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PubMed1980

Lateral eye movement and handedness as measures of functional brain asymmetry in learning disability.

Evidence is presented which suggests that learning disability is related to lateral asymmetry. Significant differences were found in lateral eye movement and handedness between a learning disabled group and a control group of normal learners. Left lateral eye movement and right handedness was the predominant pattern exhibited in learning disability. These results support Day's notion that left lateral eye movement is associated with educational difficulties. They also provide evidence concerning Orton's hypothesis that mixed cerebral dominance characterizes the learning disabled.

Child↗

PubMedDate not supplied

[The significance of multiple neuromediator activity in supporting integrative brain functions].

Properties were studied of reactions of neural cells of the sensorimotor cortical area to locally microionophoretically administered l-glutamate, acetylcholine, norepinephrine and gamma-aminobutyric acid. It is shown that neuronal reactions to the action of the above-mentioned transmitters differ both in direction of change in the impulse activity frequency and in temporal offracteristics (latency and duration of after-effect). It is substantiated that due to the specificity of temporal ranges of action of the transmitter on neural cells, the possibility of effective interaction and temporal coding of heterofunctional information is provided.

Acetylcholine↗

PubMed2004

Using eye movements to assess brain function in mice.

Examining eye movements is an important part of the neurological evaluation of humans; the distribution of the neural circuits that control these movements is such that they are disrupted--often in highly characteristic fashions--by many disease processes. Technical advances have made it possible to measure accurately the eye movements of mice, so it is now possible to use the detective power of eye movement recording to characterize neurological dysfunction in genetically altered strains. Here we introduce analytical tools used in ocular motor research and demonstrate their ability to reveal disorders of the visual pathways, inner ear, and cerebellum.

Animals↗

PubMed1988

[Preoperative diagnosis: the Wada test with SPECT control for localizing brain function in therapy-refractory epilepsy].

Extensive diagnostic measures are necessary to clarify the indication for surgery in patients suffering from epilepsy that is refractory to treatment. Within the overall framework of neuropsychological diagnosis we conducted the Wada test, injecting 200 mg (or 3 mg/kg body weight) of sodium amytal on different days, in each case into the left or right internal carotid artery. This results in a 3-5 minute anaesthesia of the relevant hemisphere. By means of a neuropsychological short test it is possible to determine the performance of the non-blocked hemisphere. The extent of the blocking is also determined by simultaneous i.v. injection of HM-PAO (hexamethyl propylene amine oxime) labelled with 99m Tc, the uptake of which by various cerebral regions is visualised via SPECT. The Wada test supplies information on the lateralisation of cognitive functions (speech, memory etc.) whereas the SPECT examination enables additional determinations not only of processes that must be characterised as diaschisis, but also on the extent of blocking of a hemisphere. The results supply clues to expected postoperative cognitive deficits and thus enable a differentiated assessment of the indication for surgery. This is discussed on the basis of two clinical cases.

Adult↗

PubMed1983

Brain function estimated from the ratio of glutamine to homocarnosine levels in cerebrospinal fluid.

The ratio of glutamine to homocarnosine (G/H ratio) in CSF of children with meningeal pathology or convulsions was measured and the following results were obtained. 1. The mean G/H ratio of normal subjects was 83.0 +/- 41.4. 2. The mean G/H ratios of the patients with bacterial meningitis and meningeal leukemia were 115.9 +/- 81.9 and 115.2 +/- 49.2, respectively. Significant differences were found between those in normal subjects and these diseases. 3. The mean G/H ratio of the patients with viral meningitis was 80.0 +/- 35.1 and no significant difference was found between normal subjects and these patients. 4. The mean G/H ratios in the patients with controlled versus uncontrolled epilepsy were 130.9 +/- 67.1 and 74.8 +/- 49.4, respectively. A significant difference was found between normal subjects and the patients with controlled epilepsy. 5. The mean G/H ratio in the patients with febrile convulsions was 46.5 +/- 6.3. A significant difference was found between normal subjects and these patients. These data suggest that a high G/H ratio in CSF may indicate the excited state of the brain.

Bacterial Infections↗

PubMed2003

Nutrition, brain function and cognitive performance.

Military interest in the effects of nutritional factors on cognitive function has stimulated considerable research on a variety of food constituents. This paper will review the research on the amino acids tryptophan and tyrosine, caffeine and carbohydrate. It will focus on research that addresses the potential utility of these compounds in military applications, particularly the acute, as opposed to chronic, effects of these substances on cognitive functions such as alertness, vigilance and resistance to stress. Caffeine, the most intensively studied food constituent, has unequivocal beneficial effects on vigilance, and in sleep deprived individuals it enhances other cognitive functions as well. Tryptophan, although it clearly has sedative-like properties, has not been extensively studied by military laboratories for use as a hypnotic, due to safety concerns. Tyrosine has been examined in animal models and human studies, and appears to prevent the substantial decline in various aspects of cognitive performance and mood associated with many kinds of acute stress. Carbohydrate supplementation appears to enhance cognitive performance in soldiers engaged in sustained, intense physical activities that expend high levels of energy.

Adult↗

PubMed2000

Neuronal nicotinic receptors, important new players in brain function.

Acetylcholine receptors are cationic channels whose opening is controlled by acetylcholine. They are key molecules in the cholinergic nicotinic transmission in a number of areas of the central and peripheral nervous system. Because of the structural complexity, given by the numerous subunits that forms these receptors, they have different pharmacological and biophysical properties. Here we give a brief account of the known and consolidated data regarding neuronal nicotinic receptors, as as an introduction to the articles reported in this issue, in order to allow readers who are not familiar with the field to place the detailed information in the right context.

Brain↗

PubMed1992

A nonlinear approach to brain function: deterministic chaos and sleep EEG.

In order to perform a nonlinear dimensional analysis of the sleep electroencephalogram (EEG), we applied an algorithm proposed by Grassberger and Procaccia to calculate the correlation dimension D2 of different sleep stages under Lorazepam medication versus placebo. This correlation dimension characterizes the dynamics of the sleep EEG and it estimates the degrees of freedom of the signal under study. We demonstrate that slow-wave sleep depicts a much smaller dimensionality than light or rapid eye movement (REM) sleep, and that Lorazepam does not alter the EEG's dimensionality except in stage II and REM.

Adult↗

PubMed1975

Three principles of brain function and structure.

A large part of the presently available data in the physiology and anatomy of the nervous system is found to be consistent with three comparatively simple principles. Phrased in the terminology introduced in the paper, the first of these expresses the assumption of specificity of neuron response, the second states the biological equivalent of a maximum principle believed to govern the formation and modication of interneuronal connectivity, and the third describes the probable role of genetically determined gross anatomy in securing the groundwork for developing neurospecificity. A number of remarks are included, and an extensive discussion of the evidence behind the principles.

Action Potentials↗

PubMed1988

Slow channel inhibitor effects on brain function: tolerance to severe hypoxia in the rat.

1. The protective effects of ten slow channel inhibitor drugs against severe progressive hypoxia were investigated in rats breathing spontaneously during light anaesthesia. Respiration, heart rate, electrocorticogram (ECoG) and/or electroencephalogram (EEG) were recorded. 2. Tolerance times were monitored from hypoxia onset until cessation of respiration, ECoG, EEG synchronization, and 'background-EEG'. Drugs were administered i.v. 5 min before the onset of hypoxia. 3. Verapamil, gallopamil, and nimodipine resulted in a significant increase of tolerance times; fendiline and bepridil showed a small increase (not significant); bencyclan and prenylamine were ineffective; cinnarizine and diltiazem slightly reduced tolerance times as did flunarizine at low doses. 4. At protective doses, verapamil, gallopamil, and nimodipine significantly raised the respiration rate but had little or no cardiac depressor effects. Bencyclan showed ventilatory drive but cardiocirculatory depression. A clear-cut ventilatory drive did not occur with the other ineffective slow channel inhibitors. 5. It is suggested that the protective actions observed were not due to slow channel inhibition per se, nor to spasmolytic potency or increased cerebral blood flow. Ventilatory drive associated with other cardiopulmonary actions which secondarily raise the brain oxygen supply are likely to be responsible for this effect.

Animals↗

PubMed2001

Physiological roles for the neurosteroid allopregnanolone in the modulation of brain function during pregnancy and parturition.

Allopregnanolone is a well-established allosteric modulator of the GABAA receptor but its physiological roles within the nervous system remain unclear. Derived principally from circulating progesterone, allopregnanolone achieves its highest concentrations within the nervous system during late pregnancy and recent studies have now begun to elucidate its roles at this time in the rat. At the molecular level it is clear that the regulation of GABAA receptor subunit gene expression by progesterone and its derivatives occurs in a subunit- and a neuron-specific manner and that both progesterone and allopregnanolone are involved. At the cellular level, the increasing concentrations of allopregnanolone with advancing pregnancy can be shown to have important physiological actions in repressing the electrical activity of specific neuronal phenotypes such as the magnocellular oxytocin neurons. The marked fall in progesterone and allopregnanolone concentrations prior to parturition equally appears to have a substantial impact upon GABAA receptor signaling in the hippocampus, frontal cortex and oxytocin neurons. Together, studies at a basic level suggest that the rise and fall in allopregnanolone concentrations during pregnancy are likely to exert a powerful regulatory influence upon neurotransmission in a variety of brain networks. The temporal correlation between these events and the observed cognitive, psychiatric and physiological changes associated with pregnancy and the peri-partum period in humans is striking and warrants close attention.

Animals↗

PubMed1987

Recovery of brain function after ischaemia.

Experimental evidence has recently suggested that early reperfusion following at least focal cerebral ischaemia is accompanied by a return of function which has apparently been suspended during the ischaemic period. The experimental evidence for this is presented. Clinical correlates of this reversible ischaemia sometimes referred to as "penumbral ischaemia" are well known in relation to aneurysm surgery. Several examples are presented in this paper. It is also clear that less easily documented and verifiable recovery from long-term ischaemia may occur in neurosurgery and in interesting case suggestive of this is presented. It involved a middle cerebral occlusion which occurred during the excision of a large meningioma.

Adult↗

PubMedDate not supplied

[The dynamics of the cerebral circulation and of brain functional activity in patients with initial atherosclerotic encephalopathy under the influence of a single intravenous administration of sermion].

The efficacy of sermion was studied in 41 patients of the middle and elderly ages. The reactive changes in the parameters of the cerebral circulation (the frontomastoidal RhEG), total hemodynamics, frequency-integration characteristics of EEG and visual evoked potentials at the administration of 2 mg and 4 mg of sermion were shown. There are given recommendations for the differential approach to the choice of the drug doses in the elderly persons taking into consideration the parameters of the background reactivity of the CNS and the state of vascular regulation.

Aged↗

PubMed2003

Estrogens: protective or risk factors in brain function?

Over the past century, the average lifespan of women has increased from 50 to over 80 years, but the age of the menopause has remained fixed at 51 years. This "change of life" is marked by a dramatic and permanent decrease in circulating levels of ovarian estrogens. Therefore, more women will live a greater proportion of their lives in a chronic hypoestrogenic state. Ovarian steroid hormones are pleiotropic and have multiple, diverse, and possibly opposing actions in different contexts. In light of recent reports of the possible health risks of hormone replacement therapy (HRT) on several different physiological systems, the question of whether estrogens are protective or risk factors must be carefully re-evaluated.

Animals↗

PubMed1992

[The action on brain functions in white rats of the immunostimulant Freund's complete adjuvant].

The effect of immunostimulator--Freund's adjuvant complete on the nociception and learning of white rats using food-obtaining and avoidance of electric shock techniques has been studied. It has been shown that the adjuvant in doses for active immunization causes itself the expressed changes in animal behaviour. The adjuvant's injections significantly increases the learning ability of animals both with negative and positive reinforcement as compared with control one. The changes in pain severity is marked only for dose 0.2 ml. The nonspecific action of adjuvant should be taken into account in researches which use the active immunisation method.

Animals↗

PubMed1982

Longitudinal study of brain function and depletion of iron stores in individual subjects.

Seven men living in a controlled research unit showed decrements in iron stores due to repeated phlebotomy. For each subject, weekly measures of cognitive task performance, electroencephalographic (EEG) power and Event-Related Potentials (ERPs) were examined in relation to serum ferritin level. No reliable relationships of ferritin level to cognitive performance ability were observed. Some EEG findings appeared similar to previous observations on EEG data and iron status in cross-sectional research. For four of the seven subjects, asymmetries of EEG power in the occipital electrodes appeared related to the decline in iron status over time.

Adult↗

PubMedDate not supplied

"Follow-up" method for processing of brain function MR images.

FMRI with standard 1.5 T scanners requires adapted algorithms because the time course of intensity signal showed a non-linearity of the baseline. The protocol contains sequential images covering periods of rest followed periods of stimulation. The images of each period of rest and stimulation were averaged, offering a series of averaged images. From this series, we conserved only the pixels which presented the alternated variations corresponding to the temporal pattern of the paradigm. A colour scale was used to present the average percentage of variations of each pixel selected. We have performed activation paradigms with a classical motor protocol. This simple "follow-up" method appears effective for the identification of activated areas.

Algorithms↗

PubMed2000

[A neuropsychological and functional brain imaging study of visuo-imitative apraxia].

We describe the case of a 58-years-old right-handed women suffering from an occipital-parietal lesion. The administration of a cognitively based assessment tool for limb praxis (Batterie d'Evaluation des Praxies, B.E.P., Peigneux and Van der Linden, 1998) demonstrated bilateral visuo-imitative apraxia. Gesture production was mainly characterised by spatial, errors, and imitation of meaningful gestures was worse than their pantomime on verbal command. Moreover, the imitation of meaningless gestures and their reproduction on a manikin were worse than imitation of their matched meaningful gestures. In a cognitive perspective, adapted from the Rothi et al. (1997) and Goldenberg (1995) contributions to our understanding of limb praxis, this configuration of performance suggests deficits occurring at multiple levels. On one hand, it suggests either access difficulties or alteration of the output praxicon, i.e., the lexicon for visuo-kinesthetic engrams of meaningful gestures. On the other hand, the simultaneous deficit for meaningless gesture reproduction on the subject's own body and on a manikin favors an alteration of the structural descriptions of the human body (i.e., human body knowledge), underlying the mental transposition processes occurring between the visual analysis of a meaningless gestural configuration and its effective reproduction on oneself or on a manikin, thus contradicting the classic view of a direct pathway linking visual analysis and motor planning in meaningless gesture imitation. Finally, due to the output praxicon deficit, imitation of meaningful gestures is partly processed in the same way as meaningless gestures (also impaired in this case), leading to an interference effect between both degraded memory-based and visually-transposed traces, which account for imitation of meaningful gestures being worse than their pantomime on verbal command. We also assess regional cerebral metabolism using positron emission tomography (PET). Comparison with 41 healthy subjects (SPM96) demonstrated a statistically significant hypometabolism in the left intraparietal sulcus and superior parietal lobule, and in the right dorsal prestriate cortex. These results, together with a review of the other studies of visuo-imitative apraxia, suggest that the left intraparietal sulcus may be associated with access or integration of information from the output praxicon. The left superior parietal and the right dorsal prestriate deficits functionally impaired a bilateral dorsal network implied in the mental transformations of the body, thus suggesting that these mental transformations are underlined by knowledge of the human body, which may subsequently explain the deficit for the reproduction of meaningless and meaningful configurations.

Aged↗