Biomedical subjects

Y C Vauss

Publications and source records attributed to Y C Vauss.

6 recordsLinked to original sources

PubMed1997

Implication of right frontostriatal circuitry in response inhibition and attention-deficit/hyperactivity disorder.

OBJECTIVE: To examine the relation between specific frontostriatal structures (prefrontal cortex and basal ganglia) and response inhibition deficits observed in attention-deficit/hyperactivity disorder (ADHD). METHOD: Children with ADHD and age-matched normal controls were scanned using magnetic resonance imaging (MRI) and tested on three response inhibition tasks. Behavioral performance was correlated with MRI-based anatomical measures of frontostriatal circuitry (prefrontal cortex and basal ganglia) implicated in ADHD. RESULTS: First, significant differences in performance by children with ADHD and normal volunteers were observed on all three response inhibition tasks. Second, performance on these tasks correlated only with those anatomical measures of frontostriatal circuitry observed to be abnormal in children with ADHD (e.g., the region of the prefrontal cortex, caudate, and globus pallidus, but not the putamen) in the authors' previous study. Third, significant correlations between task performance and anatomical measures of the prefrontal cortex and caudate nuclei were predominantly in the right hemisphere, supporting a role of right frontostriatal circuitry in response inhibition and ADHD. CONCLUSION: The data suggest a role of the right prefrontal cortex in suppressing responses to salient, but otherwise irrelevant events while the basal ganglia appear to be involved in executing these behavioral responses.

Adolescent↗

PubMed1996

Quantitative MRI of the temporal lobe, amygdala, and hippocampus in normal human development: ages 4-18 years.

The volume of the temporal lobe, superior temporal gyrus, amygdala, and hippocampus was quantified from magnetic images of the brains of 99 healthy children and adolescents aged 4-18 years. Variability in volume was high for all structures examined. When adjusted for a 9% larger total cerebral volume in males, there were no significant volume differences between sexes. However, sex-specific maturational changes were noted in the volumes of medial temporal structures, with the left amygdala increasing significantly only in males and with the right hippocampus increasing significantly only in females. Right-greater-than-left laterality effects were found for temporal lobe, superior temporal gyrus, amygdala, and hippocampal volumes. These results are consistent with previous preclinical and human studies that have indicated hormonal responsivity of these structures and extend quantitative morphologic findings from the adult literature. In addition to highlighting the need for large samples and sex-matched controls in pediatric neuroimaging studies, the information from this understudied age group may be of use in evaluating developmental hypotheses of neuropsychiatric disorders.

Adolescent↗

PubMed1996

A quantitative MRI study of the corpus callosum in children and adolescents.

Total midsagittal area and seven subdivisions of the corpus callosum were measured on magnetic resonance images of 114 healthy boys and girls, aged 4 to 18. Striking variability of size was noted for all measures. Total midsagittal corpus callosum area increased in a robust and linear fashion from ages 4 to 18 (slope = 13.1 mm2/year, P = 0.0001 and slope = 11.1 mm2/year, P = 0.0001 for females and males, respectively). Posterior and mid regions demonstrated greater age-related changes than anterior regions with the rostrum and genu (anterior regions) having reached adult sizes in the youngest of our subjects. There were no significant effects of sex for any measures. These findings support anatomical studies indicating ongoing myelination of higher association areas throughout adolescence, but raise intriguing questions about anterior-posterior gradients of interhemispheric myelination.

Adolescent↗

PubMed1996

Quantitative brain magnetic resonance imaging in attention-deficit hyperactivity disorder.

BACKGROUND: Anatomic magnetic resonance imaging (MRI) studies of attention-deficit hyperactivity disorder (ADHD) have been limited by small samples or measurement of single brain regions. Since the neuropsychological deficits in ADHD implicate a network linking basal ganglia and frontal regions, 12 subcortical and cortical regions and their symmetries were measured to determine if these structures best distinguished ADHD. METHODS: Anatomic brain MRIs for 57 boys with ADHD and 55 healthy matched controls, aged 5 to 18 years, were obtained using a 1.5-T scanner with contiguous 2-mm sections. Volumetric measures of the cerebrum, caudate nucleus, putamen, globus pallidus, amygdala, hippocampus, temporal lobe, cerebellum; a measure of prefrontal cortex; and related right-left asymmetries were examined along with midsagittal area measures of the cerebellum and corpus callosum. Interrater reliabilities were .82 or greater for all MRI measures. RESULTS: Subjects with ADHD had a 4.7% smaller total cerebral volume (P = .02). Analysis of covariance for total cerebral volume demonstrated a significant loss of normal right > left asymmetry in the caudate (P = .006), smaller right globus pallidus (P = .005), smaller right anterior frontal region (P = .02), smaller cerebellum (P = .05), and reversal of normal lateral ventricular asymmetry (P = .03) in the ADHD group. The normal age-related decrease in caudate volume was not seen, and increases in lateral ventricular volumes were significantly diminished in ADHD. CONCLUSION: This first comprehensive morphometric analysis is consistent with hypothesized dysfunction of right-sided prefrontal-striatal systems in ADHD.

Adolescent↗

PubMed1996

A technique for single-channel MR brain tissue segmentation: application to a pediatric sample.

A segmentation method is presented for gray matter, white matter, and cerebrospinal fluid (CSF) in thin-sliced single-channel brain magnetic resonance (MR) scans. The method is based on probabilistic modeling of intensity distributions and on a region growing technique. Interrater and intrarater reliabilities for the method were high, and comparison with phantom studies and hand-traced results from an experienced rater indicated good validity. The method was designed to account for spatially dependent image intensity inhomogeneities. Segmentation of MR brain scans of 105 (56 male and 49 female) healthy children and adolescents showed that although the total brain volume was stable over age 4-18, white matter increased and gray matter decreased significantly. There were no sex differences in total gray and white matter growth after correction for total brain volume. White matter volume increased the most in superior and posterior regions and laterality effects were seen in hemisphere tissue volumes. These findings are consistent with other reports, and further validate the segmentation technique.

Adolescent↗

PubMedDate not supplied

Quantitative magnetic resonance imaging of human brain development: ages 4-18.

Brain magnetic resonance images (MRI) of 104 healthy children and adolescents, age 4-18, showed significant effects of age and gender on brain morphometry. Males had larger cerebral (9%) and cerebellar (8%) volumes (P < 0.0001 and P = 0.008, respectively), which remained significant even after correction for height and weight. After adjusting for cerebral size, the putamen and globus pallidus remained larger in males, while relative caudate size was larger in females. Neither cerebral nor cerebellar volume changed significantly across this age range. Lateral ventricular volume increased significantly in males (trend for females), with males showing an increase in slope after age 11. In males only, caudate and putamen decrease with age (P = 0.007 and 0.05, respectively). The left lateral ventricles and putamen were significantly greater than the right (P = 0.01 and 0.001, respectively). In contrast, the cerebral hemispheres and caudate showed a highly consistent right-greater-than-left asymmetry (P < 0.0001 for both). All volumes demonstrated a high degree of variability. These findings highlight gender-specific maturational changes of the developing brain and the need for large gender-matched samples in pediatric neuropsychiatric studies.

Adolescent↗