title: Multifractal analysis of information processing in hippocampal neural ensembles during working memory under Δ⁹-tetrahydrocannabinol administration.
abstract: BACKGROUND
  Multifractal analysis quantifies the time-scale-invariant properties in data by describing the structure of variability over time. By applying this analysis to hippocampal interspike interval sequences recorded during performance of a working memory task, a measure of long-range temporal correlations and multifractal dynamics can reveal single neuron correlates of information processing.
  
  
  METHODS
  Wavelet leaders-based multifractal analysis (WLMA) was applied to hippocampal interspike intervals recorded during a working memory task. WLMA can be used to identify neurons likely to exhibit information processing relevant to operation of brain-computer interfaces and nonlinear neuronal models.
  
  
  RESULTS
  Neurons involved in memory processing ("Functional Cell Types" or FCTs) showed a greater degree of multifractal firing properties than neurons without task-relevant firing characteristics. In addition, previously unidentified FCTs were revealed because multifractal analysis suggested further functional classification. The cannabinoid type-1 receptor (CB1R) partial agonist, tetrahydrocannabinol (THC), selectively reduced multifractal dynamics in FCT neurons compared to non-FCT neurons.
  
  
  METHODS
  WLMA is an objective tool for quantifying the memory-correlated complexity represented by FCTs that reveals additional information compared to classification of FCTs using traditional z-scores to identify neuronal correlates of behavioral events.
  
  
  CONCLUSIONS
  z-Score-based FCT classification provides limited information about the dynamical range of neuronal activity characterized by WLMA. Increased complexity, as measured with multifractal analysis, may be a marker of functional involvement in memory processing. The level of multifractal attributes can be used to differentially emphasize neural signals to improve computational models and algorithms underlying brain-computer interfaces.
authors.affiliation: Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, NC, USA; Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA. Electronic address: dfetterh@wakehealth.edu.
authors.forename: Dustin
authors.initials: D
authors.lastname: Fetterhoff
authors.affiliation: Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Ioan
authors.initials: I
authors.lastname: Opris
authors.affiliation: Dept. of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Sean L
authors.initials: SL
authors.lastname: Simpson
authors.affiliation: Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Sam A
authors.initials: SA
authors.lastname: Deadwyler
authors.affiliation: Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Hampson
authors.affiliation: Dept. of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kraft
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000465:Algorithms; D000704:Analysis of Variance; D000818:Animals; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000008:administration & dosage*; D001330:Electronic Data Processing; D006624:Hippocampus / Q000166:cytology*; D008570:Memory, Short-Term / Q000187:drug effects*; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D017711:Nonlinear Dynamics; D011619:Psychotropic Drugs / Q000008:administration & dosage*; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D011619:Psychotropic Drugs; D013759:Dronabinol
keywords: Cannabinoid; Cognition; Delayed non-match to sample; Electrophysiology; Wavelet leaders; Working memory
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