Age-related effects on cortical thickness patterns of the Rhesus monkey brain

Abstract

The rhesus monkey is a useful model for examining age-related as well as other neurological and developmental effects on the brain, because of the extensive neuroanatomical homology to the human brain, the reduced occurrence of neurological diseases such as Alzheimer’s disease as well as the possibility of obtaining relevant behavioral data and post-mortem tissue for histological analyses. In this study, cortical thickness measurements based on a cortical surface modeling technique were applied for the first time to investigate cortical thickness patterns in the rhesus monkey brain, and were used to evaluate regional age related effects across a wide range of ages. Age-related effects were observed in several cortical areas, in particular in the somatosensory and motor cortices, where a robust negative correlation of cortical thickness with age was observed, similar to that found in humans. In contrast, results for monkeys compared to humans show significant inter-species differences in cortical thickness patterns in the frontal and the inferior temporal regions.

Age-related changes in human and non-human primate white matter: from myelination disturbances to cognitive decline

“…For example, at the microscopic level, some studies have reported a reduction of synapses in the non-human primate neocortex and other areas (Peters et al 1998;Peters et al 2008;Hara et al 2011) while others have reported loss of spines and atrophy of dendrites (Dumitriu et al 2010;Dickstein et al 2007). At a more global level, several studies using MRI methods have reported age-related reductions in the thickness or volume of the cerebral cortex or hippocampus (Alexander et al 2008;Koo et al 2012;Shamy et al 2011), a finding compatible with Fig. 1 Matched levels of T1 MRI scans are shown for a 6-yearold young female monkey (a) and a 24-year-old female monkey (b) where there is obvious enlargement of the atrium of the lateral ventricle.…”

Materials and technologies for soft implantable neuroprostheses

“…The brains of the main animal models used in neuroprosthetic research pale in comparison. For example, the weight of the brain and surface area of the cerebral cortex range from 1.8 g and 6 cm 2 for the adult rat 12 to 90 g and 110 cm 2 for the rhesus monkey 13 . The topologies of the brain also differ widely: small mammals have smooth brain surfaces, whereas the brains of primates (including humans) display complex external topographies and patterns of convolution that result from gyrification of the cortical surface 14 (FIG.…”

“…The cerebral cortex of humans -the outer, 2-3-mm-thick layer of grey matter over the brain hemispheres -is a highly convoluted structure, with more than half of its actual surface area hidden from the apparent, directly accessible outer brain surface. Typical sulci radii and gyri depths in the cortex of primates 13 are in the range of 1-5 mm. In the CNS, the cerebral and spinal tissues are protected by a multi-layered structure formed of meninges (that is, membranes including the pia mater, arachnoid mater and dura mater), bone, connective tissue and skin (FIG.…”

Microglia activation and phagocytosis: relationship with aging and cognitive impairment in the rhesus monkey

“…In searching for the neurobiological basis of agerelated cognitive impairments, quantitative MRI has shown that though gray matter cortical thickness is reduced (Alexander et al 2006;Koo et al 2010), total gray matter volume is preserved (Wisco et al 2008) and histological studies of gray matter have shown that neurons are not lost with age (e.g., Merrill et al 2000;Peters et al 1998). In contrast, both MRI and histological studies in monkeys and humans have shown that white matter volume is lost with age (Albert 1993;Guttmann et al 1998;Peters and Rosene 2003;Tang et al 1997;Wisco et al 2008).…”