Comparison of the basal ganglia in rats, marmosets, macaques, baboons, and humans: Volume and neuronal number for the output, internal relay, and striatal modulating nuclei

Abstract

This study compares the basal ganglia of rats, marmosets, macaques, baboons, and humans. It uses established protocols to estimate the volume and number of neurons within the output nuclei (internal globus pallidus, IGP; and nondopaminergic substantia nigra, SNND), two internal relay and modulating nuclei (subthalamic nucleus, STh; and external globus pallidus, EGP), and a modulator of the striatum (dopaminergic substantia nigra, SND). Nuclear boundaries were defined by using immunohistochemistry for striatal afferents. Total numbers of Nissl-stained and parvalbumin-immunoreactive neurons were calculated by using the fractionator technique. Comparisons between species were standardized relative to brain mass (rats < marmosets < macaques < baboons < humans). The EGP consistently had more neurons relative to the IGP, STh, and SND, which had similar neuronal numbers within each species. The SNND had proportionally more neurons in rats than in primates (especially humans). The distribution of SND neurons varied substantially between rats and primates (very few ventrally located neurons in rats) with humans containing fewer SND neurons than other primates. The reduction in SND neurons in humans suggests less dopaminergic regulation of the basal ganglia system compared with other species. The consistency in the number of IGP neurons across all species, combined with the reduction in SNND neurons in humans, suggests a greater emphasis on output pathways through the IGP and that there are proportionally more STh and EGP neurons in humans.

Reversible Demyelination, Blood-Brain Barrier Breakdown, and Pronounced Neutrophil Recruitment Induced by Chronic IL-1 Expression in the Brain

“…Similar number of neurons was counted throughout the striatum of animals injected with AdIL-1 or Ad␤gal at the peak of transgene expression (14 days). This number was the expected one for an undamaged striatum 39 and was comparable to the number of neurons present in rat striata 30 days after AdIL-1 administration. This last observation rules out a non-specific effect of the adenoviral vector that could have reduced neuronal numbers nonspecifically in the previous groups (AdIL-1-and Ad␤gal-injected animals 14 days post-treatment).…”

The human lateral tuberal nucleus: Immunohistochemical characterization and analogy to the rodent PV1-nucleus

“…Likewise, a quantitative comparison of the basal ganglia in the rats, monkeys and humans has revealed marked anatomical and neurochemical differences between these species (Hardman et al, 2002).…”

The effects of cocaine: A shifting target over the course of addiction

“…In addition, because monkeys have greater than 95% gene homology with humans (Hacia et al, 1998), they are more similar to humans in terms of phylogeny, anatomy, physiology and behavior than many other species. For example, nonhuman primates share considerable cytoarchitectural, neurochemical, and ultrastructural similarities with humans, particularly when considering the prefrontal cortex and basal ganglia Price, 1994, 1996;Porrino and Lyons, 2000;Hardman et al, 2002). Furthermore, the connectivity patterns of the prefrontal cortex as well as other brain regions of nonhuman primates are highly homologous to those of humans (Ongur et al, 2003).…”