Language function was studied in 17 patients with infarctions apparently confined to unilateral basal ganglia and surrounding white matter [10 left hemisphere (LH), 7 right hemisphere (RH)]. Mean age at injury was 7yrs and 4yrs, and mean age at study was 12yrs and 9yrs, for the LH and RH groups respectively. We have previously shown that long-term receptive and expressive language outcome did not differ significantly between the LH and RH groups. The variance in the LH group was, however, much greater than in the RH group. Voxel-based morphometric analyses of structural MRI 3D datasets and MR diffusion tensor imaging data identified regions of grey and white matter density and diffusion anisotropy, outside the site of the infarction and including Broca’s area, that correlated with language performance in the LH group but not in the RH group. Furthermore, the only 3 patients with haemodynamic abnormalities involving left cortical language areas on MR perfusion imaging were the 3 LH patients with poorest lan...

The distribution of myelin in the human brain provides a basis for the parcellation of cortex into distinct anatomical and functional subunits. in-vivo studies have shown that myeloarchitectural features such as the stria of Gennari can be found within primary visual cortex (Clark et al (1991), Barbiere et al (2002)) and that more subtle features can be detected in extrastriate cortex (Walters et al (2003). Analysis of this data usually requires time-consuming manual study to determine the boundaries between white matter and gray matter and to carry out densitometric analysis. Accurate cortical surfaces allow line density profiles to be automatically and objectively generated and analyzed. Here we present an early example of this technique on high resolution MR images acquired using an MP-RAGE sequence with occipital or flexible bi-temporal phased-array (Nova Medical). Voxel size was approximately 0.3 x 0.3 mm in plane with a slice thickness of 0.5mm-0.9mm. Cortical surfaces were computed using FreeSurfer ...

The corpus callosum (CC) comprises axons connecting the cortices of the two cerebral hemispheres and is the principal white matter fiber bundle in the brain. As recently as the mid 20th century, the CC was thought to serve no other purpose than preventing the two hemispheres from collapsing on one

Spinal cord injury (SCI) severity and recovery are influenced by complex pathological mechanisms, including demyelination/remyelination, glutamate excitotoxicity, scar formation, and inflammatory responses. The overall goal of this study is to develop a...

The quantitative distribution of gray and white matter in the human brain is not well established. Recent MRI-based studies have provided gray-white (G/W) measurements over large sectors of the brain, or have been based on sampling methods over smaller and arbitrarily defined regions. We report on a study of the gray-white volumes of the major lobes and gyri of the human cerebrum. Regions of interest were identified using neuroanatomical surface landmarks on 3D reconstructions of T1-weighted contiguous MR coronal slices through the whole brain (1.5-1.6mm thick; 110-120 slices per brain). The following lobes were manually traced separately for left and right hemispheres: frontal, parietal, temporal, occipital. Gyri traced included the cingulate, insula, and all the major gyri of the frontal, parietal, and temporal lobes. The MRI data were segmented into gray-white-CSF using an automated algorithm, which was capable of generating fractionally classified voxels. Subjects were 23 men (22-49 years, mean=32.1, s...

The importance of the basal ganglia in controlling motor function is well known. However, neuroimaging studies have failed to show either movement-rate dependence or different activation patterns caused by self-initiated (SI) and externally triggered (ET) movements in the basal ganglia–thalamo-motor loop. We herein report the functional magnetic resonance image (fMRI) mapping of sequential left-hand finger movements at five different rates under SI and ET conditions. Significant movement-rate dependence was found in the whole right basal ganglia–thalamo-motor loop only during the SI task. Network analysis also showed strong interactions within this loop during SI movement, whereas interactions were present only from the premotor cortex to the putamen via the sensorimotor cortex during the ET task. Furthermore, psychophysiological interaction analysis confirmed the different modulation between the two tasks in the putamen. fMRI provides evidence that the basal ganglia–thalamo-motor loop plays a key role in ...

Previous functional neuroimaging studies have not determined cortical areas of selective somatosensory processing of stimulus attributes or location. To address this, we studied 20 subjects trained in two tactile tasks. For both tasks, a set of domes with gratings was used. Gratings were delivered to the immobilized finger. For each trial, a grating was first applied distally with the bars/grooves parallel to the long axis of the finger. Subjects were either required to judge if the grating orientation (GOT) or stimulation site (location task (LOT) changed during a 2nd presentation. Subjects attended to either orientation or location while activations were measured using block design fMRI at 3T. Group performance was very similar for the GOT (74% correct responses) and LOT (74%). Similar activations for both tasks were seen in the primary and secondary somatosensory cortices. The intraparietal sulcus (IPS) was preferentially activated bilaterally in most subjects during the GOT. However, there were signifi...

The capacity to attend to task demands while viewing nontask-related emotional stimuli undergoes profound development during adolescence. However, researchers are only beginning to explore neurobiological correlates of this cognitive process. In the present investigation, 17 adolescents (9-17 years of age) and 17 adults (25-36 years of age) were scanned using event-related fMRI at 3T. Subjects viewed neutral and emotional faces (angry, fearful and happy) passively and also while attending to emotional and physical features. In the initial analysis, three main results emerged. (1) Adolescents showed greater amygdala and prefrontal cortex activation than adults during passive viewing of angry vs. neutral faces. (2) Both adults and adolescents engaged ventral lateral and dorsal prefrontal regions while attending to internal fear state during angry vs neutral face viewing. (3) Greater discriminant activation emerged in adults vs. adolescents within the contrast of internal fear rating to angry faces vs. physic...

The anterior limb of the internal capsule (ALIC) carries thalamic and brainstem fibers from prefrontal cortical regions that are associated with different aspects of emotion, motivation, cognition processing, and decision-making. This large fiber bundle is abnormal in several psychiatric illnesses and a major target for deep brain stimulation. Yet, we have very little information about where specific prefrontal fibers travel within the bundle. Using a combination of tracing studies and diffusion MRI in male nonhuman primates, as well as diffusion MRI in male and female human subjects, we segmented the human ALIC into five regions based on the positions of axons from different cortical regions within the capsule. Fractional anisotropy (FA) abnormalities in patients with bipolar disorder were detected when FA was averaged in the ALIC segment that carries ventrolateral prefrontal cortical connections. Together, the results set the stage for linking abnormalities within the ALIC to specific connections and dem...

Older adults have reduced memory, primarily for recall, but also for recognition ([Craik and McDowd, 1987][1]), particularly for unfamiliar faces ([Bartlett et al., 1989][2]). Behavioral studies have shown that age-related memory declines are due in part to distraction from impaired inhibition of task-irrelevant input during encoding ([Healey et al., 2008][3]). Functional magnetic resonance imaging (fMRI) has been used to uncover the sources of memory deficits associated with aging. To date, this work has focused on successful encoding, while the neural correlates of unsuccessful encoding are unknown. Here, we provide novel evidence of a neural mechanism underlying memory failures exclusively affecting older adults. Whereas both younger and older adults showed reduced activation of brain regions important for encoding (e.g., hippocampus) during unsuccessful encoding, only older adults showed increased activity in brain regions mediating distraction (e.g., auditory cortex) and in left prefrontal cortex. Fur...