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At least 55 records · Page 3Linked to original sources
PubMed1987

Feedback action and tonic influence of corticosteroids on brain function: a concept arising from the heterogeneity of brain receptor systems.

Two types of corticosteroid receptors can be distinguished in rat brain. The type 1 receptor resembles the kidney mineralocorticoid receptor and has two functional expressions in brain, i.e. type 1 corticosterone (CORT) preferring sites (CR) and mineralocorticoid receptors (MR). The type 2 receptor is similar to the liver glucocorticoid receptor (GR). CORT binds to both CR and GR. The localization, binding specificity, and capacity of the receptor systems have served as criteria to evaluate steroid dependent events in brain biochemistry and behaviour. The GR is widely distributed in neurons and glial cells, with the highest density in frontal brain regions. The GR becomes occupied concomitant with rising plasma CORT levels after stress and as part of the circadian rhythm. The GR mediates the feedback action of CORT on stress-activated brain processes. The CR has its predominant localization in neurons of the septo-hippocampal complex and has a ten-fold higher affinity for CORT than that of the GR. The CR is, at all times of intact adrenocortical secretion, 90% or more occupied by endogenous hormone. The CR mediates a tonic influence exerted with stringent specificity by CORT on hippocampus-associated functions, e.g. cognition, mood, and affect. CORT, via the CR, thus contributes to hippocampus function in interpretation of sensory information, leading to appropriate neuroendocrine and behavioural responses, which are themselves subsequently subject to feedback action via the GR. The MR mediates the mineralocorticoid effect on salt and water balance and its behavioural corollary of salt appetite. The anatomical localization of the MR system is as yet ill-defined, although functional studies suggest circumventricular organs as mineralocorticoid target sites. The CR and the MR have in common the high affinity for mineralocorticoids, but the CR is defined by its exclusive responsiveness to CORT as its agonist. The CR and MR probably represent the same chemical receptor modality (type 1), which is expressed differentially depending on the presence of extravascular corticosteroid binding globulin (CBG) in the vicinity of the receptor. GR capacity is subject to autoregulation. Chronic stress, senescence, and chronic CORT administration reduce GR number, with, as a consequence, a less efficient feedback signal. The CR number seems not to be under the control of corticosteroids, probably since the receptor sites are extensively occupied by endogenous hormones. The CR number displays a circadian rhythm and is reduced during senescence.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex Hormones↗
PubMed1992

Marchiafava-Bignami disease. A case studied by structural and functional brain imaging.

Marchiafava-Bignami disease (MBD) is a rare complication of chronic alcoholism. The clinical features, X-ray, CT and MRI findings are well documented. However, functional brain imaging has not been used in cases of MBD. We used single-photon emission computed tomography (SPECT) to monitor the regional cerebral blood flow in a patient suffering from a acute form of MBD, from which he subsequently recovered. Several abnormalities were found. A more frequent use of functional brain imaging in MBD could improve our knowledge of pathogenesis and prognosis for MBD.

Adult↗
PubMed1975

Memory complaint and impairment in the aged. The effect of depression and altered brain function.

To clarify the role of memory impairment in the aged as a normal or psychopathological phenomenon, 153 persons 50-years-old and over with varying degrees of depression and altered brain function were compared for their complaints about memory and actual performance on a series of memory tests. It was found that while performance varied with altered brain function, complaint was related to level of depression, regardless of performance. Exaggerated memory complaint was considered one manifestation of a general pattern of discrpant reporting of symptoms by depressed persons, and apparently related to an underlying personality factor. The complaint of superiority of remote over recent memory was not substantiated empirically, but was considered part of the pattern of stereotyped language and attitudes characteristic of depressed persons.

Age Factors↗
PubMed1988

Quantitation of complex brain function in children: preliminary evaluation using a nonhuman primate behavioral test battery.

The performance of twenty children (3-11 years of age) in a complex operant test battery (OTB) was evaluated. The operant schedules, or tasks, used in the OTB were identical to those originally designed and currently used to assess complex brain function in nonhuman primate laboratory animals (monkeys). The OTB consisted of five operant tasks: 1) Progressive-Ratio [PR]; 2) Conditioned-Position Responding [CPR]; 3) Temporal Response Differentiation [TRD]; 4) Delayed Matching-to-Sample [DMTS] and 5) Incremental Repeated Acquisition [IRA]. These operant tasks are thought to engender responding indicative of processes associated with: 1) motivation; 2) color and position discrimination; 3) time-perception; 4) short-term memory and attention; and 5) learning, respectively. The parameters for each of the tasks in the OTB were optimized for use in the clinical setting to assess cognitive function in children. In the small population studied, performance in the IRA, DMB and TRD tasks was age related. Of the four 6-yr-olds studied, only those categorized as having either learning disabilities (LD, n = 1) or attention deficit disorders (ADD, n = 2) did not complete the "learning" task. By comparison of human and monkey performance in the OTB, we also hope to validate the use of laboratory animal models in research efforts designed to yield insight into complex human brain function. It is also hoped that assessment of children's performance in the tasks in the OTB will assist in the diagnosis and treatment of certain childhood disorders such as learning disabilities and/or attention deficit disorders.

Animals↗
PubMed1988

Effect of nimodipine upon electroencephalographic vigilance in elderly persons with minor impairment of brain functions.

10 volunteers (61-78 years) with minor impairment of brain function were given placebo, 40 mg and 60 mg nimodipine (Nimotop) in single doses with intervals of 3 medication-free days between medications under double-blind conditions. Consecutive 2-s epochs of a 10-min EEG record (resting conditions) of F3/C3-F4/C4-P3/01-P4/02 were subjected to FFT (Fast Fourier Transform). Using the information given by the 4 leads for each minute of recording the number of epochs which correspond to a stage A or non-A were determined. In order to evaluate subtle effects on electroencephalographic vigilance within stage A, also the anterior-posterior and left-right relations of absolute alpha-power were calculated. Since previous findings suggested that a nimodipine effect can only be demonstrated when individual differences in the baseline-EEG are considered, the subjects were subdivided in equal subgroups according to the number of non-A epochs under placebo. The rationale for this is the finding that in geriatric patients two electroencephalographically distinguishable forms of dissolution can be observed. Under both 40 mg and 60 mg nimodipine the subgroup with a prevalence of non-A epochs (poor alpha-activity) showed a decrease of non-A epochs; the subgroup with a prevalence of A-epochs (abundant alpha-activity), an increase. Opposite results for the two subgroups were also obtained for the left-right relations of alpha-power over the anterior regions. Under 40 mg nimodipine the subgroup with poor alpha-activity showed a shift to the left; the subgroup with abundant alpha-activity to the right. Under 60 mg nimodipine both subgroups showed a shift to the left. The results confirm findings that nimodipine stabilizes electroencephalographic vigilance at a medium level. Moreover they suggest a dose dependence of the effect, i.e., at higher doses nimodipine seems to act as a sedative.

Aged↗
PubMed1991

Structural and functional brain imaging in schizophrenia.

We present an evaluation of the contribution of structural and functional brain imaging to our understanding of schizophrenia. Methodological influences on the validity of the data generated by these new technologies include problems with measurement and clinical and anatomic heterogeneity. These considerations greatly affect the interpretation of the data generated by these technologies. Work in these fields to date, however, has produced strong evidence which suggests that schizophrenia is a disease which involves abnormalities in the structure and function of many brain areas. Structural brain imaging studies of schizophrenia using computed tomography (CT) and magnetic resonance imaging (MRI) are reviewed and their contribution to current theories of the pathogenesis of schizophrenia are discussed. Positron emission tomography (PET) studies of brain metabolic activity and dopamine receptor binding in schizophrenia are summarized and the critical questions raised by these studies are outlined. Future studies in these fields have the potential to yield critical insights into the pathophysiology of schizophrenia; new directions for studies of schizophrenia using these technologies are identified.

Brain↗
PubMed1990

Correlation methods for the centering, rotation, and alignment of functional brain images.

Simple methods are described using correlation analysis to rotate functional brain images to a standard vertical orientation, identify the antero-posterior centerline, and align multiple images from the same brain level. Image rotation and centering are performed by determining the angle of rotation and centerline coordinate that result in maximal left-right correlation. Testing of this method on sets of multiple images acquired simultaneously through different brain levels suggests that the optimal rotation can be determined within 1 degree and the centerline within 0.3 mm. Spatial alignment of two or more images from the same brain level of a single subject is accomplished by finding the translation and rotation that yield the highest correlation between the images. Testing of the alignment method on sets of simultaneously acquired images at multiple brain levels suggests that the optimal translation can be determined within 0.45-0.69 mm and the optimal rotation within 0.8 degrees. These methods are completely objective and can easily be automated.

Aged↗
PubMed1991

[5-year follow-up study of brain function in the healthy aged--study of the relationship between environmental factors and results of psychiatric examinations].

In order to investigate the relationship between environmental factors and results of psychiatric examinations, a questionnaire survey studying these factors and neurophysiological examinations (electroncephalography (EEG), somatosensory evoked response (SER) and contingent negative variation (CNV)), as well as clinical neuropsychiatric examinations and intelligence scale (Hasegawa's dementia rating scale (HDRS) and Kohs's blocking design test (KBDT)), were performed on 41 healthy aged (61-80 years old) who were participants in programs of Osaka Prefectural Center for the elderly. Initial examinations were conducted in 1983 and the second in 1988 on the same subjects for the purpose of measuring the aging process over 5 years with regard to brain function. A total of 29 subjects, for a participation rate of 82.9% (excluding deceased and those who moved away from the area), attended the second examination. The results are summarized as follows. 1. When environmental factors were compared for 1983 and 1988, a reduction in participation in social activity was observed in some of the aged in 1988, although differences in their daily living situations were unchanged. 2. The mean scores of HDRS and KBDT were 31.9, 98.6 in 1983 and 30.2, 94.6 in 1988 respectively, with only 2 subjects showing considerable decline of intelligence. 3. With regard to the neurophysiological examinations, the number of subjects with peak latencies of SER that were abnormally prolonged increased in 1988, while there was little difference in their EEGs between 1983 and 1988. 4. From these results, it appears that the relation between declines in brain function and environmental factors, involves multiple factors that will require further study.

Age Factors↗
PubMed1976

Cerebral blood flow and brain function during hypotension and shock.

In conclusion, the reviewed results clearly suggest that vital functions of the brain -in spite of the well-developed autoregulatory mechanisms-are impaired during long-lasting hypovolemic and other shock conditions. The insufficiency of the cerebrocortical and hypothalamic regulatory mechanisms can contribute to the development of the irreversible shock. In other words, failure of the body suffering from shock to restore the homeostatic equilibrium can be attributed to the inadequacy of the central nervous servocontrol system. According to the available results, the regional cerebral microcirculatory defect develops through sludge formation. The unevenly distributed local brain damage could be the background of the functional impairment. The focal appearance suggest that, in addition to generalized (bloody borne) changes, local factors play an important role in the production of patchy ischemic areas in the brain.

Acetylcholine↗
PubMed1991

Tc-99m HMPAO SPECT analysis of neuroleptic effects on regional brain function.

This report describes a new approach to the evaluation of neuroleptic effects on regional brain function. Using Tc-99m HMPAO SPECT imaging, consecutive brain perfusion studies before and after acute haloperidol administration were performed on three schizophrenic patients and two normal volunteers. The antipsychotic drug ameliorated the hypoactivity in the frontal lobe and suppressed the hyperactivity in the temporo-occipito-parietal lobe selectively in the dominant hemisphere in the schizophrenic patients. It did not exert a significant influence on the brain perfusion pattern in normal volunteers. This nuclear medicine technique seems to be useful for the evaluation of drug effects in psychiatric diseases.

Adult↗
PubMed1988

Complex brain function in monkeys as a baseline for studying the effects of exogenous compounds.

We have examined the population characteristics of a group of 69 monkey subjects performing in a complex operant test battery designed to generate behaviors indicative of specific brain functions. These functions include learning, short-term memory and attention, time perception, position and color discrimination and motivation. Performance by a subject in one of these operant tasks is not necessarily correlated with or predictive of performance in the other tasks, indicating that the tests in the battery are monitoring the functions of different brain systems. Additionally, as demonstrated by challenging a few of the animals with intravenous delta-9-tetrahydrocannabinol, we have shown that the performances in the various components of the test battery are differentially sensitive to disruption by exogenous compounds.

Animals↗
PubMed1985

[Effect of intravenous administration of diltiazem on cerebral blood flow and brain function].

The effect of intravenous administration of diltiazem on cerebral circulation and brain function were studied in animals. Diltiazem, at a dose of 150 micrograms/kg BW, was administered intravenously over a period of 5 minutes beginning 30 minutes after ligation of the right brachiocephalic artery in 9 cats in order to investigate its effects in the acute stage of cerebral ischemia. In 5 animals, mean arterial blood pressure was recorded and blood flow in the basilar artery was measured transdurally by use of an ultrasonic Doppler flow-meter. Mean arterial blood pressure began to elevate immediately after ligation of the right brachiocephalic artery, but the degree of elevation was minimal. It began to fall during diltiazem injection and returned to the preadministration value 30 minutes after injection. Basilar artery flow decreased slightly during injection of diltiazem, but began to increase after completion of injection. The increase relative to the preadministration value was 62 +/- 31% 10 minutes after injection, 88 +/- 38% 20 minutes after, and 24 +/- 53% 30 minutes after. The short latency somatosensory evoked potentials (short latency SEP) recorded in the other 2 animals showed no noticeable change either in amplitude or latency during the same procedures. In 1 of 2 animals in which brainstem auditory evoked potentials (BAEP) were monitored, the latency of peak IV increased after ligation of the right brachiocephalic artery, and decreased 20 minutes after injection of diltiazem.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Concussive methods of pre-slaughter stunning in sheep: assessment of brain function using cortical evoked responses.

Averaged cortical evoked responses were used to evaluate brain function in anaesthetised sheep. Effects on both evoked somatosensory responses (SERs) and visual evoked responses (VERs) were examined. Following capitive bolt stunning, SERs and VERs were abolished instantaneously and did not reappear for the duration of the experiment. Similar results were found when animals were shot while conscious. It was concluded that captive bolt stunning in sheep produces an immediate, profound and long lasting brain failure and is therefore an effective preslaughter stunning method.

Animals↗
PubMedDate not supplied

[The effect of a high-intensity radiation exposure on the brain function of monkeys. The postradiation changes in brain bioelectrical activity].

In experiments with Macaca fascicularis it has been found that changes in the total bioelectric activity of the brain within the EEG range that occur during the first 60 min following whole-body irradiation with a dose of 45 Gy (6.5 Gy/s) are interrelated with the dynamics of nervous and psychic activity of the exposed animals, exhibit a definite stereotype of their development (disorganization of rhythms: generalized synchronization of biopotentials; and development of synchronous processes), and coincide in time with the main stages of the development of the clinical picture of the acute postirradiation period (noncoordinated stimulation, sopor or coma, and partial recovery).

Animals↗
PubMed1989

Noninvasive study of critical thresholds of intracranial pressure and cerebral perfusion pressure for cerebral circulation and brain function.

To ascertain the critical thresholds of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) for cerebral circulation and brain function, the extra- and intracranial haemodynamics and electrical brain responses were evaluated noninvasively with Doppler ultrasonography and multimodality evoked potentials (MEP's) in 50 patients with severe head injury. Both extra- and intracranial blood flow velocities changed monotonically depending on the changes in ICP and CPP. They were decreased when ICP increased to 20-30 mmHg and when CPP decreased to 40-50 mmHg. The changes in elasticity index of the pulse wave of the common carotid artery was proportional to those of blood flow velocities. The frequency and degree of abnormalities of MEP's were proportionally increased with the rise of ICP and reduction of CPP. When ICP increased to higher than 31 mmHg, MEP's were classified as moderately or severely abnormal in more than 76% of the recordings. These results indicate that noninvasive study by use of Doppler ultrasonography and MEP's can provide valuable information on critical brain ischaemia and brain dysfunction in patients with acute intracranial hypertension.

Adolescent↗
PubMed1975

Computerized Electroencephalogram. A model of understanding the brain function in childhood psychosis and its treatment.

Computer analysis of the electroencephalogram (CEEG) in psychotic children before and after pharmacotherapy, normal children of schizophrenic mothers, and matched normal children of normal parents indicated significant intergroup differences. The psychotic children had more slow, as well as very fast, EEG waves. With drug therapy the EEG showed a partial "normalization," as fast EEG activity decreased. The EEG and auditory evoked potential of children of schizophrenic mothers were strikingly similar to those of psychotic children and schizophrenic adults, with significant decreases of the average EEG amplitude and the evoked potential latencies. Psychotic children were distinctly differentiated from the normal children by discriminant function analysis of the EEG and EP. Quantitative analysis of brain functions in the mentally ill can help determine the neurophysiological correlates of behavior, a more scientific diagnostic classification, prognosis, and selection of therapy.

Acoustic Stimulation↗