Biomedical subjects

Jay J Pillai

Publications and source records attributed to Jay J Pillai.

7 recordsLinked to original sources

PubMed2004

Neural substrates of emotion as revealed by functional magnetic resonance imaging.

OBJECTIVES: To examine the brain circuitry involved in emotional experience and determine whether the cerebral hemispheres are specialized for positive and negative emotional experience. BACKGROUND: Recent research has provided a preliminary sketch of the neurologic underpinnings of emotional processing involving specialized contributions of limbic and cortical brain regions. Electrophysiologic, functional imaging, and Wada test data have suggested positive, approach-related emotions are associated with left cerebral hemisphere regions, whereas negative, withdrawal-related emotions appear to be more aligned with right hemisphere mechanisms. METHOD: These emotional-neural associations were investigated using functional magnetic resonance imaging in 10 healthy controls with 20 positively and 20 negatively valenced pictures from the International Affective Picture System in a counterbalanced order. Pictures were viewed within a 1.5 Telsa scanner through computerized video goggles. RESULTS: Emotional pictures resulted in significantly increased blood flow bilaterally in the mesial frontal lobe/anterior cingulate gyrus, dorsolateral frontal lobe, amygdala/anterior temporal regions, and cerebellum. Negative emotional pictures resulted in greater activation of the right hemisphere, and positive pictures caused greater activation of the left hemisphere. CONCLUSIONS: Results are consistent with theories emphasizing the importance of circuitry linking subcortical structures with mesial temporal, anterior cingulate, and frontal lobe regions in emotion and with the valence model of emotion that posits lateralized cerebral specialization for positive and negative emotional experience.

Adult↗

PubMed2004

Functional MR imaging study of language-related differences in bilingual cerebellar activation.

BACKGROUND AND PURPOSE: Reports in the monolingual literature suggest that the cerebellum has an important role in language processing. The purpose of this study was to determine whether bilingual cerebellar functional MR imaging (fMRI) activation differs during the performance of comparable tasks in subjects' primary and secondary languages. METHODS: Eight bilingual, right-handed individuals underwent echo-planar fMRI at 1.5 T. They performed semantic (noun-verb association) and phonological (rhyming) tasks in Spanish (primary language) and English (secondary language). Individual and group functional datasets were analyzed using Statistical Parametric Mapping software (SPM99; P <.001 with a 10-voxel spatial extent threshold) and overlaid on T1-weighted anatomic images normalized to a standard (Montreal Neurologic Institute) space. Analysis of variance was performed on laterality indices derived from voxel counts in cerebellar regions of interest (ROIs). Subtraction of group-averaged normalized results from the combined Spanish tasks from the combined English tasks was also performed within SPM99 (P <.001 activation threshold). RESULTS: Significantly greater lateralilty indices were noted in the English tasks than in the Spanish tasks (mean Spanish LI, 0.3286; mean English LI, 0.5141 [P =.0143]). Overall, more robust activation was seen in the English tasks than in the Spanish tasks. Areas of significantly greater activation existed in the English tasks as compared with the Spanish tasks; these areas were more prominent in the left cerebellar hemisphere. CONCLUSION: Although both English and Spanish language tasks demonstrate left cerebellar dominance, English tasks demonstrate greater left hemispheric lateralization.

Adult↗

PubMed2003

Functional MRI study of semantic and phonological language processing in bilingual subjects: preliminary findings.

The objective of the study was to explore differences in regional fMRI activation topography and lateralization between semantic and phonological tasks performed in English and Spanish in bilingual individuals. Eight bilingual (primary Spanish and secondary English-speaking) individuals performed fMRI noun-verb association and rhyming tasks in both Spanish and English. Functional dataset analysis within Statistical Parametric Mapping (SPM99) with overlay on T1-weighted anatomic images was performed. Significantly higher laterality indices were noted in the semantic tasks as compared with the phonological tasks in the anterior regions of interest comprising the frontal and superior temporal lobes. A task subtraction analysis demonstrated right hemispheric (inferior frontal gyrus and supramarginal gyrus) foci of significantly increased activation in the combined language phonological tasks compared to the combined language semantic tasks; similarly prominent right hemispheric activation was seen in the English phonological-English semantic subtraction, but the analogous Spanish task subtraction revealed no task-related differences. This divergence in activation topography between semantic and phonological tasks performed in the nonnative language, but not in the primary language, suggests that neural networks utilized for phonological and semantic language processing in the nonnative language may not be as similar as those in the primary language.

Adult↗

PubMed2003

Sustained spinal cord compression: part I: time-dependent effect on long-term pathophysiology.

BACKGROUND: The objective of this study is to determine whether there is a relationship between the duration of sustained spinal cord compression and the extent of spinal cord injury and the capacity for functional recovery after decompression. METHODS: Sixteen dogs underwent sustained spinal cord compression for thirty or 180 minutes. The cords were compressed with use of a loading device with a hydraulic piston. A pressure transducer was attached to the surface of the piston, which transmitted real-time spinal cord interface pressures to a data-acquisition system. Somatosensory evoked potentials were monitored during a sixty-minute recovery period as well as at twenty-eight days after the injury. Functional motor recovery was judged throughout a twenty-six-day period after the injury with use of a battery of motor tasks. The volume of the lesion and damage to the tissue were assessed with both magnetic resonance imaging and histological analysis. RESULTS: Sustained spinal cord compression was associated with a gradual decline in interface pressure. Despite this, there was continuous decline in the amplitude of the somatosensory evoked potentials, which did not return until the cord was decompressed. Within one hour after the decompression, the dogs in the thirty-minute-compression group had recovery of somatosensory evoked potentials, but no animal had such recovery in the 180-minute group. Recovery of the somatosensory evoked potentials in the thirty-minute group was sustained over the twenty-eight days after the injury. Motor tests demonstrated rapid recovery of hindlimb motor function in the thirty-minute group, but there was considerable impairment in the 180-minute group. Within two weeks after the injury, balance, cadence, stair-climbing, and the ability to walk up an inclined plane were significantly better in the thirty-minute group than in the 180-minute group. The longer duration of compression produced lesions of significantly greater volume, which corresponded to the long-term functional outcome. CONCLUSIONS: The relatively rapid viscoelastic relaxation of the spinal cord during the early phase of sustained cord compression suggests that there are mechanisms of secondary injury that are linked to tissue displacement. Longer periods of displacement allow propagation of the secondary injury process, resulting in a lack of recovery of somatosensory evoked potentials, limited functional recovery, and more extensive tissue damage.

Animals↗

PubMed2002

Increased presence of white matter hyperintensities in adolescent patients with bipolar disorder.

Several reports have noted an increase in white matter hyperintensities (WMH) on MRI scans of adult patients with bipolar disorder. We investigated whether this increase was also evident in a group of adolescent patients with bipolar disorder. The sample consisted of 15 bipolar patients, 19 patients with schizophrenia and 16 healthy comparison subjects. All subjects were adolescents. WMH were blindly rated on T2-weighted and PD-weighted MRI scans using our own scale with documented inter-rater reliability. WMH were present in 10 of 15 bipolar patients (67%), seven of 19 patients with schizophrenia (37%) and five of 16 comparison subjects (31%). The bipolar adolescent group had a statistically significant increased presence of WMH compared both with healthy comparison subjects and the schizophrenic group. The association between WMH and bipolar disorder appears to extend to the adolescent years.

Adolescent↗

PubMed2002

A longitudinal MRI study in children with Rasmussen syndrome.

The aim of this study was to identify the presence of any neuroimaging patterns of Rasmussen syndrome using magnetic resonance imaging (MRI). This was a prospective study evaluating brain MRIs in seven children with neuropathologically proven Rasmussen syndrome. All patients were unresponsive to conventional antiepileptics; five patients subsequently underwent functional hemispherectomy, and two patients underwent cortical resection. Three to eight (mean = 4.7) MRIs per patient were performed, and neuropathologic examination of the brain was available. Serial MRIs were obtained between 12 months before and 9 months after the onset of epilepsia partialis continua. The most common region of initial MRI signal change was the frontocentral region (six patients). Three patterns of neuroimaging abnormalities were observed as follows: (1) normal MRI followed by increased signal intensity with progressive cortical atrophy over time, (2) initial increased focal signal intensity followed by decrease in spatial extent and degree of signal intensity; (3) initially increased signal intensity without further changes on follow-up scans. This observation suggests three possible distinct patterns of MRI changes in patients with Rasmussen syndrome and that the differences in these neuroimaging patterns may reflect inherent differences in the pathogenesis of Rasmussen syndrome.

Adolescent↗

PubMedDate not supplied

Advanced MR imaging of cortical dysplasia with or without neoplasm: a report of two cases.

We herein describe two cases of patients with epilepsy with occipital lobe cortical dysplasia who were studied with both MR spectroscopy and MR diffusion imaging in addition to conventional MR imaging. Greater diffusion abnormalities, as well as more marked decreases in N-acetylaspartate, were observed to occur in the patient harboring a low grade neoplasm within an area of cortical dysplasia than in the patient with cortical dysplasia alone.

Adult↗