Measurements of brain activity complexity for varying mental loads

Mukeshwar Dhamala, Giuseppe Pagnoni, Kurt Wiesenfeld, and Gregory S. Berns
Phys. Rev. E 65, 041917 – Published 4 April 2002
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Abstract

Using functional magnetic resonance imaging, we investigate the variation in dynamical complexity of human brain activity for different mental loads. Our experiments measured the activity of ten subjects under three experimental conditions: a rest condition, a periodic task of finger opposition, and a task of finger opposition alternated with mathematical serial calculation. We used the correlation dimension to gauge the spatiotemporal complexity of brain activity. The experiments show a direct relationship between this complexity and the difficulty of the task. A natural interpretation is that higher levels of mental load recruit a larger number of independent neural processes that contribute to complex brain dynamics. These results suggest the possibility that the relative change in correlation dimension can be a useful global measure of brain dynamics, e.g., in determining the levels of mental activity, even if little is known about the underlying neurological processes.

  • Received 6 June 2001

DOI:https://doi.org/10.1103/PhysRevE.65.041917

©2002 American Physical Society

Authors & Affiliations

Mukeshwar Dhamala1,2, Giuseppe Pagnoni2, Kurt Wiesenfeld1, and Gregory S. Berns2,3

  • 1School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
  • 2Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia 30322
  • 3Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332

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Vol. 65, Iss. 4 — April 2002

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