Alcohol 26 (2002) 145–153
0741-8329/02/$ – see front matter © 2002 Elsevier Science Inc. All rights reserved.
PII:
S0741-8329(01)00204-X
Alcohol-induced alterations in ERD/ERS during an auditory memory task
Christina M. Krause
a,b,c
*, Anu Aromäki
d
, Lauri Sillanmäki
b,e
, Teresia Åström
b,c,d
,
Katarina Alanko
b,d
, Eija Salonen
b,c
, Olli Peltola
f
a
Laboratory of Computational Engineering, PB 9400, Helsinki University of Technology, 02015 Espoo, Finland
b
Centre for Cognitive Neuroscience, University of Turku, 20014 Turku, Finland
c
Department of Psychology, University of Turku, 20014 Turku, Finland
d
Department of Psychology, Åbo Akademi University, 20500 Turku, Finland
e
Department of Statistics, University of Turku, 20014 Turku, Finland
f
Central Laboratory, University Central Hospital of Turku, 20014 Turku, Finland
Received 2 October 2000; received in revised form 22 November 2001; accepted 28 November 2001
Abstract
The purpose of the present study was to examine the effects of alcohol on EEG event-related desynchronization (ERD) and event-
related synchronization (ERS) of the 4–6, 6–8, 8–10, and 10–12 Hz frequency bands during an auditory memory task. Twenty subjects per-
formed an auditory memory task during which the EEG was recorded. Half the subjects performed the task without the administration of
alcohol and half under the influence of alcohol (
ف
0.7 g/l). The administration of alcohol itself did not alter the ERD/ERS responses
.
However, when the effects of alcohol were studied as a function of time and task (encoding vs. retrieval), we observed significant effects
in the 4–6, 6–8, and 8–10 Hz frequency bands such that the administration of alcohol decreased the early-appearing ERS responses during
auditory encoding and increased the later-appearing ERD responses during retrieval. Our results indicate that alcohol has disorganizing
effects on brain electric oscillatory systems in the theta and lower alpha frequency range during cognitive processing. © 2002 Elsevier
Science Inc. All rights reserved.
Keywords:
EEG; Alpha; Theta; Cognition, Alcohol; Human being
1. Introduction
Different frequencies within the EEG have traditionally
been categorized in frequency bands, such as theta (4–8 Hz),
alpha (8–12 Hz), beta (
ف
14–30 Hz), and gamma (
ف
40 Hz).
During stimulation, the simultaneously recorded responses of
different EEG frequency bands differ from one another (Kli-
mesch, 1997; Klimesch et al., 1997b; Pfurtscheller & Neuper,
1992) and correspond to different cognitive or mental pro-
cesses or states or both (Dumont et al., 1999; Klimesch, 1996;
Klimesch et al., 1994). Different neural generators have been
proposed to take part in the propagation of different EEG fre-
quencies (Fernandez et al., 1998). For example, hippocampal
neural activity has been associated with oscillations within
the theta frequency band (
ف
4–8 Hz) (Burgess & Gruzelier,
1997), whereas the alpha rhythm (
ف
8–12 Hz) has been
claimed to be generated mainly by corticocortical and
thalamocortical neural circuits (Klimesch, 1996).
The role of brain electric oscillations in association with
human information processing has been intensively dis-
cussed (Basar et al., 1997, 1999a, 1999b, 2000; Klimesch,
1997, 1999; Klimesch et al., 1997a; Tesche & Karhu, 2000),
and it has been argued that distributed theta, alpha, and
gamma oscillatory systems might act as resonant communi-
cation networks through a large population of neurons with
functional relations to memory and integrative functions
(Basar et al., 1999b; Tesche & Karhu, 2000). For example,
episodic memory processes have been associated with oscil-
lations within the 4–8 Hz EEG theta frequency range (Dop-
pelmayr et al., 1998b; Klimesch et al., 1994), 8–10 Hz alpha
activity has been observed to be modulated as a function of
attentional demands (Klimesch, 1997; Klimesch et al.,
1998), and 10–12 Hz alpha activity has been reported to be
modulated by stimulus-related aspects or semantic memory
processes or both (Klimesch, 1996; Klimesch et al., 1994,
1997a, 1997b).
One way to assess the stimulus-related responses of dif-
ferent EEG frequency bands is the so-called event-related
desynchronization (ERD) and event-related synchronization
(ERS) analysis of the EEG (Aranibar & Pfurtscheller, 1978;
* Corresponding author. Tel.: INTL
ϩ
358-9-4515736, INTL
ϩ
358-
500-699972; fax: INTL
ϩ
358-9-451 4830.
E-mail address:
krause@lce.hut.fi (C.M. Krause).
Editor: S. Borg