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Quadratic dose-response relationship between caffeine (1,3,7-trimethylxanthine) and EEG correlation dimension


Watters, PA and Martin, F and Schreter, ZG, Quadratic dose-response relationship between caffeine (1,3,7-trimethylxanthine) and EEG correlation dimension, Psychopharmacology, 136, (3) pp. 264-271. ISSN 0033-3158 (1998) [Refereed Article]

DOI: doi:10.1007/s002130050565


Many studies have failed to determine a systematic dose-response relationship across different cognitive tasks between caffeine and EEG power spectra. However, a nonlinear approach to EEG analysis, which reconstructs a multi-dimensional state space from each electrode recording, can be used to-compute the number of active degrees of freedom in the signal (the correlation dimension, D2), and can be interpreted as a measure of signal complexity. This study attempted to determine a consistent dose-response relationship between caffeine and EEG D2, across six oral caffeine doses (100-600 mg), with each subject acting as their own control, to create a probabilistic bias against finding any consistent linear or nonlinear dose-response relationship across different cognitive tasks. The experiment (n = 10) was conducted with three within-subjects explanatory variables, 2 (experimental, placebo) x 8 (caffeine level) x 4 (type of cognitive task performed), with EEG D2 as the response variable, measured from Fz, F3, F4 and Cz. A significant three-way interaction was found [F(21,245.3) = 3.65, P = 0.001]. Regression analyses revealed a linear trend for the, response variable across trials for the placebo,condition (average R2 = 0.54, whereas linear+quadratic trends explained an average 30% of the variance for the experimental condition, compared to 0.01% for the linear fit, indicating a robust quadratic dose-response relationship between caffeine and EEG D2. Three conditions had positive quadratic co-efficients, and one condition had a negative quadratic co-efficient. These results are discussed in terms of the implications for brain dynamics, and with respect to recent criticisms of the computation of D2 from EEG.

Item Details

Item Type:Refereed Article
Research Division:Psychology
Research Group:Biological psychology
Research Field:Behavioural neuroscience
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Watters, PA (Mr Paul Andrew Watters)
UTAS Author:Martin, F (Associate Professor Frances Martin)
UTAS Author:Schreter, ZG (Dr Schreter)
ID Code:14828
Year Published:1998
Web of Science® Times Cited:7
Deposited By:Psychology
Deposited On:1998-08-01
Last Modified:2011-08-09

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