A COMPUTATIONAL STUDY OF REBOUND RESPONSES IN A CONDUCTANCE-BASED MODEL OF A DEEP CEREBELLAR NUCLEUS CELL

D.Jaeger1*; E.De Schutter2; V.Steuber2

1. Biology, 2006 Rollins Research Ctr., Atlanta, GA, USA 2. Theoretical NeuroBiology, Univ. of Antwerp, Antwerp, Belgium

The deep cerebellar nuclei (DCN) provide the main output from the cerebellum. Neurons in the DCN receive excitatory inputs from mossy fibers and climbing fibers, and inhibitory input from Purkinje cells in the cerebellar cortex. Three different types of DCN neurons have been described: large glutamatergic neurons, which project to the thalamus, red nucleus and other brain stem nuclei, smaller GABAergic projection neurons, and even smaller inhibitory interneurons. Previous electrophysiological recordings of large DCN neurons in vitro have shown that a prominent feature of these neurons are rebound depolarization (RD) responses after the offset of hyperpolarizing current injections that vary in their intensity and length. RD responses are also observed in vitro after high frequency bursts of inhibitory postsynaptic potentials (IPSPs) elicited by stimulation of Purkinje cell axons. Despite the clear presence of RD responses in vitro, the physiological relevance of these responses in vivo is controversial. We have constructed an active multi-compartmental model of a large excitatory DCN neuron in order to study the possible mechanisms contributing to different forms of the RD response. Depending on the amplitudes and kinetics of low threshold calcium currents, persistent sodium currents and h currents, and the intracellular calcium dynamics, our model can generate RD responses of varying intensity and length, matching time courses that are observed in vitro. We use a brute force database based parameter search approach to evaluate the performance and robustness of the model. The generation of RD responses in the model is compared for current injection and synaptic input, and for in vitro and in vivo conditions, and the implications for RD responses in DCN neurons in vivo is examined. Support Contributed By: NIMH RO1-MH065634

Citation:D. Jaeger, E. De Schutter, V. Steuber. A COMPUTATIONAL STUDY OF REBOUND RESPONSES IN A CONDUCTANCE-BASED MODEL OF A DEEP CEREBELLAR NUCLEUS CELL Program No. 179.11. 2005 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2005. Online.