Comparative connectivity of frontal eye field and striatum between humans and macaques

Abstract

Classically, the cortico-basal ganglia circuits has been described in terms of segregated ocular motor and skeletal motor loops. The ocular motor loop begins with projections from the frontal eye fields (FEF) to the caudate nucleus, and the skeletal motor loop begins with projections from the motor cortex (M1) to the putamen. This description has been guided by anatomical and physiological findings in macaques. Recent neuroimaging studies of the human FEF reveal inconsistencies with this organization. Using probabilistic diffusion tractography, we compared the in-vivo pattern of connectivity between humans and macaques. Nine healthy humans were scanned at the UMC Utrecht. Nine healthy adult macaques were scanned at Vanderbilt University Institute of Imaging Science. All subjects were imaged in the same type of scanner (Phillips Achieva 3T) with similar pulse sequences and analysis pipelines. We found that the FEF cortico-strial pathways differed between macaques and humans. In macaques the FEF is connected with the head of the caudate and dorsomedial putamen, in agreement with neuroanatomical tract tracer findings. However, in humans FEF is connected to posterior putamen and a small portion of the caudate body. The differences in connectivity may be explained by the evolutionary expansion of prefrontal projections to striatum in humans.

Meeting abstract presented at VSS 2014