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Biomedical subjects

Arthur Toga

Publications and source records attributed to Arthur Toga.

6 recordsLinked to original sources
PubMed2006

Hippocampal volume in childhood complex partial seizures.

PURPOSE: This study compared hippocampal volume in children with cryptogenic epilepsy, all of whom had complex partial seizures (CPS), and age and gender matched normal children controlling for between group differences in IQ and demographic variables (e.g., age, gender, ethnicity, socioeconomic status). It also examined the relationship between hippocampal volumes and seizure variables in the patients. METHODS: Using quantitative magnetic resonance imaging (MRI), we compared the hippocampal volumes of 19 medically treated children with CPS, aged 6-14 years, to 21 age and gender matched normal children. RESULTS: The children with CPS had significantly smaller total hippocampal volumes than the normal children. This finding was accounted for primarily by significantly smaller anterior hippocampal volumes. Within the CPS group, smaller total and posterior hippocampus volumes were significantly associated with longer duration of illness. Anterior hippocampal volumes, however, were unrelated to seizure variables. CONCLUSIONS: These findings imply impaired development of the hippocampus, particularly the anterior hippocampus, and a differential effect of the underlying illness and on-going seizures on hippocampal development in medically controlled pediatric CPS.

Adolescent↗
PubMed2005

Near-infrared spectroscopy (NIRS) in cognitive neuroscience of the primate brain.

We describe the use of near-infrared spectroscopy (NIRS) as a suitable means of assessing hemodynamic changes in the cerebral cortex of awake and behaving monkeys. NIRS can be applied to animals performing cognitive tasks in conjunction with electrophysiological methods, thus offering the possibility of investigating cortical neurovascular coupling in cognition. Because it imposes fewer constraints on behavior than fMRI, NIRS appears more practical than fMRI for certain studies of cognitive neuroscience on the primate cortex. In the present study, NIRS and field potential signals were simultaneously recorded from the association cortex (posterior parietal and prefrontal) of monkeys performing two delay tasks, one spatial and the other non-spatial. Working memory was accompanied by an increase in oxygenated hemoglobin mirrored by a decrease in deoxygenated hemoglobin. Both the trends and the amplitudes of these changes differed by task and by area. Field potential records revealed slow negative potentials that preceded the task trials and persisted during their memory period. The negativity during that period was greater in prefrontal than in parietal cortex. Between tasks, the potential differences were less pronounced than the hemodynamic differences. The present feasibility study lays the groundwork for future correlative studies of cognitive function and neurovascular coupling in the primate.

Algorithms↗
PubMed2005

Age-related morphology trends of cortical sulci.

The age-related trends of the width and the depth of major cortical sulci were studied in normal adults. Ninety healthy subjects (47 males, 43 females) age 20-82 years were evaluated. Measurements of average sulcal width and depth in 14 prominent sulcal structures per hemisphere were performed with high-resolution anatomical MRI. The average sulcal width increased at a rate of about 0.7 mm/decade, while the average sulcal depth decreased at a rate of about 0.4 mm/decade. Sulcal age-related trends were found to be highly influenced by gender in the superior temporal, collateral, and cingulate sulci (P < 0.05), with males showing more pronounced age-related change in sulcal width than females. Sulcal structures located in multimodal cortical areas showed more profound age-related changes than sulcal structures in unimodal cortical areas (P < 0.05).

Adult↗
PubMed2002

Frontal white matter biochemical abnormalities in late-life major depression detected with proton magnetic resonance spectroscopy.

OBJECTIVE: Neuroanatomical abnormalities have been identified in patients with late-life mood disorders by using magnetic resonance imaging. This study examined the biochemical correlates of late-life major depression in the frontal gray and white matter by using single-voxel proton spectroscopy. METHOD: Twenty elderly patients with major depression and 18 comparison subjects similar in age and gender to the patients were scanned on a 1.5-T magnetic resonance scanner with head coil. Voxels were placed in the left dorsolateral white matter and bilaterally in the anterior cingulate gray matter. Absolute levels of N-acetylaspartate, choline, myo-inositol, and creatine were estimated with the LC-Model algorithm. Ratios of metabolite to creatine levels were computed from the absolute values. RESULTS: myo-Inositol/creatine and choline/creatine ratios were significantly higher in the frontal white matter in the major depression group than in the comparison group. The groups had no significant differences in the metabolite ratios in the gray matter. CONCLUSIONS: Biochemical changes in the white matter may provide some of the neurobiological substrates to late-life major depression.

Aged↗
PubMedDate not supplied

Sex differences in brain structure in geriatric depression.

OBJECTIVE: In an exploratory study, authors compared patients with late-life major depression (MDD) and age-matched control subjects to examine sex differences in frontal and orbito-frontal (OFC) regional brain volumes. METHODS: The study sample comprised 41 patients with MDD and 41 controls. Subjects underwent comprehensive neuropsychiatric examinations and magnetic resonance imaging (MRI) scans. Corrected frontal and OFC gray-matter volumes were compared among men and women in both groups. RESULTS: The depression group had lower MMSE scores, greater severity of medical burden, apathy, psychomotor retardation, and poor health-related quality of life than the controls. Men in both groups had a greater severity of medical burden, apathy, and psychomotor retardation than women. The depression group had smaller OFC total and gray-matter volumes than the controls after matching for age. Men had smaller frontal-matter volumes than women in both groups. The diagnosis x sex interaction in brain regional volumes was observed only after controlling for medical burden. CONCLUSIONS: Sex differences in brain neuroanatomy may be important in the pathophysiology of geriatric depression. Men may be susceptible to atrophy in frontal subregions. Medical burden may contribute to the diagnosis x sex interaction in brain regional volumes.

Aged↗