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J Neurosci Methods. 2015 Apr 15;244:136-53. doi: 10.1016/j.jneumeth.2014.07.013. Epub 2014 Jul 30.

Multifractal analysis of information processing in hippocampal neural ensembles during working memory under Δ⁹-tetrahydrocannabinol administration.

Author information

1
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.
2
Dept. of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
3
Dept. of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA.
4
Dept. of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, NC, USA.

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.

NEW METHOD:

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.

COMPARISON WITH EXISTING 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.

CONCLUSION:

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.

KEYWORDS:

Cannabinoid; Cognition; Delayed non-match to sample; Electrophysiology; Wavelet leaders; Working memory

PMID:
25086297
PMCID:
PMC4312266
DOI:
10.1016/j.jneumeth.2014.07.013
[Indexed for MEDLINE]
Free PMC Article
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