Biomedical subjects

Peggy Nopoulos

Publications and source records attributed to Peggy Nopoulos.

7 recordsLinked to original sources

PubMed2006

Anterior cingulate cortex: an MRI-based parcellation method.

OBJECTIVE: The anterior cingulate cortex (ACC) is an important part of the limbic system involved in emotions, cognition and executive function. The ACC has structurally distinct subregions, both microscopically and functionally, that have been implicated in several major psychiatric disorders. However, a structural analysis of these subregions with magnetic resonance imaging (MRI) has not been done. Our main purpose was to develop an MRI-based parcellation method of the ACC that permits us to explore plausible abnormalities in 4 functionally relevant subregions: dorsal, rostral, subcallosal and subgenual. METHODS: The reliability study for gray matter volume and surface area of each subregion was performed on 14 randomly selected MR scans by 3 different raters. Our method posits to conserve the topographic uniqueness of individual brains and is based on our ability to visualize both the 3-dimensional rendered brain and the 3 orthogonal planes simultaneously with BRAINS2 software. We developed rules to hand-trace regions of interest (ROI) to surround contiguous areas of gray matter for dorsal, rostral, subcallosal and subgenual regions. The ACC was then parcellated into these 4 distinct subregions (8 when both right and left hemispheres were measured). RESULTS AND DISCUSSION: The intraclass R coefficients for gray matter volume of each subregion ranged between 0.85 and 0.93. The current study describes a new highly reliable and reproducible topography-based parcellation method of the ACC into its dorsal, rostral, subcallosal and subgenual regions. CONCLUSIONS: This new parcellation method provides a new means of exploring the role of the functionally and structurally distinct subregions of the ACC in schizophrenia, depression and various other brain illnesses.

Cerebral Cortex↗

PubMed2006

Perception of socially relevant stimuli in schizophrenia.

To examine whether patients with schizophrenia have deficits in the appraisal of socially relevant stimuli, we tested 20 patients and 14 healthy volunteers equated for parental socioeconomic status on recognition of gender stimuli, emotional people stimuli, and emotional scenes. Patients with schizophrenia showed deficits in discrimination of subtle gender differences and in the identification of emotion from human shapes and body motion. Patients showed no impairment on measures of hedonic appraisal of emotional scenes and recognition of emotional expression in human face stimuli. Across tasks, subjects with schizophrenia showed poorer identification of happiness, anger, and fear. The findings point towards circumscribed domains of impaired social cognition in schizophrenia and suggest specific further hypotheses about the neural dysfunction that may underlie them.

Adult↗

PubMed2003

Initial magnetic resonance imaging volumetric brain measurements and outcome in schizophrenia: a prospective longitudinal study with 5-year follow-up.

BACKGROUND: Several demographic and phenomenological variables have been identified as predictors of outcome in schizophrenia. Far fewer studies have examined the relationships between brain morphology assessed at illness onset and subsequent outcome, and their results have been contradictory. METHODS: The relationships between magnetic resonance imaging (MRI) regional brain volumes at illness onset and outcome five years later were studied in 123 schizophrenia patients using regression and correlation analysis. Outcome measures included psychosocial functioning, weeks per year receiving inpatient treatment, and persistence of severe psychotic, disorganized and negative symptoms. RESULTS: Temporal lobe tissue volume at onset was predictive of outcome. Smaller temporal lobe gray matter volume (both left and right) was associated with persistence of hallucinations during follow-up. There were no significant associations between hallucinations and temporal white matter, or between delusions and temporal white or gray matter volumes. None of the other volumetric brain measures were predictive of outcome. CONCLUSIONS: The association between initial temporal lobe gray matter volume and subsequent persistent hallucinations may help identify individuals who are at higher risk for poor outcome and help guide their treatment planning. However, regional brain volumes assessed near illness onset, in general, do not appear to be indicative of subsequent outcome in schizophrenia.

Age of Onset↗

PubMed2003

Gyrification abnormalities in childhood- and adolescent-onset schizophrenia.

BACKGROUND: Gyrification is an important index of brain development. We used magnetic resonance scanning technology to compare brain surface morphology and measures of gyrification in children and adolescents with a schizophrenia spectrum disorder and in age-equivalent healthy controls. METHODS: Magnetic resonance scans were obtained from 42 patients and 24 healthy controls, mean age 17.7 years for both groups. We employed novel quantitative measures of brain morphology, including cortical thickness and a variety of indices of sulcal and gyral curvature. We examined these measures in the whole brain and in the frontal, temporal, parietal, and occipital lobes. RESULTS: There were significant decreases in cortical thickness in the patients. This was most pronounced in the cortical tissue that underlies the sulci. The patient group had significantly more flattened curvature in the sulci and more steeped or peaked curvature in the gyri. CONCLUSIONS: This study quantitatively examines cortical thickness and surface morphology in children and adolescents with schizophrenia. Patients with schizophrenia demonstrated patterns of brain morphology that were distinctly different from healthy controls. In light of current theories of the formation of gyri and sulci, these changes may reflect aberrations in cerebral and subcortical connectivity.

Adolescent↗

PubMed2003

NOTCH4 and the frontal lobe in schizophrenia.

NOTCH4 is a developmentally expressed gene recently reported to be in linkage disequilibrium (LD) with schizophrenia. We investigated this finding in our sample of subjects, focusing on an exonic (CTG)(n) polymorphism, examining not only the association of this polymorphism with the disease phenotype, but also its effect on frontal lobe brain morphology and cognitive function in both affected individuals and a psychiatrically normal comparison group. While we did not find any association or LD with schizophrenia, we identified striking effects of NOTCH4 variability on the trait measures. Within the respective schizophrenia and comparison groups, NOTCH4 allelic variability was correlated with differences in measures of frontal lobe cognitive performance and frontal lobe brain tissue volumes that were intuitively congruent. These within-group effects, however, were in opposite directions across groups. These findings may reflect the interaction of NOTCH4 with the underlying genetic and phenotypic complexity that characterizes both schizophrenia and normal cognition and brain development.

Adult↗

PubMed2002

Brain volumes and surface morphology in monozygotic twins.

Because healthy monozygotic twins share an identical genetic complement, they provide a unique opportunity to explore the genetic and environmental determinants of brain development. The purpose of this study was to evaluate the similarities between measures of cerebral and subcortical volumes and surface morphology in monozygotic twins compared with a matched control sample. Combinations of automated and manual methods were used to evaluate total brain volume, gray matter, white matter, ventricles and volumes of the frontal, temporal, parietal and occipital lobes. An artificial neural network algorithm was used to measure the cerebellum, thalamus, caudate and putamen. Measures of surface morphology included an index of gyral and sulcal curvature, surface area and cortical depth. The cerebral volume regions, including the gray matter, white matter and lobar volumes, were highly correlated within monozygotic twin pairs, with nearly all correlation coefficients >0.90. The cerebellum was also highly correlated (r = 0.99). Reasonably high correlations were found for the cortical depth (r = 0.84), caudate (r = 0.84), thalamus (r = 0.75) and putamen (r = 0.75). The surface measures, however, demonstrated the least correlation within twin pairs and thus are more prone to environmental influences. The high to moderate correlations between MZ twins compared with the matched controls highlights the role of heredity in both prenatal and postnatal neurodevelopment.

Adolescent↗

PubMed2002

Manual and automated measurement of the whole thalamus and mediodorsal nucleus using magnetic resonance imaging.

The thalamus is an important relay structure in the brain that may be relevant to a variety of brain diseases. It is divided into multiple subnuclei with different cortical connections. The medial dorsal (MD) nucleus is particularly important because it forms key connections with the prefrontal cortex. The current study reports precise and efficient methods for measuring the whole thalamus and the MD with MRI that have a high degree of interrater reliability. A multispectral image acquisition and novel image processing technique were used to improve structure visibility. The tricolor image assigns a color to each of the T1, T2, and PD weighted images, represented by red, green, and blue, respectively. The manually defined regions were then used to train an artificial neural network (ANN) to automatically define both the whole thalamus and the MD. The ANN provides an efficient automated method, making studies using larger sample sizes more feasible.

Aged↗