Effects of HD-tDCS During Slow-wave Sleep on Associative Memory

Effects of High-definition Transcranial Direct Current Stimulation During Slow-wave Sleep on Associative Memory

To evaluate the effects of afternoon naps and high-definition transcranial direct current stimulation (HD-tDCS) over the left dorsolateral prefrontal cortex (DLPFC) in associative memory (AM)

Healthy adults will be randomized into three groups: a sleep with active stimulation (Sleep-A) group will receive active anode HD-tDCS during slow-wave sleep (SWS) of non-rapid eye movement sleep (NREM) at afternoon nap, a sleep with sham stimulation (Sleep-S) group will receive afternoon nap with sham stimulation, and wake with active stimulation (Wake-A) group will receive active anode HD-tDCS during wakefulness. An anode stimulation electrode will be placed in F3 (10/20 system) which intend to target the left DLPFC, and four cathodes will be placed at FCz, AFz, F7, and C5 (10/20 system). The face-word AM task and other multidimensional neuropsychological tasks will be performed before and after afternoon napping.

Inclusion Criteria:

• aged 18-30 years
• healthy adults

Exclusion Criteria:

• with pacemakers, skull cavities or cracks；
• intolerance of high-definition transcranial direct current stimulation (HD-tDCS) adverse reactions；
• left-handed；
• diagnosed with severe mental disorders, or involved in other experiments.