Unsupervised fuzzy clustering analysis supports behavioral cutoff criteria in an animal model of posttraumatic stress disorder.
BACKGROUND
Unsupervised fuzzy clustering (UFC) analysis is a mathematical technique that groups together objects in the multidimensional feature space according to a specified similarity measurement, thereby yielding clusters of similar data points that can be represented by a set of prototypes or centroids.


METHODS
Since clinical studies of mental disorders distinguish between affected and unaffected individuals, we designed an inclusion/exclusion criteria (cutoff behavioral criteria [CBC]) approach for animal behavioral studies. The effect of classifying the study population into clearly affected versus clearly unaffected individuals according to behaviors on two behavioral paradigms was statistically significant.


RESULTS
Here the raw data from previous studies were subjected to UFC algorithms as a means of objectively testing the validity of the concept of the CBC for our experimental model. The first UFC algorithm yielded two clearly discrete clusters, found to consist almost exclusively of the exposed animals in the one and unexposed animals in the other. The second algorithm yielded three clusters corresponding to animals designated as clearly affected, partially affected, and clearly unaffected. The algorithm for physiological data in addition to behavioral data failed to elicit discrete clusters.


CONCLUSIONS
The UFC analysis yielded data that support the conceptual contention of the CBC and lends additional validity to our previous behavioral studies.
Cohen
Hagit
H
Ministry of Health Mental Health Center, Anxiety and Stress Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84170, Israel. hagitc@bgu.ac.il
Zohar
Joseph
J
Matar
Michael A
MA
Kaplan
Zeev
Z
Geva
Amir B
AB
D000161:Acoustic Stimulation / Q000379:methods; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D016000:Cluster Analysis; D004195:Disease Models, Animal; D017143:Fuzzy Logic; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D013216:Reflex, Startle / Q000502:physiology; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology*; D013997:Time Factors