Network for Biological Invasions and Dispersal Research

MITACS Seminar at the University of New Brunswick, Fredericton

Thursday, 9 October, 2008,

Dr. Muhammad Dur-e-Ahmad

University of New Brunswick, Saint John

will speak on

Structural Plasticity of Dendritic Spines: A Computational Study

2:30 PM, Tilley Hall 403

Abstract: Recent evidence indicates that the morphology and density of dendritic spines are regulated during synaptic plasticity. High frequency stimuli, that induce long term potentiation (LTP) have been associated with the increase in number and size of spines. In contrast, low frequency stimuli that induce long term depression (LTD) are associated with decreases in the number and size of spines. Decreases in spine density also occur due to excitotoxicity with the very high level of activity such as seizures. In this work, a model is presented to investigate the calcium dependent structural plasticity of the spines. This model is based on the standard dimensionless cable equation for the change in membrane potential in the passive dendrite. Additional equations characterize the change in potential in spine head, calcium dynamics in spine head and calcium dependent changes in spine structure and density along the dendrite. We used the computational study to observe the effects of low and high-frequency synaptic activation to dendritic spines. The model is formulated so that this long-term potentiation-inducing stimulus eventually leads to structural stability. In contrast, a prolonged low-frequency stimulation paradigm that would typically induce long-term depression results in a decrease in stem resistance (correlated with stem shortening) and an eventual decrease in spine density. Finally, on the computational side, new algorithms based on the Chebyshev spectral collocation method are introduced and the results are compared with the finite different schemes.