title: Fractal stochastic modeling of spiking activity in suprachiasmatic nucleus neurons.
abstract: Individual neurons in the suprachiasmatic nucleus (SCN), the master biological clock in mammals, autonomously produce highly complex patterns of spikes. We have shown that most (approximately 90%) SCN neurons exhibit truly stochastic interspike interval (ISI) patterns. The aim of this study was to understand the stochastic nature of the firing patterns in SCN neurons by analyzing the ISI sequences of 150 SCN neurons in hypothalamic slices. Fractal analysis, using the periodogram, Fano factor, and Allan factor, revealed the presence of a 1/f-type power-law (fractal) behavior in the ISI sequences. This fractal nature was persistent after the application of the GABAA receptor antagonist bicuculline, suggesting that the fractal stochastic activity is an intrinsic property of individual SCN neurons. Based on these physiological findings, we developed a computational model for the stochastic SCN neurons to find that their stochastic spiking activity was best described by a gamma point process whose mean firing rate was modulated by a fractal binomial noise. Taken together, we suggest that SCN neurons generate temporal spiking patterns using the fractal stochastic point process.
authors.affiliation: National Creative Research Initiative Center for Neurodynamics and Department of Physics, Korea University, Seoul 136-701, South Korea.
authors.forename: Sung-Il
authors.initials: SI
authors.lastname: Kim
authors.forename: Jaeseung
authors.initials: J
authors.lastname: Jeong
authors.forename: Yongho
authors.initials: Y
authors.lastname: Kwak
authors.forename: Yang In
authors.initials: YI
authors.lastname: Kim
authors.forename: Seung Hun
authors.initials: SH
authors.lastname: Jung
authors.forename: Kyoung J
authors.initials: KJ
authors.lastname: Lee
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D003198:Computer Simulation; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013269:Stochastic Processes; D013493:Suprachiasmatic Nucleus / Q000166:cytology*; D013997:Time Factors
chemical_list: D018756:GABA Antagonists; D001640:Bicuculline