performance using visual 1-back, 2-back, and 3-back WM tasks involving digits. Each participant (N = 30) attended three different sessions in accordance with a within-subject crossover design. We performed θ-EA, γ-EA, and sham-EA in a counterbalanced order, conducting the WM task both before and after intervention. The results showed that d-prime (d′) under all three stimulation conditions had no significance in the 1-back and 2-back tasks. However, in the 3-back task, there was a significant improvement in d′ after intervention compared to d′ before intervention under θ-EA (F [1, 29] = 22.64; P < 0.001), while we saw no significant difference in the γ-EA and sham-EA groups. Reaction times for hits (RT-hit) under all three stimulation conditions showed decreasing trends in 1-, 2-, and 3-back tasks but without statistically significant differences. These findings suggest that the application of θ-EA might facilitate high-load WM performance.
Highlights
Working memory (WM) can be defined as the ability to maintain and manipulate new and stored memory information for a short period of time [1]
Another study evaluated the effect of EA delivered to the Baihui (DU20) and Shenting (DU24) acupoints at a frequency of 80 Hz on vascular cognitive impairment with no dementia (VCIND); the results showed a clear improvement in patients’ cognitive ability and quality of life [36]
We investigated changes in WM performance after c-EA and θ-EA using n-back tasks, with a sham-EA group being used as the control group
Summary
Working memory (WM) can be defined as the ability to maintain and manipulate new and stored memory information for a short period of time [1]. Working-memory load (WM load) is the amount of information that must be held in the mind at any given time [7]. WM is especially impaired when memory load is high [5, 8,9,10]. E n-back task, a typical WM paradigm, is widely used to manipulate WM processing load. Older adults generally exhibit poor WM performance in the high-load n-back task [11]. Several studies have found that people with WM impairment show abnormal cortical electrical activity [12, 13]
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