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At least 631 records · Page 35Linked to original sources
PubMed2002

Sex differences in functional brain activation during a lexical visual field task.

Functional MRI was used to investigate sex differences in brain activation during a paradigm similar to a lexical-decision task. Six males and 6 females performed two runs of the lexical visual field task (i.e., deciding which visual field a word compared with a pseudoword was presented to). A sex difference was noted behaviorally: The reaction time data showed males had a marginal right visual field advantage and women a left visual field advantage. Imaging results showed that men had a strongly left-lateralized pattern of activation, e.g., inferior frontal and fusiform gyrus, while women showed a more symmetrical pattern in language related areas with greater right-frontal and right-middle-temporal activation. The data show evidence of task-specific sex differences in the cerebral organization of language processing.

Adult↗
PubMed1989

Surgical treatment of epilepsy: opportunities for research into basic mechanisms of human brain function.

Numerous technological developments in neurology have increased the ability to localize structural and functional abnormalities within the human brain. Such techniques have contributed to a renewed interest in resective surgical treatment for medically refractory partial seizures. Enhanced capacity to carry out detailed in vivo and in vitro measurements of neuronal activity in patients, during the course of presurgical evaluation and following surgical resection, now offers unprecedented opportunities for invasive research into normal and abnormal human cerebral function. Electrophysiological, microanatomical, biochemical and behavioral studies can be carried out without presenting undue risk or discomfort to the patient. Such research in a clinical setting presents difficulties in experimental design for the basic neuroscientist. Problems are reduced in clinical programs where diagnostic and surgical procedures are carried out in a standardized fashion according to specific protocols. The UCLA clinical protocol for anterior temporal lobectomy, based on presurgical evaluation with stereotactically implanted depth electrodes, is particularly amenable to the integration of basic research projects. This protocol and related ongoing research projects are described.

Brain Mapping↗
PubMed1990

Nutrition status and brain function in aging.

Biochemical indices of nutrition status assessed in 28 healthy persons aged greater than 60 y were related to cognitive performance and electroencephalographic (EEG) indices of neuropsychological function. Performance data were most frequently related to indices of nutrition status when tasks were demanding. Numerous correlations were also found between EEG indices and indices of thiamin, riboflavin, and iron nutriture. Certain observations, such as a decrement in alpha-wave activity in the EEG of subjects with low thiamin status, suggest that subtle neuropsychological impairment can occur in association with mild deficits in nutrition status. Other findings indicate that EEG frequency responses of older subjects with high iron status are similar to those of younger persons; however, these data are more difficult to interpret. The results suggest that further research on nutrition and neuropsychological function will lead to a better understanding of the role of nutrition in maintaining the functional integrity of the aging brain.

Aged↗
PubMedDate not supplied

Taste and smell phantoms revealed by brain functional MRI (fMRI).

PURPOSE: Our goal was to demonstrate the appearance of phantom tastes and smells (phantageusia and phantosmia, respectively) by use of functional MRI (fMRI) of the brain and to demonstrate the efficacy of drug treatment that inhibited both the subjective presence of these phantoms and the fMRI brain activation initiated by these phantoms. METHOD: Multislice FLASH MR or echo planar MR brain scans were obtained in two patients with phantageusia and phantosmia in response to memory of two tastants (salt and sweet); memory of two odors (banana and peppermint); actual smell of amyl acetate, menthone, and pyridine; and memory of phantom tastes and smells before and after treatment with thioridazine and haloperidol. Activation images were derived using correlation analysis, and ratios of brain area activated to total brain area were obtained. RESULTS: Prior to treatment, both patients experienced persistent birhinal and global oral obnoxious tastes and smells in the absence of any external stimulus. The fMRI response to memory of phantoms was activation in sensory-specific brain regions for taste and smell, respectively. fMRI activation was greater than for memory of any tastant or odorant or for actual smell of any odor. After treatment with thioridazine or haloperidol, which successfully inhibited each phantom in each patient, fMRI response to phantom memory was significantly inhibited and was significantly lower than for memory of any tastant or odorant or actual smell of any odorant. CONCLUSION: These results demonstrate that (a) phantom taste and smell can be revealed by fMRI brain activation, (b) brain activation in response to taste and smell phantoms is localized in sensory-specific brain regions for taste and smell, respectively, (c) brain activation in response to memory of each phantom initiated the greatest degree of activation we had previously measured, and (d) treatment with thioridazine or haloperidol inhibited both the presence of each phantom and its associated fMRI brain activation. This is the first study in which phantom tastes and smells have been demonstrated by an objective technique and treatment that inhibited the phantoms was characterized by objective inhibition of fMRI activation. These two patients represent a relatively common group that may be classified as having primary phantageusia and phantosmia distinct from those with phantoms or auras secondary to neurological, migrainous, psychiatric, or other causes.

Brain Mapping↗
PubMed2003

Manganese action in brain function.

Manganese, an essential trace metal, is supplied to the brain via both the blood-brain and the blood-cerebrospinal fluid barriers. There are some mechanisms in this process and transferrin may be involved in manganese transport into the brain. A large portion of manganese is bound to manganese metalloproteins, especially glutamine synthetase in astrocytes. A portion of manganese probably exists in the synaptic vesicles in glutamatergic neurons and the manganese is dynamically coupled to the electrophysiological activity of the neurons. Manganese released into the synaptic cleft may influence synaptic neurotransmission. Dietary manganese deficiency, which may enhance susceptibility to epileptic functions, appears to affect manganese homeostasis in the brain, probably followed by alteration of neural activity. On the other hand, manganese also acts as a toxicant to the brain because this metal has prooxidant activity. Abnormal concentrations of manganese in the brain, especially in the basal ganglia, are associated with neurological disorders similar to Parkinson's disease. Understanding the movement and action of manganese in synapses may be important to clarify the function and toxicity of manganese in the brain.

Animals↗
PubMed2025

Causal effect of three autoimmune diseases on brain functional networks and cerebrospinal fluid metabolites to underlie the pathogenesis of autoimmune psychosis: a two-sample mendelian randomization analysis.

BACKGROUND: Autoimmune diseases such as Systemic Lupus Erythematosus (SLE), Sj&#xf6;gren's Syndrome (SS), and Hashimoto's Thyroiditis (HT) frequently exhibit neuropsychiatric manifestations, including cognitive impairment, depression, anxiety, and so on, yet the exact pathogenesis underlying this association remain incompletely understood. Dysfunction of brain resting-state functional networks and cerebrospinal fluid (CSF) metabolite disturbances have been widely reported in psychiatric disorders. However, the application of resting-state functional magnetic resonance imaging (rsfMRI) and CSF metabolomics in the diagnosis and monitoring of autoimmune psychosis is still limited. METHODS: A two-sample Mendelian randomization (MR) analysis was performed to investigate the causal relationships between three autoimmune diseases (SLE, SS, and HT, n&#x2009;=&#x2009;14,267 to 402,090 individuals) and 191 rsfMRI phenotypes (n&#x2009;=&#x2009;47,276 individuals), as well as 338 CSF metabolites. The genome-wide association study (GWAS) of three autoimmune diseases was used as the exposure, whereas rsfMRI phenotypes and 338 CSF metabolites were treated as the outcome. Inverse variance weighted (IVW) with P value&#x2009;<&#x2009;0.05 was regarded as the primary approach for calculating causal estimates. Additionally, the false discovery rate (FDR)-adjusted P value (PFDR)&#x2009;<&#x2009;0.05 was utilized to account for multiple testing. MR Egger method, weighted median method, simple mode method and weighted mode method were used for sensitive analysis. RESULTS: Our analyses identified 5 causal relationships between SLE and the 191 rsfMRI phenotypes, 48 between SS and the 191 rsfMRI phenotypes, and 4 between HT and the 191 rsfMRI phenotypes. Additionally, we found 8 causal relationships between HT and CSF metabolites. Furthermore, all three diseases were significantly associated with the temporal lobe and triple networks (default mode network (DMN), salience network (SN), and central executive network (CEN)), which are the core brain regions and functional networks for cognition. Following FDR correction, 6 causal relationships between SS and the 191 rsfMRI phenotypes were further validated. CONCLUSIONS: Our study pinpoints important brain functional networks and CSF metabolites potentially implicated in the pathogenesis of psychiatric disorders associated with autoimmune diseases and highlights critical brain regions for the development of novel therapeutics.

Humans↗
PubMed2004

Static magnetic field influence on rat brain function detected by heart rate monitoring.

The aim of the present study was to identify the effects of a static magnetic field (SMF) on rat brain structures that control autonomic functions, specifically heart rate and heart rhythmicity. The experiments were carried out on 44 male Wistar rats under ketamine-xylazine anesthesia. SMF was induced using samarium-cobalt fused magnets (20 x 20 x 10 mm in size) placed bitemporally. Magnetic induction intensity was 100 mT on the surface of the head. Duration of magnetic field application was 15 min. An electrocardiogram was recorded from limb lead II, and both heart rate (average duration of cardiac cycles) and heart rhythmicity were analyzed before and after SMF application. SMF evoked changes in both heart rate and rhythm in 80% of the animals; the predominant effects were bradycardia and disappearance of respiratory sinus arrhythmia. However, the effectiveness of SMF in large measure depends on both functional peculiarities and functional activities of brain autonomic centers.

Animals↗
PubMed1984

A noninvasive approach to quantitative functional brain mapping with H2 (15)O and positron emission tomography.

Positron emission tomographic (PET) measurements of regional cerebral blood flow (rCBF) with intravenously administered 15O-labeled water and an adaptation of the Kety autoradiographic model are well suited to the study of functional-anatomical correlations within the human brain. This model requires arterial blood sampling to determine rCBF from the regional tissue radiotracer concentration (Cr) recorded by the tomograph. Based upon the well-defined, nearly linear relation between Cr and rCBF inherent in the model, we have developed a method for estimating changes in rCBF from changes in Cr without calculating true rCBF and thus without arterial sampling. This study demonstrates that quantitative functional brain mapping does not require the determination of rCBF from Cr when regional neuronal activation is expressed as the change in rCBF from an initial, resting-state measurement. Patterned-flash visual stimulation was used to produce a wide range of increases in rCBF within the striate cortex. Changes in occipital rCBF were found to be accurately estimated directly from Cr over a series of 56 measurements on eight subjects. This adaptation of the PET/autoradiographic method serves to simplify its application and to make it more acceptable to the subject.

Adult↗
PubMed2000

Structural and functional brain integrity of fetal alcohol syndrome in nonretarded cases.

PURPOSE: To determine the structural and functional integrity of the brain in a sample of nonretarded individuals diagnosed with fetal alcohol syndrome. SUBJECTS: The sample consisted of nineteen individuals who met the diagnostic criteria for fetal alcohol syndrome. METHODS: Intellectual function was assessed using the Wechsler Adult Intelligence Scale-Revised. Structural integrity of the brain was assessed using magnetic resonance imaging whereas functional integrity was assessed using positron emission tomography and (18)F-fluorodeoxyglucose. RESULTS: The mean Full Scale IQ was 80. 2 (range: 66-92). Only 1 magnetic resonance imaging was found to be abnormal. This abnormality was found for the subject with the lowest IQ. Decreases in relative regional cerebral metabolic rates were found in 5 brain regions comprising the thalamus and basal ganglia. CONCLUSION: These results when coupled with previous findings suggest a continuum of neuropathology in fetal alcohol syndrome. For cases with relatively mild intellectual deficits, the cause of the deficit is at a micro-level rather than a macro-level.

Adolescent↗
PubMedDate not supplied

[Endogenous neuropeptides and regulation of the brain functional plasticity].

This review analysed the data about the neuropeptides secreted from the different brain structures. Involvement of the endogenous neuropeptides in synaptic plasticity was tested at the model of long-term potentiation (LTP) as a form of learning and the memory formation. The most of these neuropeptides or their fragments involves in the induction and maintenance of the LTP and provides the transformation of short-term excitability of the neurones into the long-term one. They may be considered as nootropic compounds. It is proposed that the system of peptidergic regulation of neuronal plasticity functionates in the brain and there are a possibility to correct the activity of this system during the different pathology.

Animals↗
PubMed2003

Fast functional brain signal changes detected by diffusion weighted fMRI.

Functional magnetic resonance imaging (fMRI) has become the method of choice in the study of system neuroscience, as evidenced by an explosion of such literature in the past decade. Contrast mechanisms based on the blood oxygenation level, volume, and flow changes have been used to non-invasively detect brain activation secondary to the neuronal activity. However, because of the hemodynamic modulations inherent in these signals, their spatial and temporal characteristics are influenced by the complex geometry and varying delivery speed of the brain vasculature. Consequently, spatial dispersions and temporal delays are commonly seen in the brain activity using fMRI. It is thus of critical importance to investigate alternative contrast mechanisms that may offer shorter temporal delays and more direct spatial localization. In light of a recent phantom study which demonstrated the possibility to detect the destructive phase addition from the spatially incoherent, yet temporally synchronized, displacements caused by the Lorentz force experienced during electrical conduction within a strong magnetic field, we seek to apply similar imaging technique to investigate the functional signal changes that may provide alternative temporal and spatial characteristics. It is found that by using heavy diffusion weighting, which is one form of displacement encoding strategies, to remove the vascular signal and sensitize the minute and incoherent displacement, one can detect fast dynamic signal changes synchronized to the task. This finding may help take an initial step toward direct non-invasive MRI detection of the neuronal activity with improved temporal accuracy.

Adult↗
PubMed2002

Hyperbaric oxygenation affects rat brain function after carbon monoxide exposure.

The application of hyperbaric oxygenation (HBO2) has been recommended for correction of neurological injury in severely CO-poisoned patients. However, the mechanisms of HBO2 action on brain mitochondrial function under the circumstances is not yet understood completely. In the present study, the effect of HBO2 on the rat brain after CO exposure was evaluated by measuring the intramitochondrial NADH and its responses to anoxic test or repetitive induction spreading depression (SD) leading to brain activation. A unique monitoring system for bilateral monitoring of brain NADH redox state was used. Rats were exposed to 3000 ppm CO for 30 (group A) or 60 min (C). In groups B and D, after CO exposure, the rats were exposed to HBO2 (3 atm abs for 30 min). Following CO exposure in groups A and C, a definite decrease in the amplitude of the NADH response and significant increase in the number of waves of NADH was noted during induced cortical SD. Anoxic test in these two groups led to a significant decrease of maximum levels of NADH (reduction) at the end of observation. The amplitude, and the number of SD waves and magnitude of NADH deviation during anoxic test in group B after application of HBO2, was not significantly different from the values measured under the initial conditions. However, in group D, tendency of maintenance of the parameter's initial level was weaker or absent. The results obtained indicated that suppression of brain energy metabolism is a characteristic manifestation of CO poisoning in rats. Restoration of cerebral energy metabolism by adequate dosage of HBO2 may become an important factor for recovery of brain activities after CO poisoning.

Animals↗
PubMedDate not supplied

Estrogens and brain function.

Cognitive decline is well recognized during ageing but is often accelerated in women after menopause. Studies have shown that there are significant gender differences in brain ageing with significantly greater changes in brain structure, function and metabolism between females and males. Estrogens exert protective effects on neuronal cells in culture but the exact underlying mechanism for their neuroprotective effect in humans is not completely understood. Estrogens have been shown to affect the nervous system in many different ways: via binding to estrogen receptors (ERs) but also via multiple pathways. The results of small randomized trials and larger observational studies suggest a beneficial effect of estrogen therapy on cognitive function in symptomatic postmenopausal women. However, the results of the Women's Health Initiative Study (WHIMS) do not support this, at least not in women over the age of 65. Alzheimer's disease (AD) is two to three times more common in women than in men. Based on currently available data, routine therapeutic use of estrogens in women with AD is not justified but it may have a role in the prophylaxis of AD. The existing evidence supports the use of HRT only in women with menopausal symptoms for a few years following menopause.

Aged↗
PubMed1977

Evaluation of brain function in severe human head trauma with multimodality evoked potentials. Part 1: Evoked brain-injury potentials, methods, and analysis.

Methods for obtaining multimodality evoked potentials, somatosensory, visual, auditory, and auditory brain-stem potentials in patients with severe head trauma are described. A method of analyzing abnormal multimodality evoked potentials (graded evoked brain-injury potentials) is proposed that defines the degree of abnormality of the electrophysiological data and expresses it simply in four grades per modality. Data from 20 normal subjects are given for comparison with the abnormal data obtained from 51 patients with head trauma.

Acoustic Stimulation↗