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. 2014 May 21:569:38-42.
doi: 10.1016/j.neulet.2014.03.047. Epub 2014 Mar 29.

Effect of age and calorie restriction on corpus callosal integrity in rhesus macaques: a fiber tractography study

Aadhavi Sridharan  1 , Barbara B Bendlin  2 , Catherine L Gallagher  3 , Jennifer M Oh  2 , Auriel A Willette  2 , Andrew L Alexander  4 , Joseph W Kemnitz  5 , Ricki J Colman  6 , Richard H Weindruch  7 , Sterling C Johnson  2
Affiliations

Effect of age and calorie restriction on corpus callosal integrity in rhesus macaques: a fiber tractography study

Aadhavi Sridharan et al. Neurosci Lett. .

Abstract

The rhesus macaque exhibits age-related brain changes similar to humans, making an excellent model of normal aging. Calorie restriction is a dietary intervention that reduces age-related comorbidities in short-lived animals, and its effects are still under study in rhesus macaques. Here, using deterministic fiber tracking method, we examined the effects of age and calorie restriction on a diffusion tensor imaging measure of white matter integrity, fractional anisotropy (FA), within white matter tracks traversing the anterior (genu) and posterior (splenium) corpus callosum in rhesus monkeys. Our results show: (1) a significant inverse relationship between age and mean FA of tracks traversing the genu and splenium; (2) higher mean FA of the splenium tracks as compared to that of genu tracks across groups; and (3) no significant diet effect on mean track FA through either location. These results are congruent with the age-related decline in white matter integrity reported in humans and monkeys, and the anterior-to-posterior gradient in white matter vulnerability to normal aging in humans. Further studies are warranted to critically evaluate the effect of calorie restriction on brain aging in this unique cohort of elderly primates.

Keywords: Aging; Corpus callosum; Diffusion tensor imaging; Macaque; Tractography.

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Conflict of interest statement

Disclosure Statement

The authors report no conflicts of interest or relevant financial interests related to this work.

Figures

Figure 1
Figure 1. Fiber tractography in rhesus macaque corpus callosum
A representative image of deterministic fiber tractography from a 26-year-old calorie-restricted male rhesus monkey is shown in native space (T2-weighted image). Fibers traversing the 5mm spherical seed placed in the (A) genu (green) and (B) splenium (yellow) of corpus callosum in coronal view; the insets display the relative placement of the spheres in sagittal view. R = right, L = left. Fiber tracks are color coded based on directionality (anterior/posterior = blue, medial/lateral = red, superior/inferior = green).
Figure 2
Figure 2. Mean FA of genu and splenium fibers of corpus callosum in rhesus monkeys
Mean FA within posterior corpus callosum (splenium) fiber tracks was significantly greater than that of anterior corpus callosum (genu) fiber tracks in a combined analysis of control and calorie-restricted animals (t = −15.4, p < 0.001). Error bars represent standard deviation.
Figure 3
Figure 3. Correlation between age and mean FA of corpus callosal fibers
There is a significant inverse relationship between age and mean FA of fibers traversing the (A) genu (t = −2.54, p = 0.017) and (B) splenium of the corpus callosum (t = −2.20, p = 0.036) in a combined analysis of control and calorie-restricted animals.
See this image and copyright information in PMC

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