title: Bursting as a source of non-linear determinism in the firing patterns of nigral dopamine neurons.
abstract: Nigral dopamine (DA) neurons in vivo exhibit complex firing patterns consisting of tonic single-spikes and phasic bursts that encode information for certain types of reward-related learning and behavior. Non-linear dynamical analysis has previously demonstrated the presence of a non-linear deterministic structure in complex firing patterns of DA neurons, yet the origin of this non-linear determinism remains unknown. In this study, we hypothesized that bursting activity is the primary source of non-linear determinism in the firing patterns of DA neurons. To test this hypothesis, we investigated the dimension complexity of inter-spike interval data recorded in vivo from bursting and non-bursting DA neurons in the chloral hydrate-anesthetized rat substantia nigra. We found that bursting DA neurons exhibited non-linear determinism in their firing patterns, whereas non-bursting DA neurons showed truly stochastic firing patterns. Determinism was also detected in the isolated burst and inter-burst interval data extracted from firing patterns of bursting neurons. Moreover, less bursting DA neurons in halothane-anesthetized rats exhibited higher dimensional spiking dynamics than do more bursting DA neurons in chloral hydrate-anesthetized rats. These results strongly indicate that bursting activity is the main source of low-dimensional, non-linear determinism in the firing patterns of DA neurons. This finding furthermore suggests that bursts are the likely carriers of meaningful information in the firing activities of DA neurons.
authors: Department of Psychiatry, Columbia College of Physicians and Surgeons, New York, NY, USA. jsjeong@kaist.ac.kr
authors: Jaeseung
authors: J
authors: Jeong
authors: Wei-Xing
authors: WX
authors: Shi
authors: Ralph
authors: R
authors: Hoffman
authors: Jihoon
authors: J
authors: Oh
authors: John C
authors: JC
authors: Gore
authors: Benjamin S
authors: BS
authors: Bunney
authors: Bradley S
authors: BS
authors: Peterson
mesh_terms: D000200:Action Potentials; D000818:Animals; D059290:Dopaminergic Neurons / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000166:cytology / Q000502:physiology*