title: Mouse activity across time scales: fractal scenarios.
abstract: In this work we devise a classification of mouse activity patterns based on accelerometer data using Detrended Fluctuation Analysis. We use two characteristic mouse behavioural states as benchmarks in this study: waking in free activity and slowwave sleep (SWS). In both situations we find roughly the same pattern: for short time intervals we observe high correlation in activity--a typical 1/f complex pattern--while for large time intervals there is anti-correlation. High correlation of short intervals (0.01 s to 2 s: waking state and 0.01 s to 0.1 s: SWS) is related to highly coordinated muscle activity. In the waking state we associate high correlation both to muscle activity and to mouse stereotyped movements (grooming, waking, etc.). On the other side, the observed anti-correlation over large time scales (30 s to 300 s: waking state and 0.3 s to 5 s: SWS) during SWS appears related to a feedback autonomic response. The transition from correlated regime at short scales to an anti-correlated regime at large scales during SWS is given by the respiratory cycle interval, while during the waking state this transition occurs at the time scale corresponding to the duration of the stereotyped mouse movements. Furthermore, we find that the waking state is characterized by longer time scales than SWS and by a softer transition from correlation to anticorrelation. Moreover, this soft transition in the waking state encompass a behavioural time scale window that gives rise to a multifractal pattern. We believe that the observed multifractality in mouse activity is formed by the integration of several stereotyped movements each one with a characteristic time correlation. Finally, we compare scaling properties of body acceleration fluctuation time series during sleep and wake periods for healthy mice. Interestingly, differences between sleep and wake in the scaling exponents are comparable to previous works regarding human heartbeat. Complementarily, the nature of these sleep-wake dynamics could lead to a better understanding of neuroautonomic regulation mechanisms.
authors.affiliation: Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil; Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts, United States of America.
authors.forename: G Z dos Santos
authors.initials: GZ
authors.lastname: Lima
authors.affiliation: Centro de Biofísica, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: B
authors.initials: B
authors.lastname: Lobão-Soares
authors.affiliation: Departamento de Engenharia Biomédica, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: G C
authors.initials: GC
authors.lastname: do Nascimento
authors.affiliation: Brain Institute, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: Arthur S C
authors.initials: AS
authors.lastname: França
authors.affiliation: Centro de Biofísica, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Muratori
authors.affiliation: Brain Institute, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: S
authors.initials: S
authors.lastname: Ribeiro
authors.affiliation: Centro de Biofísica, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
authors.forename: G
authors.initials: G
authors.lastname: Corso
mesh_terms: D061725:Accelerometry; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D017709:Fractals; D006801:Humans; D008810:Mice, Inbred C57BL; D012146:Rest / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*