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At least 1,261 records · Page 70Linked to original sources
PubMed2001

Action sites of adrenomedullin in the rat brain: functional mapping by Fos expression.

The effects of intracerebroventricular (icv) administration of adrenomedullin (AM) and proadrenomedullin NH2-terminal 20 peptide (PAMP) on the expression of Fos in the central nervous system (CNS) were examined in conscious rats, using immunohistochemistry. Fos-like immunoreactivity (LI) was detected in various brain areas of the rats, including the supraoptic nucleus, the paraventricular nucleus, the locus coeruleus, the area postrema and the nucleus of the tractus solitarius 90 min after icv administration of AM. Few cells with Fos-LI were found in the CNS 90 min after icv administration of saline. Fos-LI was also detected in the various hypothalamic areas after icv administration of PAMP. These results suggest that centrally administered AM and PAMP may cause physiological responses through the activation of a neural network in the hypothalamus and the brainstem.

Adrenomedullin↗
PubMed2002

[Calcium signaling and brain functions].

Calcium signaling plays a critical role in various cell types by activation of receptors and Ca2+ channels in response to neurotransmitters, hormones, growth, factors etc. Although a variety of functions of intracellular Ca2+ are reported, Ca2+/calmodulin-dependent protein kinases (CaMK) are involved in their mediation. We have been studying on CaMK I, II, III, IV and K in the dynamic regulation in the cells in relation to functions. In this study, we elucidated the structures of the isoforms of CaMKII subunits with nuclear translocation signal (NTS). NTS is included in the variable domain following the regulatory domain with a sequence of KKRK. The isoforms of CaMK subunits such as alpha B, gamma A, gamma A.B, delta 3 and delta 7 contain NTS in the sequences of the structures. Transfection of the isoforms with NTS into NG108-15 cells stimulated the expression of brain-derived neurotrophic factor in the cytoplasm. Activation of CaMKII and IV and mitogen-activated protein kinase (MAPK) was observed during long-term potentiation (LTP) induction in the CA1 area of hippocampus. The activation of CaMKII was sustained for a long period, whereas that of CaMKIV and MAPK was transient. The results suggest that CaMKII is involved in LTP induction, while CaMKIV and MAPK are rather involved in LTP maintenance. We present and discuss our recent studies on regulation of CaMKs in neuronal functions.

Brain↗
PubMed1991

[The effect of sermion on brain function in diabetics].

The vasoactive drug sermion was used for the treatment of patients suffering of diabetes mellitus with clinical manifestations of central neuropathy. A course of sermion treatment effected positively the clinical course of neuropathy also confirmed electroencephalographically and by the parameters of visual and somatosensory evoked potentials of the brain. Results indicate the possibility of using sermion in the treatment of brain affections in patients with diabetes mellitus.

Adult↗
PubMed1992

Electrical impedance tomography (EIT) of brain function.

Electrical impedance tomography (EIT) is a recently developed technique which enables the internal impedance of an object to be imaged non-invasively. Images are at present reconstructed from measurements made at 51 kHz with a ring of sixteen electrodes placed around the subject. A minimum data set is acquired in 40 msec, and an image can be reconstructed in about 5 sec. The technique is rapid, safe, portable and inexpensive, and so is ideal for non-invasive continuous imaging at the bedside. It cannot be used at present to image changes in the brain with scalp electrodes, as the relative resistance of the skull is too great. It should be possible to use it in the near future with a ring of subdural electrodes to produce images of brain regions undergoing anoxic depolarization in conditions such as epilepsy or stroke. It may be possible to use it in the future to image impedance changes related either to blood flow or depolarization during functional activity. Images of depolarization could be produced with a temporal resolution of milliseconds and would form a substantial advance in neuroscience methodology.

Action Potentials↗
PubMed2003

PET imaging of brain function while puncturing the acupoint ST36.

OBJECTIVE: To explore the experimental method of obtaining position emission tonogiaphy (PET) imaging evidence of changes in cerebral function by puncturing the Stomach 36 (ST36, Zusanli) acupoint. METHODS: Data on changes of cerebral glycometabolism were obtained from six healthy male volunteers with positron emission tomography. Visual experimental evidence, as well as statistical parametric mapping (SPM), was gathered while puncturing the ST36 (Zusanli, right leg) acupoint. RESULTS: There was increased glycometabolism in the hypothalamus, head of the caudate nucleus, temporal lobe, the sinistral cerebellum, postcentral gyrus, and brain stem while the acupoint ST36 was being punctured. CONCLUSIONS: Acupuncture on ST36 can lead to increase in glycometabolism in the vegetative nerve centers, which is correlated with gastric function. Visual experimental evidence of ST36 acupuncturing on functional gastrointestinal disorder was obtained in our study.

Acupuncture↗
PubMed2001

Shedding light on brain function: the event-related optical signal.

One of the basic goals of cognitive psychology is the analysis of the covert processes that occur between stimulus and response. In the past 20-30 years, the tools available to cognitive psychologists have been augmented by a number of imaging techniques for studying the 'brain in action' in a non-invasive manner. These techniques have their strength in either temporal or spatial information, but not both. We review here recent advances of a new approach, the event-related optical signal (EROS). This method allows measurements of the time course of neural activity in specific cortical structures, thus combining good spatial and temporal specificity. As an example, we show how EROS can be used to distinguish between serial and parallel models of information processing.

Journal Article↗
PubMed2001

[Depression, stress and brain function].

Many patients with major depression have elevated serum cortisol, which cannot be suppressed with dexamethasone. This points to a disturbance in the hypothalamus-pituitary-adrenal (HPA) axis, which might have pathogenetic importance. Recent investigations with MRI have shown an increased frequency of generalised, as well as localised atrophy in the brains of depressed patients. The reduced volume of the hippocampus is particularly interesting, because of the participation of this structure in the regulation of the individual's stress response. Furthermore, the hippocampus is of major importance for cognitive processes. There is evidence that the increased cortisol concentration is neurotoxic and may cause atrophy, as is known from Cushing's disease. This is supported by studies of the accumulated duration of depressive episodes, and also by the fact that drugs that dampen the HPA axis have proved to have antidepressant properties in clinical controlled, double-blind studies. This points to new principles in the treatment of major depression and underlines the importance of early intervention in order to prevent cerebral atrophy, which is probably reversible at the beginning of the disease process.

Antidepressive Agents↗
PubMed1999

Functional brain imaging in the resting state and during activation in Alzheimer's disease. Implications for disease mechanisms involving oxidative phosphorylation.

In vivo brain imaging of patients with Alzheimer's disease (AD) using positron emission tomography (PET) demonstrates progressive reductions in resting-state brain glucose metabolism and blood flow in relation to dementia severity, more so in association than primary cortical regions. During cognitive or psychophysical stimulation, blood flow and metabolism in the affected regions can increase to the same extent in mildly demented AD patients as in age-matched controls, suggesting that energy delivery is not rate limiting. Activation declines with dementia severity, and is markedly reduced in severely demented patients. These results suggest that there is an initial "normal" functionally-responsive stage in AD, followed by a late less responsive stage. Studies of biopsied and postmortem brain indicate that the initial stage is accompanied by selective and potentially reversible down-regulation of the brain enzymes, including cytochrome oxidase, which mediate mitochondrial oxidative-phosphorylation.

Alzheimer Disease↗
PubMed2003

Functional brain imaging in irritable bowel syndrome with rectal balloon-distention by using fMRI.

AIM: Irritable bowel syndrome (IBS) is characterized by abdominal pain and changes in stool habits. Visceral hypersensitivity is a key factor in the pathophysiology of IBS. The aim of this study was to examine the effect of rectal balloon-distention stimulus by blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) in visceral pain center and to compare the distribution, extent, and intensity of activated areas between IBS patients and normal controls. METHODS: Twenty-six patients with IBS and eleven normal controls were tested for rectal sensation, and the subjective pain intensity at 90 ml and 120 ml rectal balloon-distention was reported by using Visual Analogue Scale. Then, BOLD-fMRI was performed at 30 ml, 60 ml, 90 ml, and 120 ml rectal balloon-distention in all subjects. RESULTS: Rectal distention stimulation increased the activity of anterior cingulate cortex (35/37), insular cortex (37/37), prefrontal cortex (37/37), and thalamus (35/37) in most cases. At 120 ml of rectal balloon-distention, the activation area and percentage change in MR signal intensity of the regions of interest (ROI) at IC, PFC, and THAL were significantly greater in patients with IBS than that in controls. Score of pain sensation at 90 ml and 120 ml rectal balloon-distention was significantly higher in patients with IBS than that in controls. CONCLUSION: Using fMRI, some patients with IBS can be detected having visceral hypersensitivity in response to painful rectal balloon-distention. fMRI is an objective brain imaging technique to measure the change in regional cerebral activation more precisely. In this study, IC and PFC of the IBS patients were the major loci of the CNS processing of visceral perception.

Adult↗
PubMed2000

Cytoprotection does not preserve brain functionality in rats during the acute post-stroke phase despite evidence of non-infarction provided by MRI.

In animal models of stroke the promise of a therapy is commonly judged from infarct size measurements, assuming that a reduction in infarct size results in reduction of the functional deficits. We have evaluated the validity of the concept that structural integrity translates into functional integrity during the acute post-stroke period (24 h). Unilateral permanent middle cerebral artery occlusion (pMCAO) in Fischer F344 rats leads to infarcts comprising the ipsilateral striatum and cortical structures, including the somatosensory cortex. Infarct volumes were assessed using magnetic resonance imaging (MRI) methods (T(2), diffusion, perfusion MRI). The functional integrity of the somatosensory cortex was assessed by functional MRI (fMRI) measuring changes in local cerebral blood volume, and by assessing the forelimb grip strength and the beam-walking performance of the animals. Treatment with the calcium antagonist isradipine (2.5 mg/kg injected s.c. immediately after pMCAO) reduced the total infarct size by more than 40% compared to vehicle-injected controls. In particular, the ipsilateral somatosensory cortex appeared normal in diffusion- and T(2)-weighted MRI images. In sham-operated rats simultaneous electrical stimulation of both forepaws led to similar activation of both somatosensory cortices, while in pMCAO animals given vehicle only the contralateral cortex showed an fMRI response. Similarly, in pMCAO rats treated with isradipine, functional activation following bilateral electrical stimulation was only detected in the contralateral somatosensory cortex despite the normal appearance of the ipsilateral cortex in MRI images. Furthermore, fMRI responses to pharmacological stimulation with bicuculline were virtually absent in the ipsilateral somatosensory cortices both in vehicle- and isradipine-treated rats. Finally there was no significant difference between vehicle- and isradipine-treated animals upon the performance of beam-walking test or in forelimb grip strength. It is concluded that during the acute (24 h) post-occlusion period, structural integrity in the somatosensory cortex revealed by MRI does not translate into preservation of function.

Adenosine Triphosphate↗
PubMed1987

[How to evaluate recirculation effect on brain function after global ischemia--broad spectral EEG analysis by Fourier method].

EEG alterations after 5 or 10 minutes of global ischemia were investigated for 6 hours of postischemic period in 18 adult cats, together with biophysiological parameters such as cerebral blood flow, intracranial pressure, systemic blood pressure, heart rate, and blood gases. Our EEG analytical system is composed of high fidelity pre-amplifier, AA 6 MK II (Medelec Limited, England) and signal processor 7T 08 (NEC-SanEi, Japan). It is qualified to analyze frequencies up to 20 kHz within 3 dB cut-off. Particular features of our EEG analytical method are focused on Fourier analysis about broad frequency bands, frequency and amplitude spectra to be expressed on bi-logarithmic graph and direct EEG recordings from various structures of the brain. On the basis of fluctuation theory following 3 types were divided; Type f which corresponds to 1/f fluctuation, Type L which corresponds to Lorentzian fluctuation, Type f+L which is the sum of Type f and L. The distribution of these types in the central nervous system corresponds with cortical structures, spinal cord and brain stem respectively. In conclusion, there was a good correlation between EEG and blood flow in the motor cortex. The functional reversibility after ischemia was different according to the types. Type f structures, namely the motor cortex, hippocampus and amygdala were vulnerable and Type f+L structures namely ventrolateral nucleus of the thalamus and midbrain reticular formation tended to recover or stay in preservation.

Animals↗
PubMed2006

Functional brain asymmetry, attentional modulation, and interhemispheric transfer in boys with Tourette syndrome.

We tested the hypothesis that children with Tourette syndrome (TS) would exhibit aberrant brain lateralization compared to a healthy control (HC) group in an attention-modulation version of a verbal dichotic listening task using consonant-vowel syllables. The modulation of attention to focus on the right ear stimulus in the dichotic listening situation is thought to involve the same prefrontal attentional and executive functions that are involved in the suppression of tics, whereas, performance when focusing attention on the left ear stimulus additionally involves a callosal transfer of information. In light of presumed disturbances in transfer of information across the corpus callosum, we hypothesized that children with TS would, however, have difficulty modulating the functional lateralization that ensues through a shift of attention to the left side. This hypothesis was tested by exploring the correlations between CC size and left ear score in the forced-left condition. Twenty boys with TS were compared with 20 age- and handedness-matched healthy boys. Results indicated similar performance in the TS and HC groups for lateralization of hemispheric function. TS subjects were also able to shift attention normally when instructed to focus on the right ear stimulus. When instructed to focus attention on the left ear stimulus, however, performance deteriorated in the TS group. Correlations with CC area further supported the hypothesized presence of deviant callosal functioning in the TS group.

Adolescent↗
PubMed2006

Changes in brain function (quantitative EEG cordance) during placebo lead-in and treatment outcomes in clinical trials for major depression.

OBJECTIVE: Decreases in prefrontal electroencephalogram (EEG) cordance that are detectable as early as 48 hours after the start of medication have been related to clinical outcome in treatment trials for major depressive disorder. The relationship between brain changes during the placebo lead-in phase and medication treatment outcome is unknown. The authors hypothesized that decreases in prefrontal cordance during the placebo lead-in phase would be associated with better clinical outcome in subjects treated with antidepressants. METHOD: Data were pooled examining 51 adults with major depressive disorder from two independent double-blind placebo-controlled trials. A 1-week single-blind placebo lead-in phase preceded 8 weeks of randomized treatment with medication (fluoxetine 20 mg or venlafaxine 150 mg) or placebo. The authors obtained quantitative EEG cordance measures at baseline and at the end of the placebo lead-in period. Relationships between regional cordance changes at the end of the placebo lead-in period and clinical outcome (the final 17-item Hamilton Rating Scale for Depression scores) were examined using multiple linear regression analysis. RESULTS: As hypothesized, decreases in prefrontal cordance during the placebo lead-in period were associated with lower final Hamilton depression scale scores in subjects randomly assigned to medication. Prefrontal changes explained 19% of the variance in final Hamilton depression scale scores. CONCLUSIONS: Neurophysiological changes during a placebo lead-in period may serve as nonpharmacodynamic biomarkers of eventual treatment outcomes in clinical trials for major depressive disorder.

Adult↗
PubMed1994

Nuclear magnetic resonance spectroscopy: biochemical evaluation of brain function in vivo and in vitro.

Nuclear magnetic resonance spectroscopy (MRS) offers a unique opportunity to monitor mmolar concentrations of high energy phosphates, glucose, lactate and amino acids. The possibility of obtaining information about chemical constituents noninvasively is of great importance. MRS and chemical shift imaging (CSI) are emerging as tools for tumor grading, monitoring of treatment, ischemia research, in pediatric research for follow-up of children with borderline mental retardation, for defining brain death and to define epileptic foci. It is important to know which cell type (neuronal or glial) shows changes as a result of external manipulations (e.g. excitotoxins) or internal changes (brain pathology). Metabolic studies have been carried out on brain cell cultures. By using 13C labeled glucose and acetate in combination with 13C MRS it was shown that astrocytes release lactate, glutamine, citrate and alanine and that cerebral cortical neurons use glutamine released from astrocytes as a precursor for GABA synthesis. An important feature in MRS is the localization of N-acetyl aspartate in neurons, since this enables monitoring of neuronal reactions, such as survival after neurotoxic insults. Recent advances have yielded high speed functional echo planar imaging (EPI) techniques that are sensitive to changes in cerebral blood volume, blood flow and blood oxygenation (Functional MRI). During cognitive task performance, local alterations in neuronal activity induce local changes in cerebral metabolism and cerebral perfusion, which can now be detected with MRI.

Animals↗
PubMed2001

Effect of irradiation at the early foetal stage on adult brain function of mouse: learning and memory.

PURPOSE: To study the long-term effect of early foetal irradiation on the learning and memory in the adult mouse. MATERIALS AND METHODS: The abdominal area of pregnant Swiss albino mice was exposed to a single dose of 0.25-1.5Gy gamma-radiation on the 14th day of gestation and the mice were left to deliver their offspring. At 6 months of age, the learning and memory functions of the F(1) mice were tested by hole-board activity, conditioned avoidance response and radial arm maze performance. The animals were again subjected to the radial arm maze test at 12 and 18 months of age. RESULTS: There was a significant dose-dependent decrease in the learning ability and memory retention of 6-month-old mice at doses > 0.25Gy. The significant changes persisted to 18 months of age in mice exposed to >or= 0.5Gy. All changes showed a linear dose-response at doses < 1Gy. CONCLUSIONS: The gestational day 14 of Swiss albino mice is a sensitive stage in brain development to gamma-ray-induced impairment of learning and memory during the adult life. Permanent deficits in these functions can be induced by a dose of approximately 0.5Gy at this stage, when the developmental activity of the cerebral cortex is at its peak.

Age Factors↗