Local field potential journey into the Basal Ganglia

Abstract

Local field potentials (LFP) in the basal ganglia (BG) have attracted considerable research and clinical interest. The genesis of these signals has been a topic of extensive discourse, focusing on whether they are a manifestation of local synaptic activity or result from the propagation of electrical signals through tissue, as described by the Maxwell equations (volume conduction). To investigate this, we conducted simultaneous recordings of LFPs from two cortical areas— the dorsolateral prefrontal cortex (DLPFC) and the primary motor cortex (M1)—and various sites within the BG nuclei in an awake, non-task-engaged non-human primate (NHP). Employing innovative analytical techniques, we discerned significant cross-correlations indicative of potential connections, while filtering out non-significant correlations. This allowed us to differentiate between synaptic inputs and volume conduction. Our findings indicate two distinct propagation pathways of BG field potentials emanating from the M1 and the DLPFC, each characterized by different temporal delays. The results imply that these anatomical pathways are differentially influenced by the mechanisms of volume conduction and synaptic transmission. Notably, the M1 exhibits more functional links with non-zero-time delays to the BG structures, while the DLPFC-BG connections are marked by zero-time delays, suggesting a predominance of volume conduction effects. Consequently, investigations into the origins of BG LFP should account for the distinct anatomical pathways linking the cortex and the BG, as they differentially represent information flow and volume conductance.