Traumatic brain injury (TBI) is the most common cause of acquired disability in children and adolescents. TBI has a devastating impact on white matter (WM) tracts and can disrupt ongoing brain development. Previous studies in children with moderate-to-s...

Thickness of the cerebral cortex was measured in 88 healthy nondemented volunteers with an age range of 48–75 years (Mean=65). 56 participants were classified as APOE ε4- (no ε4 allele) and 32 as ε4+ (1 or 2 ε4 alleles). The genotype groups had similar age, sex (72/28% f/m) and IQ (Mean/SD=117/11). Two T1-weighted MP-RAGE sequences were averaged for each participant to yield images with high signal-to-noise ratio. Images were analyzed semi-automatically as described by Salat et al (2004). We first analyzed general age effects in all 88 participants. Preliminary results indicate significant global white matter volume loss with increasing age whereas gray matter loss showed a similar, but non-significant trend. Regionally specific cortical thinning was evident with increasing age, especially in occipital areas, insula, parts of the temporal lobes, central sulcus, precentral gyrus and a subset of prefrontal areas. The sample’s age range precludes any direct comparison with previous research but the results ar...

This study examined the relation of fronto-limbic functional abnormalities to particular components of PTSD symptomology, in this case the symptoms of psychological and physiological distress. Subjects with DSM-IV diagnosis of PTSD, associated with sexual/physical assault, were studied using two complementary fMRI activation probes, an emotional word paradigm, and an instructed fear conditioning paradigm. Symptoms were evaluated by the Clinician-Administered PTSD Scale (CAPS). Significant activations at p<0.05 (SVC) in a priori regions of interest are reported. As expected, activity changes in mesotemporal and ventro-medial prefrontal brain regions correlated more closely with the relevant combinations of probes and clinical symptoms. With the linguistic, top-down emotional word paradigm, the CAPS score for psychological distress (B4) was positively correlated with right more than left amygdala activity, and negatively with left posterior OFC, left ventral striatum and anterior insula activity. With the no...

Accumulating evidence indicates that motor execution and imagery substantially share the underlying neural substrates, but the extent of overlap is still under debate. To clarify this issue further from the viewpoint of effector specificity or somatotopy of the motor system, we performed a functional MRI experiment in 4 healthy right-handed volunteers. On a 3-T MRI scanner, the subjects performed actual and imaginary sequential tapping guided by a series of visual number stimuli presented at 0.6 Hz. An experimental session consisted of eight 30-s task blocks (semi-randomized for execution and imagery blocks) alternated with baseline fixation periods. Task performance of both movement and imagery tasks was checked at the end of each task period through responses from the subjects. Two fMRI sessions were conducted separately for each hand. Echoplanar images (TR = 3 s) were acquired with prospective acquisition correction. Statistical parametric mapping revealed brain areas more activated during the right han...

The Research Domain Criteria (RDoC) project aims to be complementary to the Diagnostic and Statistical Manual of Mental Disorders (DSM), by redefining boundaries among psychiatric disorders. One of their most influential works is the study by Clementz e...

Visual perceptual learning is often specific for the region of the visual field where training is carried out, suggesting that learning-related plasticity occurs at a level of the visual cortical hierarchy where receptive fields are small. In an ongoing fMRI study, we are investigating the neural correlates of perceptual learning in a visual hyperacuity task. Subjects reported the direction of lateral offset of the center dot of a linear, vertically oriented, 3-dot array, presented at 5 degrees of eccentricity in the lower left quadrant of the visual field. Psychophysical thresholds were expressed in terms of the magnitude of offset required for 75% correct discrimination. This threshold declined over a number of training sessions (~10). fMRI data and high-resolution anatomic scans were acquired during pre-training and post-training sessions using a Siemens 3T scanner, and analyzed using BrainVoyager QX. A block design was used for fMRI data acquisition, with alternating active and fixation blocks, each of...

The aim of study was to identify potential mechanisms of neurodegeneration by correlating image analysis of brain structures and immunocytochemical analysis of cholinergic pathways. The study was performed in transgenic mice that overexpress either normal human APP (amyloid precursor protein) or SOD1 (superoxyde dismutase 1) or a combination of both genes. Neuropathological studies were performed with T2 magnetic resonance imaging. Multislice axial and sagittal sequences were acquired in a Brucker Biospec (7 Tesla) with spin-echo imaging (TE 65ms, slice thickness 0.40 mm, data matrix 192x128). Following image analysis of these sequences, 3D construct of various brain structures were performed. Statistical comparison of brain regions volumes was performed between various mice. As nitric oxide (NO) may affect cholinergic neurons development, we investigated the morphology of neurons expressing ChAT or NADPH-diaphorase in the brain of transgenic mice. Heavily stained neurons were found in cholinergic regions ...

High cardiovascular reactivity due to stress has been established as a risk factor for the development of cardiovascular disease. Animal and human studies indicate a role of forebrain regions, specifically the medial prefrontal cortex, the insular cortex and the amygdala, in mediating autonomic control of the cardiovascular system. However, the specific regions of the forebrain involved in the cardiovascular control during the stress response in humans are unknown. The purpose of this study is to investigate what proportion of a young healthy population demonstrates cardiovascular reactivity to a laboratory mental stress task, and to determine the forebrain regions involved in the stress response in high cardiovascular reactors (reactors) and low cardiovascular reactors (non reactors). Methods: In a prescreening trial, 50 volunteer subjects (mean age 24) performed 2 mental stress tasks: mental arithmetic (MA) and the Stroop Color Word Task (SCWT). Heart rate (HR) and Mean Arterial Pressure (MAP) were conti...

Introduction: Parcellation of the cerebellar cortex allows for detailed functional and structural imaging studies of the cerebellum. Volumetric changes during normal development and aging, or related to pathology, emphasize the relevance of morphometric analysis of cerebellar cortex. Previously, we described a parcellation system of the human cerebellar cortex based upon neuroanatomy [1]. In the present study morphometric analysis was performed on five normal humans, as well as intra- and inter-rater reliability measurements. Methods: The cerebellar cortex of five normal human subjects was parcellated using T1-weighted anatomic MR images. The method of parcellation applied here was based on our previous study, which delineated 20 parcellation units (PUs) in each cerebellar hemisphere and 12 PUs in each hemivermis [1]. Reliability measurements were performed on the resulting parcellations. Results and Discussion: Volumetric analysis and trials for intra- and inter-rater reliability were performed in a blind...

Diffusion tensor tracking (DTT) using MRI provides a means of visualizing neuronal fiber pathways not typically seen on conventional MRI or other modalities. Thus, DTT may provide a unique means of identifying the specific pathways involved by focal lesions within homogeneous-appearing white matter (WM). We used DTT in normal subjects to locate different visual pathways within occipital WM. Using DTT as a guide, subtle contrast differences within WM were identified on T2 weighted imaging (T2WI) that corresponded to the geniculocalcarine tract. We then used DTT to analyze the location of focal WM lesions near the cingulum. In one patient the cingulum was traced by DTT and coursed immediately medial to the lesion, ruling out cingulum involvement. DTT retrospectively identified subtle T2 contrast in homogeneous-appearing WM that had the morphology of the cingulum. In a second patient, a focal lesion near the cingulum mirrored the shape of the contralateral cingulum based on T2WI contrast, and the lesion obscu...