Chimpanzee (Pan troglodytes) precentral corticospinal system asymmetry and handedness: a diffusion magnetic resonance imaging study.
BACKGROUND
Most humans are right handed, and most humans exhibit left-right asymmetries of the precentral corticospinal system. Recent studies indicate that chimpanzees also show a population-level right-handed bias, although it is less strong than in humans.


RESULTS
We used in vivo diffusion-weighted and T1-weighted magnetic resonance imaging (MRI) to study the relationship between the corticospinal tract (CST) and handedness in 36 adult female chimpanzees. Chimpanzees exhibited a hemispheric bias in fractional anisotropy (FA, left>right) and mean diffusivity (MD, right>left) of the CST, and the left CST was centered more posteriorly than the right. Handedness correlated with central sulcus depth, but not with FA or MD.


CONCLUSIONS
These anatomical results are qualitatively similar to those reported in humans, despite the differences in handedness. The existence of a left>right FA, right>left MD bias in the corticospinal tract that does not correlate with handedness, a result also reported in some human studies, suggests that at least some of the structural asymmetries of the corticospinal system are not exclusively related to laterality of hand preference.
Li
Longchuan
L
Biomedical Imaging Technology Center, Emory University, Atlanta, Georgia, USA.
Preuss
Todd M
TM
Rilling
James K
JK
Hopkins
William D
WD
Glasser
Matthew F
MF
Kumar
Bhargav
B
Nana
Roger
R
Zhang
Xiaodong
X
Hu
Xiaoping
X
D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D007839:Functional Laterality; D002679:Pan troglodytes / Q000502:physiology*; D011712:Pyramidal Tracts / Q000000981:diagnostic imaging*; D011859:Radiography