Indic, PremanandaSalvatore, PaolaMaggini, CarloGhidini, StefanoFerraro, GabriellaBaldessarini, RossMurray, Greg2011-12-232011Indic, Premananda, Paola Salvatore, Carlo Maggini, Stefano Ghidini, Gabriella Ferraro, Ross J. Baldessarini, and Greg Murray. 2011. Scaling behavior of human locomotor activity amplitude: association with bipolar disorder. PLoS ONE 6(5): e20650.1932-6203http://nrs.harvard.edu/urn-3:HUL.InstRepos:5978615Scale invariance is a feature of complex biological systems, and abnormality of multi-scale behaviour may serve as an indicator of pathology. The hypothalamic suprachiasmatic nucleus (SCN) is a major node in central neural networks responsible for regulating multi-scale behaviour in measures of human locomotor activity. SCN also is implicated in the pathophysiology of bipolar disorder (BD) or manic-depressive illness, a severe, episodic disorder of mood, cognition and behaviour. Here, we investigated scaling behaviour in actigraphically recorded human motility data for potential indicators of BD, particularly its manic phase. A proposed index of scaling behaviour (Vulnerability Index [VI]) derived from such data distinguished between: [i] healthy subjects at high versus low risk of mood disorders; [ii] currently clinically stable BD patients versus matched controls; and [iii] among clinical states in BD patients.en-USbiologyneurosciencecognitive neurosciencecognitionbehavioral neurosciencemathematicsnonlinear dynamicsmedicinemental healthpsychiatrymood disordersneuropsychiatric disorderspsychologybehaviorphysicsinterdisciplinary physicssocial and behavorial sciencesJournal Article2011-12-2310.1371/journal.pone.0020650