To understand the spike-timing detection mechanisms in cerebellar long-term depression (LTD), we developed a kinetic model of Ca dynamics within a Purkinje dendritic spine. In our kinetic simulation, IP3 was first produced via the metabotropic pathway of parallel fiber (PF) inputs, and the Ca influx in response to the climbing fiber (CF) input triggered regenerative Ca-induced Ca release from the internal stores via the IP3 receptors activated by the increased IP3. The delay in IP3 increase caused by the PF metabotropic pathway generated the optimal PF–CF interval. The Ca dynamics revealed a threshold for large Ca2 release that decreased as IP3 increased, and it coherently explained the different forms of LTD. See paper for more and details.

Model Type: Synapse

Cell Type(s): Cerebellum Purkinje GABA cell

Currents: I Calcium

Receptors: IP3

Transmitters: Glutamate

Model Concept(s): Coincidence Detection; Synaptic Plasticity; Depression; Signaling pathways; Calcium dynamics

Simulation Environment: GENESIS (web link to model); MATLAB

References:

Doi T, Kuroda S, Michikawa T, Kawato M. (2005). Inositol 1,4,5-trisphosphate-dependent Ca2+ threshold dynamics detect spike timing in cerebellar Purkinje cells. The Journal of neuroscience : the official journal of the Society for Neuroscience. 25 [PubMed]