RT Journal Article
SR Electronic
T1 Cortico–Amygdala–Striatal Circuits Are Organized as Hierarchical Subsystems through the Primate Amygdala
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 14017
OP 14030
DO 10.1523/JNEUROSCI.0170-13.2013
VO 33
IS 35
A1 Youngsun T. Cho
A1 Monique Ernst
A1 Julie L. Fudge
YR 2013
UL http://www.jneurosci.org/content/33/35/14017.abstract
AB The prefrontal and insula cortex, amygdala, and striatum are key regions for emotional processing, yet the amygdala's role as an interface between the cortex and striatum is not well understood. In the nonhuman primate (Macaque fascicularis), we analyzed a collection of bidirectional tracer injections in the amygdala to understand how cortical inputs and striatal outputs are organized to form integrated cortico–amygdala–striatal circuits. Overall, diverse prefrontal and insular cortical regions projected to the basal and accessory basal nuclei of the amygdala. In turn, these amygdala regions projected to widespread striatal domains extending well beyond the classic ventral striatum. Analysis of the cases in aggregate revealed a topographic colocalization of cortical inputs and striatal outputs in the amygdala that was additionally distinguished by cortical cytoarchitecture. Specifically, the degree of cortical laminar differentiation of the cortical inputs predicted amygdalostriatal targets, and distinguished three main cortico–amygdala–striatal circuits. These three circuits were categorized as “primitive,” “intermediate,” and “developed,” respectively, to emphasize the relative phylogenetic and ontogenetic features of the cortical inputs. Within the amygdala, these circuits appeared arranged in a pyramidal-like fashion, with the primitive circuit found in all examined subregions, and subsequent circuits hierarchically layered in discrete amygdala subregions. This arrangement suggests a stepwise integration of the functions of these circuits across amygdala subregions, providing a potential mechanism through which internal emotional states are managed with external social and sensory information toward emotionally informed complex behaviors.