Local Field Potential Journey into the Basal Ganglia

TL;DR

This study investigates the origin of local field potentials in the basal ganglia by recording from a primate model and developing a novel method to distinguish between synaptic input and volume conduction, revealing two main pathways of signal propagation.

Contribution

The paper introduces a new method to differentiate between synaptic input and volume conduction in LFP signals and identifies two major pathways of potential flow in the basal ganglia.

Findings

Identified two main pathways of LFP propagation from cortex to basal ganglia.

Developed a novel method to distinguish between information flow and volume conduction.

Found that LFP signals may represent both synaptic activity and electrical signal flow.

Abstract

Local Field potential (LFP) in the basal ganglia (BG) nuclei in the brain have attracted much research and clinical interest. However, the origin of this signal is still under debate throughout the last decades. The question is whether it is a local subthreshold phenomenon, synaptic input to neurons or it is a flow of electrical signals merged as volume conduction which are generated from simultaneous firing neurons in the cerebral cortex and obeys the Maxwell equations. In this study, we recorded in a monkey brain simultaneously LFP's from the cerebral cortex, in the frontal lobe and primary motor cortex (M1) and in sites in all BG nuclei: the striatum, globus pallidus, and subthalamic nucleus. All the records were taken from human primate model (vervet monkey), during spontaneous activity. Developing and applying a novel method to identify significant cross-correlations (potential links) while removing "spurious" correlations, we found a tool that may discriminate between the two major phenomena of synaptic inputs (as we define as information flow) and volume conduction. We find mainly two major paths flows of field potential, that propagates with two different time delays, from the primary motor cortex, and from the frontal cortex. Our results indicate that the two path flows may represent the two mechanisms of volume conduction and information flow.