[Abstract Title]. - Society for Neuroscience

1 Dept Exp Neurophysiol., VU Univ. Amsterdam, Amsterdam, Netherlands; 2 Ctr. for
Neurogenomics and Cognitive Res. (CNCR), Amsterdam, Netherlands; 3 Inst. of Biophysics and
Biomed. Engin., Lisbon, Portugal; 4 Dept Clin. Neurophysiol., 5 Dept Neurol., VU Univ. Med.
Ctr., Amsterdam, Netherlands; 6 Dept. of Physics and Med. Technol., Amsterdam, Netherlands;
7 MEG Ctr., Amsterdam, Netherlands; 8 Alzheimer Ctr., Amsterdam, Netherlands
Abstract: Sustained oscillatory activity on time scales of seconds is commonly observed for
different frequency bands in the retention interval of a working-memory task [1,2]. Interestingly,
during resting-state conditions, which are known to be associated with prominent retrieval and
manipulation of information in working memory, ongoing oscillations also exhibit amplitude
modulations on multiple time scales, as indicated by long-range temporal correlations (LRTC)
up to tens of seconds [3,4]. We reasoned that correlations in oscillations over time might be
important for memory and could therefore be abnormal in Alzheimer's disease (AD). To test this
hypothesis, we measured magnetoencephalography (MEG) during eyes-closed rest in 19 patients
diagnosed with early-stage AD and 16 age-matched control subjects and characterized temporal
correlations in ongoing oscillations using detrended fluctuation analysis and a novel "avalanche
analysis" that quantifies the life- and waiting-time probability distributions of oscillation bursts
[5]. We found that Alzheimer‟s patients had markedly weaker long-range temporal correlations
in the alpha band (6-13 Hz) over temporo-parietal regions on time scales of 1-25 seconds. On
shorter time scales (< 1 second), abnormal dynamics of alpha oscillations in AD patients were
expressed as a strongly reduced probability for the occurrence of oscillation bursts with long lifetimes
or for long waiting-times between bursts in the temporo-parietal regions. These regions
have been associated with mnemonic functions in healthy subjects and show metabolic and
structural deficits in AD, suggesting that the tendency for ongoing alpha oscillations to carry a
memory of their own amplitude dynamics is important for cognition.
References
[1] Raghavachari et al. (2001) J Neurosci 21:3175-3183.
[2] Jensen et al. (2002) Cereb Cortex 12:877-882.
[3] Linkenkaer-Hansen et al. (2001) J Neurosci 21:1370-1377.
[4] Linkenkaer-Hansen et al. (2007) J Neurosci 27:13882-13889.
[5] Poil, van Ooyen, Linkenkaer-Hansen (2008) Human Brain Mapping (10.1002/hbm.20590).
Disclosures: K. Linkenkaer-Hansen , None; T. Montez, None; S. Poil, None; B.F. Jones,
None; I. Manshanden, None; J.P.A. Verbunt, None; B.W. van Dijk, None; A.B. Brussaard,
None; A. van Ooyen, None; C.J. Stam, None; P. Scheltens, None.
Poster
246. Alzheimer's Imaging and Biomarkers II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 246.3/P7