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Summer Research Fellowship Programme of India's Science Academies

QUANTIFICATION AND INTERPRETATION OF SPIKE-LFP RELATIONSHIP THROUGH SPIKE TRIGGERED AVERAGE

Raj Kumari Sharma

Department of Biosciences & Bioengineering, Indian Institute of Technology, Bombay

Dr. Supatim Ray

Centre for Neuroscience, Indian Institute of Science, Banglore

Abstract

Electrophysiological data obtained from visual areas in the brain contain ample information. The analysis of such data, can help us understand the neural basis of cognitive functions in vision. Neuronal activity in the brain gives rise to transmembrane and synaptic currents that contribute to generate an extra-cellular potential which can be measured using micro-electrodes. This potential, generated by the combined activity of a large population of neurons is called Local Field Potential (LFP). The strongest currents across the neuronal membrane are generated by fast action potentials and can be detected as a ‘unit’ or ‘spike’ activity. The synchronous spiking activity of various neurons can effectively contribute to high frequency components of LFP. LFP is obtained by low pass filtering the extracellular signal recorded from microelectrodes. Any causal filter necessarily introduces a delay in the signal which can hamper the observations. Previous studies have shown that butterworth filter results in group delay in the case of filtered stLFP (Spike Triggered LFP) as compared to uncorrected stLFP. Analysis of stLFPs from different task protocols can lead to significant observations that can contribute to improvise the efficacy of the treatment protocols available to treat patients with neurological disorders.

Keywords: Neuron, Cognition, Vision, Synaptic Currents, Spike, Local Field Potential

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