The results of preliminary analysis at the first stage of the study have demonstrated significant relationships between electrophysiological
parameters and the levels of a number of metabolites (measured by proton magnetic resonance spectroscopy) in the dorsolateral
prefrontal cortex of the left cerebral hemisphere. The observed relationships are assumed to be mediated by individual-specific
characteristics of activation of this cerebral region and its contribution to information processing. The neurophysiological
markers of the weakened functional state of the brain are associated with decreased levels of N-acetyl aspartate and choline-containing
compounds and an increased level of creatin/phosphocreatin in the tested area of the left prefrontal cortex.
[Show abstract][Hide abstract] ABSTRACT: Elevated brain Cho has been shown within the basal ganglia and frontal (i.e., orbitofrontal and cingulate) cortices in patients with mood disorders utilizing Proton Magnetic Resonance Spectroscopy (1H-MRS). We sought to determine the relationship between Cho and mood in a cohort of healthy young subjects.
Twenty-seven subjects without neurologic or psychiatric disorders were evaluated with the Positive and Negative Affect Scale and underwent 1H-MRS of bilateral frontal and occipito-parietal white matter.
We found that Cho in the left frontal lobe was inversely correlated with Positive Affect [F(1,24) = 19.2, p <.001, r(2) =.45].
Our results highlight the important involvement of Cho underlying the integration of affective processing within prefrontal circuitry, and may indicate increased myelin turnover in subjects with lower Positive Affect. Further efforts will be necessary to determine if high Cho is associated with increased incidence of mood disorders throughout life.
[Show abstract][Hide abstract] ABSTRACT: Reduced brain N-acetyl-aspartate (NAA) has been repeatedly found in chronic schizophrenia and suggests neuronal loss or dysfunction. However, the potential confounding effect of antipsychotic drugs on NAA has not been resolved. We studied 32 minimally treated schizophrenia patients and 21 healthy subjects with single-voxel proton magnetic resonance spectroscopy ((1)H-MRS) of the frontal and occipital lobes, caudate nucleus, and cerebellum. Concentrations of NAA, Choline, and Cre were determined and corrected for the proportion of cerebrospinal fluid (CSF) in the voxel. Patients were treated in a randomized-controlled double-blind manner with either haloperidol or quetiapine. (1)H-MRS was repeated every 6 months for up to 2 years. There was a group main effect for baseline NAA with lower global NAA in schizophrenia subjects before treatment compared to healthy controls. Global NAA was directly related to measures of global cognitive performance in the whole subject sample. Following treatment with haloperidol or quetiapine, there were no changes in NAA in any of the regions studied. Early in the illness, schizophrenia patients already demonstrate subtle reductions in NAA. Treatment with typical or atypical antipsychotic medications for several months does not result in NAA changes.
Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 09/2008; 33(10):2456-66. DOI:10.1038/sj.npp.1301631 · 7.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Previous research has found that properties of automatic processing do not always co-occur, suggesting that the acquisition rates may differ. The present study investigated the acquisition rate of several of these properties by employing additive factors logic, dual task methodology, and event-related brain potentials. Seven subjects participated in a ten session experiment in which they performed two tasks, a visual/memory search task and a pursuit step tracking task, both together and separately. RT and P300 latency measures indicated that parallel processing of the display was achieved early in training in the consistent mapping condition. This processing was unaffected by dual task demands. An analysis of RT/P300 ratios suggests that another form of perceptual efficiency was achieved later in practice in both the varied and consistently mapped search tasks. This effect was larger in the consistent mapping condition. Reductions in the slope of the memory set function occurred significantly earlier for P300 latency than for RT, suggesting that the stimulus evaluation processes became automated more rapidly than the response selection components of memory search. Consistent with an analysis of the processing demands of the two tasks, the introduction of the tracking task and an increase in tracking difficulty produced equivalent interference during consistent and varied mapping conditions. Results are discussed in terms of models of skill, skill acquisition and component task automaticity.
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