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PubMed2004

Structural and functional brain changes in posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is a highly disabling condition that is associated with intrusive recollections of a traumatic event, hyperarousal, avoidance of clues associated with the trauma, and psychological numbing. The field of neuroimaging has made tremendous advances in the past decade and has contributed greatly to our understanding of the physiology of fear and the pathophysiology of PTSD. Neuroimaging studies have demonstrated significant neurobiologic changes in PTSD. There appear to be 3 areas of the brain that are different in patients with PTSD compared with those in control subjects: the hippocampus, the amygdala, and the medial frontal cortex. The amygdala appears to be hyperreactive to trauma-related stimuli. The hallmark symptoms of PTSD, including exaggerated startle response and flashbacks, may be related to a failure of higher brain regions (i.e., the hippocampus and the medial frontal cortex) to dampen the exaggerated symptoms of arousal and distress that are mediated through the amygdala in response to reminders of the traumatic event. The findings of structural and functional neuroimaging studies of PTSD are reviewed as they relate to our current understanding of the pathophysiology of this disorder.

Amygdala↗
PubMed1996

[The electrophysiological characteristics of brain function in mental disorders in participants in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station].

150 liquidators who had worked in the Chernobyl accident area were examined. All of them had mental diseases. Both alpha-rhythms disorganisation and increase of beta-1 activity were usually observed in brain cortex sensomotor areas of 43 patients as compared with 17 healthy individuals. Meanwhile alpha-activity was significantly decreased especially in the left hemispheres of patients with psycho-organic syndrome. The majority of patients were characterized by both enhanced reaction to light flashes rhythm assimilation and the decrease of nonspecific and skin-galvanic reactions to the light stimulus. The conclusion is made about the systemic CNS damage in such patients that was more pronounced in psycho-organic syndrome.

Adult↗
PubMed1996

Ultrafast perfusion-weighted MRI of functional brain activation in rats during forepaw stimulation: comparison with T2 -weighted MRI.

A fast version of the arterial spin tagging technique for the detection of cerebral perfusion is presented. Based on adiabatic spin inversion in combination with snapshot FLASH imaging, our technique allows the recording of perfusion changes with a temporal resolution of about 3 s. Differences of cerebral perfusion dependent on the choice of anesthesia were observed in rat brain. Furthermore, with this arterial spin tagging method we demonstrated perfusion increases in the somatosensory cortex of anaesthetized rats during forepaw stimulation. Comparison of the activated areas in the T2 -weighted BOLD images and the perfusion-weighted images showed good spatial correspondence, but the sensitivity to the functional activation was more than ten times higher in the perfusion technique.

Anesthesia↗
PubMed1988

[Hypothalamic pituitary function in brain death patients--from blood pituitary hormones and hypothalamic hormones].

According to the report of the Health and Welfare Ministry's research committee on brain death (1985), "brain death is defined as an irreversible cessation of the total brain function including brain stem." However, in brain death patients, whether the hypothalamic function which belongs to the brain stem function has completely ceased or not is unknown. In order to evaluate the hypothalamic function in brain death patients, the blood levels of the pituitary hormones and hypothalamic hormones were measured, and anterior pituitary stimulation test with triple bolus injection (TRH 500 micrograms, LH-RH 100 micrograms, regular insulin 0.3-0.7 unit/kg) was performed. The subjects were 13 brain death patients whose clinical states fully satisfied the criteria proposed by the committee. 1) The average blood levels of anterior pituitary hormones in these brain death patients were within normal range, and that of growth hormone was more than the twice of the normal level. 2) The blood anterior pituitary hormones were detectable in almost all cases even several days after the diagnosis of the brain death. 3) LH reserve was maintained in three cases. FSH reserve was maintained in three cases. Prolactin reserve was maintained in two cases. TSH reserve was maintained in one case. 4) Blood ADH (antidiuretic hormones) were detectable in 7 cases out of 9 cases. The blood ADH level of one case, in particular, was rather high (above 10 pg/ml). 5) Histopathologically anterior pituitaries were examined in three autopsy cases. The central necrotic areas were observed in all cases, but normal pituitary tissues existed peripherally. And all anterior pituitary hormones could be recognized immunohistochemically. 6) The blood levels of the hypothalamic hormones (GRF, CRF, LH-RH) were measured in four cases. The hypothalamic hormones were detectable in all cases. In one case, the levels of GRF were within normal range even 9 or 15 days after the diagnosis of brain death.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

[Cognitive brain function disorders in patients with leukoaraiosis confirmed by computed tomography].

118 patients with leukoaraiosis confirmed by CT were neuropsychologically examined. 68 persons were excluded because of occurrence of other changes in CT scans. The study concerns the group of 29 women (58%) and 21 men (42%) in age 44-89 (middle 72 +/- 9.9). The most frequent were fronto-subcortical and frontal syndromes (25 cases). Predominance of parieto-occipital syndrome was confirmed in 2 cases; 9 patients presented both frontal and parieto-occipital syndromes. In 11 cases only single dysfunction were founded, and 3 persons presented normal state of cognitive functions. There was no distinct correlation between degree of leukoaraiosis and character of neuropsychological disturbances.

Aged↗
PubMed1988

Anoxic brain function: molecular mechanisms of metabolic depression.

An examination of the kinetic parameters of phosphofructokinase, pyruvate kinase and glycogen phosphorylase, and the cellular concentration of fructose 2,6-bisphosphate during anoxia in the turtle Pseudemys scripta showed that the total activity of glycogen phosphorylase, and the phosphofructokinase inhibition constants for citrate and ATP were decreased in anoxic turtle brain. These results suggest that the ability of turtle brain to survive extended periods of anoxia is the result of metabolic rate depression regulated, at the molecular level, by enzyme inactivation through anoxia-induced covalent modification.

Adenosine Triphosphate↗
PubMed2004

Columnar specificity of microvascular oxygenation and volume responses: implications for functional brain mapping.

Cortical neurons with similar properties are grouped in columnar structures and supplied by matching vascular networks. The hemodynamic response to neuronal activation, however, is not well described on a fine spatial scale. We investigated the spatiotemporal characteristics of microvascular responses to neuronal activation in rat barrel cortex using optical intrinsic signal imaging and spectroscopy. Imaging was performed at 570 nm to provide functional maps of cerebral blood volume (CBV) changes and at 610 nm to estimate oxygenation changes. To emphasize parenchymal rather than large vessel contributions to the functional hemodynamic responses, we developed an ANOVA-based statistical analysis technique. Perfusion-based maps were compared with underlying neuroanatomy with cytochrome oxidase staining. Statistically determined CBV responses localized accurately to individually stimulated barrel columns and could resolve neighboring columns with a resolution better than 400 microm. Both CBV and early oxygenation responses extended beyond anatomical boundaries of single columns, but this vascular point spread did not preclude spatial specificity. These results indicate that microvascular flow control structures providing targeted flow increases to metabolically active neuronal columns also produce finely localized changes in CBV. This spatial specificity, along with the high contrast/noise ratio, makes the CBV response an attractive mapping signal. We also found that functional oxygenation changes can achieve submillimeter specificity not only during the transient deoxygenation ("initial dip") but also during the early part of the hyperoxygenation. We, therefore, suggest that to optimize hemodynamic spatial specificity, appropriate response timing (using < or =2-3 sec changes) is more important than etiology (oxygenation or volume).

Animals↗
PubMedDate not supplied

[Functional brain asymmetry and alpha rhythm amplitude].

The dynamics of the EEG alpha-rhythm asymmetry was studied in 42 subjects before and in the process of verbal activity. Three groups of subjects were identified. 1. The first group was characterized by the dominant activation of the left hemisphere in the background activity and during the first presentations of functional loads. With subsequent presentations the right hemisphere became more activated. 2. In subjects of the second group the right hemisphere was initially more activated. The left hemisphere was more activated only during the first presentations of functional loads. At the final stages, their right hemisphere became again more activated. 3. The third group of subjects was identified by the high level of activation of the right hemisphere in the background activity and during the first presentations of functional loads, and by activation of the right hemisphere at the final stages.

Acoustic Stimulation↗
PubMed1984

Imaging local brain function with emission computed tomography.

Positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) was used to map local cerebral glucose utilization in the study of local cerebral function. This information differs fundamentally from structural assessment by means of computed tomography (CT). In normal human volunteers, the FDG scan was used to determine the cerebral metabolic response to controlled sensory stimulation and the effects of aging. After stroke, regional brain dysfunction is more extensive than had been suspected on the basis of CT scans. Cerebral metabolic patterns are distinctive among depressed and demented elderly patients. The FDG scan appears normal in the depressed patient, studded with multiple metabolic defects in patients with multiple infarct dementia, and in the patients with Alzheimer disease, metabolism is particularly reduced in the parietal cortex, but only slightly reduced in the caudate and thalamus. The caudate is markedly hypometabolic in Huntington disease, even in the absence of caudate atrophy, and possibly may be mildly hypometabolic even before the appearance of symptoms. The interictal FDG scan effectively detects hypometabolic brain zones that are sites of onset for seizures in patients with partial epilepsy, even though these zones usually appear normal on CT scans. The future prospects of PET are discussed.

Adolescent↗
PubMed1990

Relation of EEG alpha background to cognitive function, brain atrophy, and cerebral metabolism in Down's syndrome. Age-specific changes.

We studied 19 young adults (19 to 37 years old) and 9 older patients (42 to 66 years old) with Down's syndrome (DS) and a control group of 13 healthy adults (22 to 38 years old) to investigate the relation of electroencephalographic (EEG) alpha background to cognitive function and cerebral metabolism. Four of the older patients with DS had a history of mental deterioration, disorientation, and memory loss and were demented. Patients and control subjects had EEGs, psychometric testing, quantitative computed tomography, and positron emission tomography with fludeoxyglucose F 18. A "blinded" reader classified the EEGs into two groups--those with normal alpha background or those with abnormal background. All the control subjects, the 13 young adult patients with DS, and the 5 older patients with DS had normal EEG backgrounds. In comparison with the age-matched patients with DS with normal alpha background, older patients with DS with decreased alpha background had dementia, fewer visuospatial skills, decreased attention span, larger third ventricles, and a global decrease in cerebral glucose utilization with parietal hypometabolism. In the young patients with DS, the EEG background did not correlate with psychometric or positron emission tomographic findings, but the third ventricles were significantly larger in those with abnormal EEG background. The young patients with DS, with or without normal EEG background, had positron emission tomographic findings similar to those of the control subjects. The mechanism underlying the abnormal EEG background may be the neuropathologic changes of Alzheimer's disease in older patients with DS and may be cerebral immaturity in younger patients with DS.

Adult↗
PubMed2000

Brain functional reorganization in early blind humans revealed by auditory event-related potentials.

Visually challenged individuals often compensate for their handicap by developing supra-normal abilities in their remaining sensory systems. Here, we examined the scalp distribution of components N1 and P3 of auditory evoked potentials during a sound localization task in four totally blind subjects who had previously shown better performance than sighted subjects. Both N1 and P3 waves peaked at their usual positions while blind and sighted individuals performed the task. However, in blind subjects these two components were also found to be robust over occipital regions while in sighted individuals this pattern was not seen. We conclude that deafferented posterior visual areas in blind individuals are recruited to carry out auditory functions, enabling these individuals to compensate for their lack of vision.

Acoustic Stimulation↗
PubMed1985

[Brain function disorders in 8-year-old children--from a field and consultation population].

The concept of "cerebral dysfunction" was investigated in a several years' epidemiological study involving eight-year-olds in a general population and those seen in a child guidance clinic. Some of the findings differed markedly from what is commonly asserted. The yielded results indicate that brain dysfunctions do not form a single uniform syndrome, that the afflicted children do not show a specific psychopathology and that the disorders can not be traced back to a uniform etiology. The relevance of brain dysfunctions for the child psychiatric morbidity could be proved.

Brain Damage, Chronic↗
PubMed2006

[Sleep and brain function].

Lipocalin-type prostaglandin (PG) D synthase (L-PGDS) catalyzes the isomerization of PGH2, a common precursor of various prostanoids, to produce PGD2, a potent endogenous somnogen. L-PGDS is localized in the leptomeninges, choroid plexus, and oligodendrocytes of the central nervous system. PGD2 is proposed to be a major humoral sleep-inducing factor accumulated in the brain during wakefulness. PGD2 stimulates DP, receptors localized in the basal forebrain and increases the local extracellular concentration of adenosine, which activates A2A receptor-possessing neurons in the basal forebrain and/or ventrolateral preoptic area (VLPO). The intracerebroventricular infusion of PGD2 or adenosine A2A receptor-agonists induces non-REM sleep and increases the expression of fos protein in VLPO. The activation of VLPO neurons is associated with decreased fos expression in the histaminergic tuberomammillary nucleus (TMN), one of the arousal centers. The GABAergic inhibition of TMN is involved in non-REM sleep induction by PGD2 or adenosine A2A receptor-agonists. The neural network between VLPO and TMN is considered to play a key role in the regulation of vigilance states.

Adenosine↗
PubMed2000

[Functional brain imaging: role metabolic coupling between astrocytes and neurons].

Despite the technological sophistication of brain imaging techniques, the precise mechanisms and cell types involved in coupling and in generating metabolic signals are still debated. Recent experimental data on the cellular and molecular mechanisms that underlie the fluorodeoxyglucose (FDG)--based PET imaging point to a critical role of a particular brain cell type, the astrocytes, in coupling neuronal activity to glucose utilization. Indeed, astrocytes possess receptors and re-uptake sites for a variety of neurotransmitters, including glutamate, the predominant excitatory neurotransmitter in the brain. In addition, astrocytic end-feet, which surround capillaries, are enriched in the specific glucose transporter GLUT-1. These features allow astrocytes to "sense" synaptic activity and to couple it with energy metabolism. In vivo and in vitro data support the following functional model: in response to glutamate released by active neurons, glucose is predominantly taken up by astrocytic end-feet; glucose is then metabolized to lactate which provides a preferred energy substrate for neurons. These data support the notion that astrocytes markedly contribute to the FDG-PET signal.

Astrocytes↗
PubMed1991

[Effects of short-term hyperglycemia on the state of brain function in patients with neurological neoplasms].

The paper is concerned with the results of investigation of the effect of short-term hyperglycemia on main cerebral functions in neuro-oncological patients. Clinical and paraclinical control in the course of investigation revealed insignificant and transient changes of the neurological status, ECG and investigated cerebral functions. In a lesser group of patients changes over time were unobserved. Taking into account good tolerance of short-term hyperglycemia and the results of its effective use in general oncology, one can recommend it as a modifier in radiation therapy of brain gliomas. Proceeding from the obtained experimental data on a similar tumor model as well as positive results of the use of short-term hyperglycemia in general oncology, its use appeared to be most effective after tumor irradiation. Taking into account a certain degree of unreliability of the method (catheterization of the subclavicular vein), requiring strict control on the part of medical personnel, the use of short-term hyperglycemia could be effectively implemented during large-fractionated irradiation of brain gliomas.

Adult↗