Effects of noninvasive brain stimulation during slow wave sleep on visual memory in younger and older adults S. Paßmann, N. Külzow, A. Flöel Department of Neurology, Charité-Universitätsmedizin Berlin NeuroCure Cluster of Excellence, Neurocure Clinical Research Center, Charite-Universitätsmedizin, Berlin contact:
[email protected]
Introduction Previously the application of a weak transcranial slow oscillatory electric current (tSOS) during non-rapid eye movement sleep (NonREM)
within the frequency range of slow wave sleep (SWS; 0.7-0.8 Hz) enhanced sleep-associated memory consolidation in a word-pair associative task in healthy young adults (1). However, how these findings relate to other hippocampus-dependent declarative memory tasks, e.g. visual tasks, have not been studied so far. Further, since memory functions as well as sleep architecture (2) are strongly age dependent, it also remains unclear if similar effects occur in healthy older adults.
Aim Examining whether the application of tSOS during SWS promotes sleep-dependent memory in a visual task in younger and older healthy adults.
Material / Subjects: 16 healthy younger Methods
Visual Recognition Task • Encoding: 38 neutral pictures of different categories e.g., objects, plants, scenes; data base: IAPS, MULTIMOST(4) presented in one of four quadrants (Fig. 2)
(mean 24.81 ± 4.88 , 7 male) and educationmatched older adults (mean 63.69 ± 6.23 , 8 male)
Design: cross over with tSOS or SHAM stimulation (counterbalanced, experimental nights were separated by at least 2-3 weeks)
• Recall (immediate and delayed): OLD/NEW recognition task: 38 old intermixed with 38 new neutral (similar to old) pictures centered on the screen - if a picture deemed as “OLD” – a “WHERE“ response was required (indicating quadrant of picture during encoding)
Stimulation: • location: bifrontal • duration: 5 x 5min-blocks of oscillatory stimulation, 1min artifact- and stimulation-free intervals in between • frequency: 0.75Hz, onset: 260μA, max. current density: 0,522mA/cm2 anodes
Fig 1. Schematic description of procedure
Fig 2. Encoding and recall of visual spatial task Garten - Beet
500 ms
Wo wurde das Bild gezeigt?
cathodes
2000 ms
regular nocturnal sleep
Garten - Beet
Garten - Beet
Proband: SW S-J-011-Exp1N_sp.vhdr
W REM S1
2000 ms
Garten - Beet
S2
Garten - Beet
1000 -1500 ms
S3 S4
2000 ms
neuropsych. assessment
encoding & M immed. recall
adaptation night
Time
time
9.30-10.30 pm
22:00
23:00
00:00
11.00 pm
tSOS/SHAM
01:00
12.00 am
02:00
03:00
7.30 am
delayed recall 04:00
3000 ms
+ 05:00
06:00
+
07:00
1000 ms
7.50–8.15 am
1000 ms
encoding trial
4 minutes after start NREM2
immediate-/ delayed recall
Results Visual Recognition Task:
• younger adults performed better after STIM compared to SHAM night (T=2.21, p= .043) • older adults showed reserved pattern (T= -1.73, p= .104;
performance on visual task
stim sham
stim sham
30
3
Fig. 3).
significant
*
difference from learning
no
difference from learning
2
Location (WHERE) Task: • No significant effects (young: T
