Point source stimulation of dendrites of a pyramidal cell in python

Abstract

Extracellular electrical stimulation of neuronal cells is an actively researched area. It is of interest under what circumstances electrical stimulation can initiate an action potential (AP). Unlike in the case of intracellular stimulation where current is injected through a patch-clamp directly into the cell, extracellular stimulation allows for a more flexible position of the electrode outside of the cell. During stimulation, zones of hyper-, as well as depolarization come into appearance which have interesting consequences for this thesis. A compartmental model of a real L5 pyramidal cell was used for testing purposes. The pyramidal neuron was reconstructed in a Python programmed framework, serving as a high-level API to the software NEURON based on the HOC interpreter language. Unlike earlier models, this one incorporated sensitive calcium ion-channel dynamics. This is a very important feature that allows studying effects like synaptic integration in the apical dendrites and calcium-driven AP-generation. In the case of intracellular stimulation, we will study the effect of calcium-driven AP-generation in the apical dendrites as well as their influence on soma AP form. In the case of extracellular stimulation, we study the influence of electrode positioning in long- and mid-range distance, as well as lateral to the soma. Regarding the latter, we focus on the influence on basal dendrites, the soma, and the axon.