To examine brain substrates of stress physiology and cognitive functions affected by age, we measured plasma levels of cortisol and adrenocorticotropic hormone (ACTH), sensitivity to glucocorticoid negative feedback regulation, performance on learning and memory tests, and the volume of prefrontal brain regions in healthy 5-17 year old female squirrel monkeys. Sexual maturity occurs at 3 years, and the average maximum lifespan is 21 years. No age-related differences were discerned on initial spatial learning and memory tests, nor at baseline for levels of cortisol and ACTH. But older monkeys responded with larger stress-induced increases in ACTH due in part to diminished glucocorticoid sensitivity determined by administration of hydrocortisone. Older monkeys also made significantly more errors on tests of reversal learning and memory that required inhibition and cognitive flexibility. Contrary to evidence from human neuroimaging, neither prefrontal gray nor white matter volumes were diminished in older squ...

Brain reference atlases are important resources for assigning anatomical location to experimental data, and for planning and interpreting experimental results. Three-dimensional atlases can also serve as templates for spatial co-registration (integratio...

To bridge the gap between the bench and the bedside, we have developed a porcine middle cerebral artery occlusion (MCAO) ischemic stroke model. Due to similarities to humans in brain size, gyrencephalacy, and white matter content, this porcine model has...

Data on comparative neuroanatomy across cetacean (dolphin, porpoise, and whale) species is relatively scarce. Here we present a neuroanatomical study of two odontocete species from different families: the killer whale (Orcinus orca) and the Amazon River dolphin (Inia geoffrensis), from Delphinidae and Platanistidae, respectively. Magnetic Resonance Imaging (MRI) was used to examine adult postmortem brains of these two species. MRI allows visualization of brain structures in normal 3D arrangement without the artifacts associated with histological procedures. Additionally, 3D MRI datasets are compatible with geometric morphometric analyses not possible with histological samples. MR images were acquired on a 1.5 T GE high-gradient MRI scanner equipped with 8.3 software. Axial and coronal T-1 weighted scans were obtained as 2 mm thick contiguous sections with a matrix size of 512 x 512 and an in-plane resolution of 32 x 32 cm yielding a voxel size of 0.63 x 0.63 x 2.0 mm. Axial, coronal, and sagittal T-2 slice...

Background: Current imaging methods are unable to differentiate neuroinflammatory processes such as endothelial activation in acute stroke. We imaged activated endothelium in a mouse model of acute stroke using a novel iron oxide nanoparticle MRI contra...

Magnetic resonance imaging (MRI) is a valuable technique in the study of comparative neuroanatomy. MRIs allow visualization of the brain¹s structures in normal three-dimensional (3D) arrangement while avoiding the accumulation of artifacts associated with histological procedures. Additionally, 3D MRI datasets are compatible with geometric morphometric analyses not possible with histological samples. The Great Ape Aging Project, a comparative neurobiology of aging resource, has collected over 50 brain specimens of great apes on loan from zoological gardens and research centers. Using a 1.5 Tesla MRI scanner, high-resolution T1 and T2 weighted scans of postmortem brains (age range=19-51) from chimpanzees (n=10), gorillas (n=2), and orangutans (n=2) have been obtained in axial, coronal, and sagittal planes. 3D surface reconstructions have also been made. The high quality of these materials permitted the development of MRI-based brain anatomic atlases in these species with a high level of spatial resolution. T...

Functional magnetic resonance imaging (fMRI) was used in rats to study CNS effects of the dopamine D2/3 receptor agonist quinelorane in vivo. Male Sprague-Dawley rats (250-300g, n=5 per group) were anaesthetised (α-chloralose, 60mg/kg i.v. bolus, then 30mg/kg/hr) and scanned using multi-echo gradient echo imaging (TE=5,10 and 15ms, TR =460ms, 120 volumes in 2 hours). Quinelorane (30µg/kg, s.c.) or saline vehicle were randomly administered 30-60 minutes after scan initiation. Mean echo images were realigned, normalised to a rat-brain template and analysed using a general linear model[1]. Statistically significant signal intensity increases over controls (T>4.3, p<0.05) were detected within the nucleus accumbens, ventromedial striatum and olfactory nuclei. These results are consistent with previous microdialysis experiments where quinelorane, a potent D3 receptor agonist with high D3/D2 selectivity[2], reduced dopamine release in the nucleus accumbens and ventral striatum[3], areas rich in D3 receptors[2]. O...

Human hand dexterity depends on the ability to move digits independently and to combine these movements in various coordinative patterns. It is well established that the primary motor cortex (M1) is important for skillful digit actions but less is known about the role played by the nonprimary motor centers. Here we use functional magnetic resonance imaging to examine the hypothesis that nonprimary motor areas and the posterior parietal cortex are strongly activated when healthy humans move the right digits in a skillful coordination pattern involving relatively independent digit movements. A task in which flexion of the thumb is accompanied by extension of the fingers and vice versa, i.e., a learned “nonsynergistic” coordination pattern, is contrasted with a task in which all digits flex and extend simultaneously in an innate synergistic coordination pattern (opening and closing the fist). The motor output is the same in the two conditions. Thus, the difference when contrasting the nonsynergistic and syner...

Spinocerebellar Ataxia type 7 (SCA7) is an autosomal dominant neurodegenerative disease characterized by progressive cerebellar ataxia and retinal degeneration. Postmortem neuropathology has revealed that while atrophy is primarily restricted to the cer...

Cerebral cortical development involves complex changes in cellular architecture and connectivity that occur at regionally varying rates. Using diffusion tensor magnetic resonance imaging (DTI) to analyze cortical microstructure, previous studies have shown that cortical maturation is associated with a progressive decline in water diffusion anisotropy. We applied high-resolution DTI to fixed postmortem fetal baboon brains and characterized regional changes in diffusion anisotropy using surface-based visualization methods. Anisotropy values vary within the thickness of the cortical sheet, being higher in superficial layers. At a regional level, anisotropy at embryonic day 90 (E90; 0.5 term; gestation lasts 185 d in this species) is low in allocortical and periallocortical regions near the frontotemporal junction and is uniformly high throughout isocortex. At E125 (0.66 term), regions having relatively low anisotropy (greater maturity) include cortex in and near the Sylvian fissure and the precentral gyrus. B...