We have created a computational model of the timing network that paces the heartbeat of the medicinal leech, Hirudo medicinalis. In the intact nerve cord, segmental oscillators are mutually entrained to the same cycle period. Although experiments have shown that the segmental oscillators are coupled by inhibitory coordinating interneurons, the underlying mechanisms of intersegmental coordination have not yet been elucidated. To help understand this coordination, we have created a simple computational model with two variants: symmetric and asymmetric. See references for more details. Biologically realistic network models with two, six, and eight cells and a tutorial are available at the links to Calabrese's web site below.

Model Type: Realistic Network

Region(s) or Organism(s): Leech

Cell Type(s): Leech heart interneuron

Currents: I Na,p; I Na,t; I K; I h; I Calcium; I Potassium

Model Concept(s): Activity Patterns; Bursting; Oscillations; Spatio-temporal Activity Patterns; Tutorial/Teaching; Action Potentials; Invertebrate

Simulation Environment: GENESIS

Implementer(s): Hill, Andrew A [aavhill at yahoo.com]

References:

Hill AA, Masino MA, Calabrese RL. (2002). Model of intersegmental coordination in the leech heartbeat neuronal network. Journal of neurophysiology. 87 [PubMed]

Hill AA, Lu J, Masino MA, Olsen OH, Calabrese RL. (2001). A model of a segmental oscillator in the leech heartbeat neuronal network. Journal of computational neuroscience. 10 [PubMed]