Establishing a primate brain connectivity and linking it function and human diseases remain an elusive goal. Diffusion MRI, which quantifies the magnitude and anisotropy of water diffusion in brain tissues, offers unparalleled opportunity to link the ma...

Our visual system can rapidly and effortlessly detect a salient object in a cluttered visual scene. Recent electrophysiological studies in monkeys and functional MRI studies in humans suggest that such efficient detection of the salient object involves ...

To single out visual perceptual impairment in children with multiple handicap, Stiers ea. (Brain Dev 21:397) evaluated visual perception against non-verbal intelligence. This procedure revealed impaired visual categorization of suboptimal object presentations in children with early ischaemic brain damage, but not in a control group with mental retardation. To confirm that these impairments are perceptual in nature, 3 children (7-10 yr.) with divers clinical features but impairment on the visual perception battery L94 relative to their non-verbal intelligence, underwent a structural MRI scan to ascertain whether their brain lesions converged in visual neural structures. All had spastic diplegia following preterm birth. Visual acuity was between 0.5 and 1.0. In addition, one child with periventricular leukomalacia (PVL) had normal IQ but specific learning disabilities, one child with PVL had specific non-verbal intelligence impairment, and the third child had non-ischaemic hydrocephalus with global mental re...

Introduction Intraventricular hemorrhage (IVH), a frequent complication in premature infants, is associated with parenchymal injury including white matter injury. Hypothesis: We hypothesized that the processes that cause IVH in premature babies would also result in white matter injury. Our objective was to investigate the effect of IVH on white matter injury as assessed by diffusion tensor imaging (DTI). Methods Premature infants, born at less than 32 weeks gestational age, underwent DTI MRI scans at 10-14 days of life and again at 37 weeks postconceptional age. Using T1, T2 and FLAIR images, patients were assigned into 2 groups: normal controls (n=12) or IVH group (total n=7: 4 with Grade I-II and one PVL, 3 with III-IV). Diffusion coefficient (ADC), fractional anisotropy (FA) and directional correlation (DC) were measured on multiple regions of interest. Results There was a decrease in FA and increase in ADC with age for white matter tracts; the opposite changes occurred for gray matter. Comparing the tw...

‘The NIH MRI Study of Normal Brain Development is being carried out by the 'Brain Development Cooperative Group' and is the most comprehensive and rigorous study of human brain and behavioral development ever conducted. For the Objective-2 part of the study, structural MR images, diffusion tensor MR, and MR spectroscopy are obtained at 3-6 month intervals from non-sedated, normally developing children from the ages of birth through 4.5 years. A 1.5 T scanner (Magnetom Sonata; Siemens) with circularly-polarized radiofrequency head coil was used. Protocol consisted of T1W, PDW/T2W, T1 relaxometry, diffusion tensor imaging (DTI) and dual contrast T2W. T1W (500.0/12.0 [repetition time msec/echo time msec]), PDW/T2W (3500.0/17.0 and 119 [repetition time msec/echo times msec]), T1 relaxometry (9990.0/46.7 [repetition time msec/echo time msec] with 0, 50, 400, 800, 1200 and 2000 [inversion times msec]), and double echo quantitative T2 (3500.0/83.0 and 165 [repetition time msec/echo times msec]) were acquired in o...

Previous neuroimaging studies of individuals with chronic stroke have frequently tested the morphological changes (e.g. white matter integrity/ volume) of corticospinal tract in the brain. However, white matter changes of corticospinal tract in spinal c...

The predisposition to engage in autonomous habitual behaviors has been associated with behavioral disorders such as obsessive-compulsive disorder and addiction. Attentional set-shifting tasks (ASSTs), that incorporate changes governing the association of discriminative stimuli with contingent reinforcement, are commonly used to measure underlying processes of cognitive/behavioral flexibility. The purpose of this study was to identify primate brain networks that mediate trait-like deficits in ASST performance using resting state functional magnetic resonance imaging (rsfMRI). A self-pacing ASST was administered to 3 cohorts of rhesus monkeys (total n=35, 18 female). Increased performance over 30 consecutive sessions segregated the monkeys into 2 populations, termed High Performers (HP, n=17) and Low Performers (LP, n=17), with one anomaly. Compared to LPs, HPs had higher rates of improving performance over sessions and completed the 8 sets/session with fewer errors. LP monkeys, on the other hand, spent most...

The KIBRA gene has been associated with episodic memory in several recent reports; carriers of the T-allele show enhanced episodic memory performance relative to noncarriers. Gene expression studies in human and rodent species show high levels of KIBRA in the hippocampus, particularly in the subfields. The goal of the present study was to determine whether the KIBRA C→T polymorphism is also associated with volume differences in the human hippocampus and whether specific subfields are differentially affected by KIBRA genotype. High-resolution magnetic resonance imaging (T2-weighted, voxel size = 0.4 × 0.4 mm, in-plane) was used to manually segment hippocampal cornu ammonis (CA) subfields, dentate gyrus (DG), and the subiculum as well as adjacent medial temporal lobe cortices in healthy carriers and noncarriers of the KIBRA T-allele (rs17070145). Overall, we found that T-carriers had a larger hippocampal volume relative to noncarriers. The structural differences observed were specific to the CA fields and DG...

The first in vivo magnetic resonance study of experimental cerebral malaria is presented. Cerebral involvement is a lethal complication of malaria. To explore the brain of susceptible mice infected with Plasmodium berghei ANKA, multimodal magnetic resonance techniques were applied (imaging, diffusion, perfusion, angiography, spectroscopy). They reveal vascular damage including blood-brain barrier disruption and hemorrhages attributable to inflammatory processes. We provide the first in vivo demonstration for blood-brain barrier breakdown in cerebral malaria. Major edema formation as well as reduced brain perfusion was detected and is accompanied by an ischemic metabolic profile with reduction of high-energy phosphates and elevated brain lactate. In addition, angiography supplies compelling evidence for major hemodynamics dysfunction. Actually, edema further worsens ischemia by compressing cerebral arteries, which subsequently leads to a collapse of the blood flow that ultimately represents the cause of dea...

The current study examined the development of frontostriatal circuitry involved in overriding a competing or well learned behavioral set in favor of a novel response mapping. Imaging studies of motor response learning, such as serial reaction time tasks, have implicated the insula cortex and basal ganglia regions in the learning of novel response patterns. Given the delay in maturation of prefrontal cortex and the basal ganglia, we predicted a developmental difference in performance on tasks involving stimulus-response conflict, presumably related to the developmental delay in organization of this circuitry. Using functional MRI, we compared the brain activation elicited during well-learned and novel stimulus-response mappings. Nine right handed adults (mean age=24.5 years, 3 females) and nine right handed children (mean age=8.8 years, 4 females) were scanned while performing the stimulus-response compatibility task. Echo planar images (TR = 6000, TE = 40, 128 X 64) were acquired in twenty-six 5 mm contigu...