  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.
