Effects of working memory training on oscillatory activity in patients with mild cognitive impairment and age-matched elderly controls
Corinna
Haenschel1, 2*,
D.
Prvulovic1,
A.
Etzold1,
N.
Tunc1,
H.
Brühl1,
K.
Muth1,
J.
Pantel1,
K.
Maurer1,
E.
Rodriguez2, 3 and
D.
E.
Linden4
-
1
Johann Wolfgang Goethe Univ, Germany
-
2
Max-Planck-Institut for Brain Research, Germany
-
3
Universidad Catolica de Chile, Chile
-
4
School of Psychology,Bangor University, United Kingdom
Background: The stages of cognitive impairment that may lie between normal ageing and early dementia are of great interest if we want to develop strategies for preventing dementia. Recently, the construct of mild cognitive impairment (MCI) has been proposed to designate an early state of cognitive impairment that deviates from the age norm. We conducted a cognitive training study with an MCI group and healthy elderly controls in order to investigate how far mechanisms of neural plasticity are preserved in these groups. Our particular interest was whether and to what degree cognitive training might lead to a change in task-related brain activation patterns. We expected a relationship between performance improvements and changes in ERPs and oscillatory activity.
Methods: 20 MCI patients (mean age: 61) and 20 healthy controls (mean age: 63) took part in a training using a delayed discrimination task over a period of 4 weeks. Before and following the training we recorded EEG. We varied WM load by presenting one or three visual objects that were shown sequentially for 1 second each. Following a delay of 8 seconds subjects had to compare the memorized objects to a probe, which matched in fifty percent of the trials. 64-channel EEG was acquired at a 500Hz sampling rate. Encoding, maintenance and the retrieval periods were analyzed for both ERPs and oscillatory low (theta and alpha) and high-frequency beta and gamma oscillations using a sliding window FFT.
Results: Training reduced the number of errors in both groups, but had no effect on reaction time. Overall, there was no difference between groups. However, we found a relationship between performance increase and changes in ERP and oscillatory activity. Furthermore, whereas training resulted in an increase in early visual activity during encoding and retrieval (P1/N1 complex and evoked gamma activity), it resulted in a decrease in oscillatory activity during maintenance.
Conclusion: These different effects suggest that training has differential effects on perceptual and higher order cognitive functions. An increase in early visual ERP and evoked oscillatory activity during encoding may indicate stronger perceptual integration, whereas reductions in induced oscillatory activity may indicate a sharpening of neural activity across the WM network. The results suggest WM training has beneficial effects in both groups. Furthermore, it indicates that patients with MCI show at least partially preserved mechanisms of training-related neural plasticity.
Conference:
10th International Conference on Cognitive Neuroscience, Bodrum, Türkiye, 1 Sep - 5 Sep, 2008.
Presentation Type:
Oral Presentation
Topic:
Symposium 12: Gamma-band responses in the brain: A general
Mechanism subserving cortical information processing?
Citation:
Haenschel
C,
Prvulovic
D,
Etzold
A,
Tunc
N,
Brühl
H,
Muth
K,
Pantel
J,
Maurer
K,
Rodriguez
E and
Linden
DE
(2008). Effects of working memory training on oscillatory activity in patients with mild cognitive impairment and age-matched elderly controls.
Conference Abstract:
10th International Conference on Cognitive Neuroscience.
doi: 10.3389/conf.neuro.09.2009.01.054
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Received:
28 Nov 2008;
Published Online:
28 Nov 2008.
*
Correspondence:
Corinna Haenschel, Johann Wolfgang Goethe Univ, Frankfurt, Germany, Germany.haenschel@npih-frankfurt.mpg.de