Table 1.

Mean ± SEM number of correctly recalled word pairs on the PAL task and speed and accuracy of performance on the MT task before (Learning) and after (Recall) the retention interval

Learning (mean ± SEM) Recall (mean ± SEM) Retention (mean ± SEM) Significance (p)
PAL
Sleep
tDCS 33.0 ± 1.4 35.7 ± 1.4 2.7 ± 0.6 p < 0.005
Placebo 33.6 ± 1.5 34.5 ± 1.5 0.9 ± 0.8
Wake
tDCS 36.2 ± 1.5 36.3 ± 1.2 0.0 ± 1.0 p > 0.8
Placebo 34.0 ± 1.4 33.7 ± 1.4 −0.3 ± 0.5
MT draw time (in milliseconds)
Sleep
tDCS 72.63 ± 9.57 55.77 ± 6.06 −16.86 ± 4.58 p > 0.5
Placebo 72.00 ± 7.88 58.68 ± 5.02 −13.32 ± 3.67
Wake
tDCS 60.00 ± 6.72 52.50 ± 6.75 −7.51 ± 5.80 p > 0.3
Placebo 63.33 ± 14.21 46.81 ± 9.60 −16.52 ± 5.76
MT error count
Sleep
tDCS 7.1 ± 1.4 5.4 ± 1.3 −1.8 ± 0.6 p > 0.8
Placebo 6.6 ± 1.6 4.5 ± 1.4 −1.9 ± 0.7
Wake
tDCS 14.6 ± 3.5 8.7 ± 1.5 −5.9 ± 1.7 p > 0.5
Placebo 12.7 ± 3.1 8.8 ± 1.2 −3.9 ± 2.3
  • Retention is defined by the difference in retrieval performance before and after the retention interval. The retention interval was filled with Sleep or wakefulness (Wake), during which either tDCS or placebo stimulation was applied. The right column indicates significant differences in retention, compared with the respective placebo condition. Corresponding performances during learning and recall did not differ significantly (see Results for details).