To elucidate cortical mechanisms of visuomotor integration, we recorded whole-scalp neuromagnetic signals from six normal volunteers while they were viewing a black dot moving linearly at the speed of 4°/sec within a virtual rectangle. The dot changed its direction randomly once every 0.3–2 sec. The subject either (1) fixated a cross in the center of the screen (eye fixation task), (2) followed the moving dot with the eyes (eye pursuit task), or (3) followed the dot with both the eyes and the right index finger (eye–finger pursuit task). Prominent magnetic signals, triggered by the changes of the direction of the dot, were seen in all conditions, but they were clearly enhanced by the tasks and were strongest during the eye–finger pursuit task and over the anterior inferior parietal lobule (aIPL). Source modeling indicated activation of aIPL [Brodmann’s area (BA) 40], the posterosuperior parietal lobule (SPL; BA 7), the dorsolateral frontal cortex (DLF; BA 6), and the occipital cortex (BA 18/19). The activa...

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...

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...

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). MRI is extensively used for non-invasive diagnosis and monitoring progression of MS pathology in the CNS. The cuprizone-rapamycin (CR) mouse model of M...

Little is known about how the properties of our private mental world relate to the physical and functional properties of our brain. Studying synesthesia, where a particular experience evokes a separate additional sensory experience, offers the unique opportunity to study phenomenological experiences as a stable trait in healthy subjects. A common form of synesthesia is grapheme–color synesthesia, where a particular letter or number evokes a particular color experience. We studied the neural basis of qualitative different properties of the synesthetic experience by using individual differences in grapheme–color synesthesia. Specifically, the synesthetic color can be experienced “in the mind” (associator synesthetes) or “in the outside world” (projector synesthetes). Gray matter structure and functioning (imaged using voxel-based morphometry and functional magnetic resonance imaging, respectively) were examined in grapheme–color synesthetes ( N = 42, 16 projectors and 26 associators) and nonsynesthetes. Resu...

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 ...

We used MRI to investigate the effect of normal aging on the volume of selected brain structures in seven young (5-10 yrs.), five middle-aged (11-20 yrs.) and eight old (21-30 yrs.) monkeys (macacca mulatta). A 1.5T Signa GE scanner acquired coronal proton density- and T2-weighted images using two interleaved dual-echo spin-echo sequences [TR=3000ms; TE=30/80ms; 2.7mm slc, FOV=150mm (256 x 256), 1 nex]. The images were filtered to improve signal-to-noise, then the intra-cranial cavity (ICC) was segmented under visual guidance. Voxels within the ICC were classified and grouped into 11 structures of interest using automated statistical Expectation-Maximization (EM), and Spatially Varying Classification (SVC) segmentation algorithms adapted for monkey MRI analysis. One-way ANOVA revealed an overall significant effect of age group on the volume of forebrain white matter [F(2,17)=4.53, p=0.03]. A posteriori comparisons showed a significant reduction of forebrain white matter volume in the old-aged monkeys when ...

Quantitative MRI techniques provide a good tool for studying brain-behavior relations in vivo. In this study, we examined the relation between performance in 2 memory tasks and the volumes of given brain regions in 44 elderly participants; 25 were diagnosed with mild cognitive impairment and 19 had no cognitive impairment. Each subject underwent a high resolution MRI scan and was examined with 1) verbal and spatial versions of the Buschke controlled learning task (BCL); 2) self ordered pointing task (SOP) that assesses working memory. Volumes of the hippocampal formation (HF) and entorhinal cortex (EC) were derived from 1.6 mm gapless coronal slices taken perpendicular to the long axis of the HF, while the cingulate gyrus (CG) was segmented from images taken perpendicular to the AC-PC line. To correct for individual differences in brain size, volumes of regions of interest (ROI) were divided by total intracranial volume. Regression analyses using HF, EC, anterior and posterior CG volumes showed a task x RO...