Page 357 - merged

S087-1

Dynamical Analysis of Brain Activity: A New Research Dimension

Albert Yang

Department of Psychiatry, Taipei Veterans General Hospital, Taiwan

Background/Objective: A defining but elusive feature of the human brain is its astonishing
complexity. This complexity arises from the interaction of numerous neuronal circuits that operate
over a wide range of temporal and spatial scales, enabling the brain to adapt to the constantly
changing environment and to perform various amazing mental functions. In mentally ill patients,
such adaptability is often impaired, leading to either ordered or random patterns of behavior.
Quantification and classification of these abnormal human behaviors exhibited during mental illness
is one of the major challenges of contemporary psychiatric medicine.

Method: In the past few decades, attempts have been made to apply concepts adopted from
complexity science to better understand complex human behavior. We and others have introduced
applications of methods derived from complexity science for examining aging and mental illness.
The complexity analysis aims to quantify the dynamical changes of spontaneous brain activity that is
typically measures via electroencephalogram, magnetic-electroencephalogram, or functional
magnetic resonance imaging.

Result: We found that aging is associated with reduced complexity of resting-state brain activity (1).
We also found that such reduced brain complexity is associated with genotype, such as
Apolipoprotein E. Furthermore, we found that schizophrenic patients exhibits two types of reduced
brain complexity toward regularity or randomness, which are associated with positive and negative
symptoms, respectively (2).

Conclusion: We propose that the brain pathology associated with aging and mental illness can be
studied under a general framework by quantifying the order and randomness of dynamic
macroscopic human behavior and microscopic neuronal activity. Additionally, substantial effort is
required to identify the link between macroscopic behaviors and microscopic changes in the neuronal
dynamics within the brain.

Reference: Yang AC , Huang CC, Yeh HL, Liu ME, Hong CJ, Tu PC, Chen JF, Huang NE, Peng CK,
Lin CP*, Tsai SJ*. Complexity of spontaneous BOLD activity in default mode network is correlated
to cognitive Function in normal male elderly: a multiscale entropy analysis. N
Yang AC*, Hong CJ, Liou YJ, Huang KL, Huang CC, Liu ME, Lo MT, Huang NE, Peng CK, Lin CP,
Tsai SJ. Decreased resting-state brain activity complexity in schizophrenia characterized by both
increased regularity and randomness. Human Brain Mapping doi: 10.1002/hbm.22763 (2015).