Background Autism spectrum disorder (ASD) is characterized by social and behavioral impairments. Although it is a neurodevelopmental disorder, no unique brain biomarkers for ASD are known. Previous research has used machine learning and computational st...

Determination of stroke volume is an important parameter to be taken into consideration while evaluating behavioral performance during ongoing experiments, such as those in rodent models. The methods we describe below would allow for the quantification ...

Rhesus monkeys undergo cognitive decline as a function of age, which correlates with the breakdown of axonal myelin. Whether the myelin breakdown is diffuse or specific to individual white matter fiber pathways remains to be clarified. In the present study we investigated the changes in the cingulum bundle using DT-MRI in young (Group 1, N=5), middle-aged (Group 2, N=2), and old (Group 3, N=6) monkeys. METHOD: MRI scanning was performed using a Siemens Sonata 1.5T. Scans included sagittal MP-RAGE pulse sequences and echo-planar DT-MRI. The diffusion tensor, D, was sampled using a seven-shot EPI technique with the following parameters: TR=130ms, TE=80ms, 96 averages, voxel size=1.3x1.3x2.0mm3, b=600s/mm2, 40 contiguous coronal slices for a total acquisition time=66 minutes and SNR=100. RESULTS: The average total cingulum bundle volumes were 0.60cm3 (SD=0.19) in Group 1, 0.75cm3 (SD=0.19) in Group 2, and 0.49cm3 (SD=0.28) in Group 3. The average total cingulum bundle fractional anisotropy (FA) values were 0....

Diffusion MRI (dMRI) microstructure techniques, e.g. axon diameter and membrane permeability estimation, are often validated using Monte Carlo (MC) simulations. The geometric substrates are usually oversimplified cylindrical models. This work investigat...

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...

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...

Objective To evaluate the reliability of MRI diffusion tensor tracking (DTT) of the amygdalo-calcarine pathway and for general neuroscience studies. Introduction DTT provides a means to assess white matter (WM) connections in living humans by tracing water diffusion. To use DTT, it is important to know its reliability. Methods We quantified vector distance errors by numerical simulation of the DTT procedures for an analytical curved pathway. We also assessed experimental reproducibility across subjects. Results Errors in track location at 6cm were 0.04±0.08mm (N=30) for standard conditions. The variance V of the error distance was proportional to track length L for almost all experimental conditions, with α=V/L strongly dependent on SNR, number of averages, and WM anisotropy. To gauge reproducibility, the amygdalo-calcarine tract involved in emotional modulation of visual perception was replicated across subjects, including a tight curve at the amygdala (arrows in Figure). Conclusion DTT errors have a pred...

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...