title: Quantifying memory in complex physiological time-series.
abstract: In a time-series, memory is a statistical feature that lasts for a period of time and distinguishes the time-series from a random, or memory-less, process. In the present study, the concept of "memory length" was used to define the time period, or scale over which rare events within a physiological time-series do not appear randomly. The method is based on inverse statistical analysis and provides empiric evidence that rare fluctuations in cardio-respiratory time-series are 'forgotten' quickly in healthy subjects while the memory for such events is significantly prolonged in pathological conditions such as asthma (respiratory time-series) and liver cirrhosis (heart-beat time-series). The memory length was significantly higher in patients with uncontrolled asthma compared to healthy volunteers. Likewise, it was significantly higher in patients with decompensated cirrhosis compared to those with compensated cirrhosis and healthy volunteers. We also observed that the cardio-respiratory system has simple low order dynamics and short memory around its average, and high order dynamics around rare fluctuations.
authors.affiliation: Computational Physical Sciences Research Laboratory, School of Nano-Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran.
authors.forename: Amir H
authors.initials: AH
authors.lastname: Shirazi
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Raoufy
authors.forename: Haleh
authors.initials: H
authors.lastname: Ebadi
authors.forename: Michele
authors.initials: M
authors.lastname: De Rui
authors.forename: Sami
authors.initials: S
authors.lastname: Schiff
authors.forename: Roham
authors.initials: R
authors.lastname: Mazloom
authors.forename: Sohrab
authors.initials: S
authors.lastname: Hajizadeh
authors.forename: Shahriar
authors.initials: S
authors.lastname: Gharibzadeh
authors.forename: Ahmad R
authors.initials: AR
authors.lastname: Dehpour
authors.forename: Piero
authors.initials: P
authors.lastname: Amodio
authors.forename: G Reza
authors.initials: GR
authors.lastname: Jafari
authors.forename: Sara
authors.initials: S
authors.lastname: Montagnese
authors.forename: Ali R
authors.initials: AR
authors.lastname: Mani
mesh_terms: D000328:Adult; D000465:Algorithms; D001249:Asthma / Q000503:physiopathology; D064368:Healthy Volunteers; D006339:Heart Rate; D006801:Humans; D008103:Liver Cirrhosis / Q000503:physiopathology; D008568:Memory / Q000502:physiology*; D008954:Models, Biological; D015233:Models, Statistical; D011336:Probability; D012119:Respiration; D013997:Time Factors; D055815:Young Adult
references.citation: Am J Physiol Gastrointest Liver Physiol. 2009 Feb;296(2):G330-8
references.pmid: 19023029
references.citation: Crit Care Med. 2004 Jul;32(7):1542-5
references.pmid: 15241099
references.citation: Comp Biochem Physiol A Mol Integr Physiol. 1999 Dec;124(4):447-60
references.pmid: 10682243
references.citation: Ann Med. 1997 Aug;29(4):321-5
references.pmid: 9375990
references.citation: Ann N Y Acad Sci. 1987;504:16-32
references.pmid: 3477113
references.citation: Nature. 2005 Dec 1;438(7068):667-70
references.pmid: 16319891
references.citation: J Biol Phys. 2006 Oct;32(2):117-28
references.pmid: 19669455
references.citation: Chaos. 2009 Jun;19(2):028501
references.pmid: 19566276
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Apr;83(4 Pt 2):046319
references.pmid: 21599307
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2009 May;79(5 Pt 2):056202
references.pmid: 19518531
references.citation: J Allergy Clin Immunol. 2007 Nov;120(5 Suppl):S94-138
references.pmid: 17983880
references.citation: Lancet. 2008 Sep 20;372(9643):1088-99
references.pmid: 18805337
references.citation: Liver Transpl. 2000 Jul;6(4 Suppl 1):S44-52
references.pmid: 10915191
references.citation: Hepatology. 2005 Nov;42(5):1203-5
references.pmid: 16250041
references.citation: Eur Respir J. 2005 Jan;25(1):186-99
references.pmid: 15640341
references.citation: Nat Clin Pract Gastroenterol Hepatol. 2006 Jun;3(6):329-37
references.pmid: 16741552
references.citation: Lancet. 1996 May 11;347(9011):1312-4
references.pmid: 8622511
references.citation: Br J Surg. 1973 Aug;60(8):646-9
references.pmid: 4541913
references.citation: Respirology. 2013 Jan;18(1):108-16
references.pmid: 22897148