Modeling cerebellar granular layer activity and evoked local field potential

Abstract

The cerebellum is known to be involved in several functions such as cognition, attention, and emotional response, in addition to performing motor coordination and learning. The somatosensory activity in the cerebellar granular layer corresponding to sensory and tactile input was studied by recording the LFPs (Local Field Potentials) from the Crus-IIa regions of the cerebellum in brain slices and in anesthetized animals. Theoretical modeling of cerebellar microcircuit and population activity based on electrophysiological experiments would aid in greater understandability of the neuronal basis of cerebellar function. The work described in this thesis focuses on modeling and reconstruction of granular layer LFP and development of LFPsim. Mainly two approaches were used to simulate the granular layer LFP: the first involves the use of a single granule neuron as a model kernel for reconstructing the population activity, and the second uses a detailed biophysical model of rat Crus-IIa cerebellar granular layer to generate the LFP. Point source approximation and line source approximation were used to reconstruct the network LFP. The thesis also involved the development of a novel LFP simulation tool, the LFPsim. The LFPsim was designed for modeling the extracellular field potential from the biophysical model of single neuron and networks. Induced plasticity conditions were simulated to estimate the granule neuron activation related to population responses. The network simulations distinctly displayed the TC wave components generated by independent granule neuron populations. The spatial reach of LFP waves was simulated using a network model to estimate the neuronal area contributed to the population response during somatosensory function. The mechanism also allowed for the generation of Multi Electrode Array-like field recordings at different array sizes for predicting network function / dysfunctions. ...