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PubMed1998

Sperry's concept of mind as an emergent property of brain function and its implications for the future of humankind.

Sperry's proposal that subjective experience plays a major role in brain function and in the emergence of mind, consciousness and human values represent a challenge to behaviorism as the dominant force in psychology. Mind is viewed as an emergent property of the brain, generated from and dependent upon neural activity, but nonetheless separate from it. Macrodeterministic factors result in the evolution of human values, which represent a critical key to world change. Two major conferences resulted from Sperry's challenge to the scientific community. The Trieste Conference led to a 'Declaration of Human Responsibilities', presently under consideration by the United Nations as a corollary to the 'Declaration of Human Rights'. The Japan Conference inspired work toward a Network University of the Green World, in which computer networking will support international communication in areas of environmental concern.

Brain↗

PubMed1998

Functional brain imaging in apraxia.

BACKGROUND: An extensive literature describes structural lesions in apraxia, but few studies have used functional neuroimaging. We used positron emission tomography (PET) to characterize relative cerebral glucose metabolism in a 65-year-old, right-handed woman with progressive decline in ability to manipulate objects, write, and articulate speech. OBJECTIVE: To characterize functional brain organization in apraxia. DESIGN AND METHODS: The patient underwent a neurological examination, neuropsychological testing, magnetic resonance imaging, and fludeoxyglucose F 18 PET. The patient's magnetic resonance image was coregistered to her PET image, which was compared with the PET images of 7 right-handed, healthy controls. Hemispheric regions of interest were normalized by calcrine cortex. RESULTS: Except for apraxia and mild grip weakness, results of the neurological examination were normal. There was ideomotor apraxia of both hands (command, imitation, and object) and buccofacial apraxia. The patient could recognize meaningful gestures performed by the examiner and discriminate between his accurate and awkward pantomime. The magnetic resonance image showed moderate generalized atrophy and mild ischemic changes. Positron emission tomographic scans showed abnormal fludeoxyglucose F 18 uptake in the posterior frontal, supplementary motor, and parietal regions, the left affected more than the right. Focal metabolic deficit was present in the angular gyrus, an area hypothesized to store conceptual knowledge of skilled movement. CONCLUSIONS: Greater parietal than frontal physiological dysfunction and preserved gesture recognition are not consistent with the theory that knowledge of limb praxis is stored in the dominant parietal cortex. Gesture comprehension may be more diffusely distributed.

Aged↗

PubMed2001

Effects of QiGong on brain function.

QiGong is an ancient and widely practiced Chinese meditation exercise. We studied the effects of QiGong on brain function with modern neuromonitoring tools in two subjects. In a male QiGong master (extremely trained practitioner), the technique induced reproducible changes in transcranial Doppler sonography, EEG, stimulus-induced 40 Hz oscillations, and near-infrared spectroscopy findings. Similar effects were seen after the application of multimodal stimuli and when the master concentrated on intense imagined stimuli (e.g. 22.2% increase in mean blood flow velocity (vm) in the posterior cerebral artery, and a simultaneous 23.1% decrease of vm in the middle cerebral artery). Similar effects were seen in the female subject. Neuromonitoring during QiGong appears able to objectify accompanied cerebral modulations surrounding this old Chinese meditation exercise.

Acoustic Stimulation↗

PubMed1999

Normalizing hematocrit in dialysis patients improves brain function.

Recombinant human erythropoietin (rHuEPO) treatment has been shown to improve brain and cognitive function in anemic dialysis patients. Significant debate continues, however, regarding the appropriate target hematocrit (Hct) that will lead to the greatest benefits while considering possible side effects and costs of rHuEPO. Current practice results in an Hct averaging only 31% to 32% in dialysis patients, a level less than that achieved in the initial clinical trials and well less than normal. This study was designed to evaluate dialysis patients at the current practice Hct levels versus normal Hct levels (40% to 45%) to see if improvement in brain function resulted. Twenty patients with end-stage renal disease (ESRD) currently being treated with rHuEPO (mean Hct, 31.6%) were administered additional rHuEPO to reach normal Hct levels (mean, 42. 8%). Electroencephalogram (EEG) frequency analysis showed a significant decrease in EEG slowing at greater Hct values, and the auditory oddball and Continuous Performance Task tasks yielded significant electrode and time-by-electrode effects for P300 amplitude. Changes in P300 latency significantly correlated with increased Hct in the auditory oddball task. These findings suggest that further correction of anemia to normal Hct levels may result in continued improvement in neurocognitive function by improving the ability to sustain attention in easier tasks and by enhancing the ability to recognize, discriminate, and hold stimuli in memory for more difficult tasks.

Anemia↗

PubMed1991

Iron in brain function and dysfunction with emphasis on Parkinson's disease.

Metals such as lead, zinc, copper, aluminum and manganese have been implicated in neuropsychiatric disorders. However, until fairly recently the role of iron in brain function was rather obscure, because little attention was paid to its metabolism in the brain. It is now apparent that maintenance of brain iron homoeostasis is important for the normal functioning of his organ. Most of the studies have been directed towards the cognitive and attentional deficit resulting from nutritional iron deficiency. Evidence so far suggests subsensitivity of striatal dopamine neurotransmission. By contrast the selective increase in free iron in the substantia nigra pars compacta of parkinsonian brains is thought to initiate oxidative stress, from iron-induced liberation of cytotoxic oxygen free radicals. Such radicals are known to promote membrane fluidity, alteration in cellular calcium homoeostasis, lipid peroxidation and finally cell death in systemic organs. Evidence supporting similar processes being responsible for nigrostriatal dopamine neuron degeneration in Parkinson's disease is now becoming available. Such possibilities afford the development of neuroprotective drugs as a means to retard the progression of this disorder. These include other selective monoamine oxidase B inhibitors, iron chelators with the ability to cross the blood-brain barrier, selective calcium channel antagonists and mitochondrial electron transport system protectors.

Anemia, Hypochromic↗

PubMed1992

Functional brain imaging in pediatrics.

With the development of noninvasive tomographic imaging techniques, it is now possible to measure local chemical and physiologic functions in various body organs. Studies of local cerebral glucose metabolism in infants and children using positron emission tomography (PET) have provided important information on human brain functional development and plasticity. The clinical application of functional neuroimaging techniques in the management of pediatric neurologic disorders has yielded encouraging results. In children with intractable epilepsy being considered for surgical intervention, PET is highly sensitive in localizing focal areas of cortical dysplasia, heterotopias, and other migrational defects corresponding to surface electrographic localization of epileptogenic regions. Expanding PET technology provides a new approach that holds great promise in the diagnosis and management of brain disorders in children.

Brain↗

PubMed1988

Effect of tunicamycin on the expression of functional brain neurotransmitter receptors and voltage-operated channels in Xenopus oocytes.

The role of N-glycosylation on the expression of functional brain neurotransmitter receptors and voltage-operated channels was studied by injecting Xenopus oocytes with mRNA from rat brain or chick optic lobe, and culturing them in the presence or absence of tunicamycin, an inhibitor of asparagine linked glycosylation. Electrophysiological recordings were then made to assess the amounts of functional receptors and channels present in the oocyte membrane. The appearance of gamma-aminobutyric acid (GABA) receptors and voltage-activated Na+ channels was profoundly reduced. In contrast, the functional expression of kainate receptors, and voltage-activated K+ and Ca2+ channels was much less affected. Thus, it seems that kainate receptors, and K+ and Ca2+ channels can be expressed and function normally without being glycosylated. On the other hand, GABA receptors and Na+ channels may need to be N-glycosylated in order to function properly, or to ensure their correct insertion into the membrane.

Amino Acids↗

PubMed1992

[Effects of propentofylline (HWA285) on recovery of brain function following total cerebral ischemia (TCI) in dogs].

We examined the effects of a xanthine derivative, propentofylline, on recovery of brain function following TCI in 23 adult mongrel dogs. TCI was produced by clamping ascending aorta with aortoatrial bypass formation. The dogs were divided into 3 groups: preischemic administration (0.3 mg.kg-1.min-1, 30 min), post-ischemic administration (0.5 mg.kg-1.min-1, 6h) and control. The progress of recovery of EEG, respiration, reflexes, motor functions, arousal state and behavior were observed for 7 days after TCI and the latter 5 functions were analysed using neurologic deficit score (NDS). Propentofylline shortened the time necessary for reappearance of EEG after the starting of recirculation but could not improve the NDS.

Animals↗

PubMed2003

[The progress of non-invasive examination of the brain function and child neurology].

During the last 2 decades of the 20th century, various non-invasive examinations of the brain function developed strikingly with the advance of electronics. The examination procedures were tentatively classified into the following generations: the 1st generation: EEG, the 2nd: evoked potentials using signal averaging system, the 3rd: CT and MRI using reconstruction of imaging, 4th: PET, SPECT, fMRI, MEG, MRS and DTI which are categorized in functional imaging, 5th: optic topography combining the functional imaging and time factor. In this article, the outlines of the principle and application of the 4th and 5th generation methods are described. Their application to children requires the development of less invasive and simpler methods. These examination tools still stand on the start line, and will be widely applied to the neurology field in future. Child neurologists should be concerned with the development of their application.

Brain↗

PubMed1998

Is heading a soccer ball injurious to brain function?

With the growing popularity of soccer both in the United States and worldwide, reports of adverse effects of 'heading' on brain function are a source of concern. This article reviews the related research literature on neurologic and neuropsychological findings. Neurologic and neuropsychological abnormalities have been reported in a significant minority of older former professional players in Norway. Purportedly unrelated to age, the most prominent findings were cerebral atrophy and impairment on intelligence test abilities that are particularly vulnerable to brain damage. Also noteworthy in these retired players were persistent physical, cognitive, and emotional complaints consistent with a postconcussive syndrome. Younger amateur players appear to be free of major abnormalities, although some report persistent difficulties with memory and concentration. The severity of these complaints may be related to a history of soccer-related head injuries and not necessarily specific to heading. Research findings specific to heading are not more than suggestive at best, and clarification of the risks of heading a soccer ball awaits more definitive studies.

Biomechanical Phenomena↗

PubMed1998

Cannabis and brain function.

Current literature and practice experience has been reviewed to clarify what is known about the effects of cannabis on brain function, the risk that cannabis use may pose for young people during their adolescence, and risk factors within the individual or their environment that may predispose to long-term abuse and dependence. There is sound evidence that cannabis intoxication has an adverse effect on cognitive function and behaviour, and may, in vulnerable individuals, lead to a psychotic reaction. Regular use may have an adverse effect on learning, with possible mid- to long-term psychological and cognitive impairment. Heavy use may lead to emotional dependence with consequent social and psychological dysfunction. Intervention strategies must go beyond the conventional education and public health measures that appear to have been unsuccessful so far in influencing cannabis use in teenagers. Such strategies may more usefully aim at assessment of risk factors in individuals and groups for dependence on the drug, and the combined and cooperative intervention of parents, schools, health professionals and teenagers themselves.

Adolescent↗

PubMed1997

Alpha oscillations in brain functioning: an integrative theory.

The old concept stating that EEG alpha (10-Hz) activity reflects passive or idling states of the brain is giving way to modern views of 10-Hz oscillations in relation to diverse brain functions comprising sensory, motor, and memory processes: (1) Spontaneous alpha activity is not pure noise as shown by methods of chaos analysis. (2) Evoked alpha oscillations patterns (precisely time-locked to a stimulus; duration approx. 200-300 ms) depend on the modality of stimulation and the recording site. (3) Induced alpha oscillations are initiated by, but not closely time-locked to a stimulus. (4) 10-Hz oscillations are recorded in nervous systems of different complexities, from the human brain to isolated ganglia of invertebrates. The neural origins of 10-Hz oscillations are demonstrated by recordings at the cellular level. (5) Rather than trying to locate a unique alpha generator, it is preferable to assume that a 'diffuse and distributed alpha system' exists. A particular support for this hypothesis is given by stimulus-dependent hippocampal alpha responses in the cat brain. (6) The major physiological meaning of 10-Hz oscillations may be comparable to the putative universal role of gamma responses in brain signaling.

Alpha Rhythm↗

PubMedDate not supplied

Effects of calcium channel blockers on impairment of brain function in senescence-accelerated mice.

The effects of the L-type calcium channel blockers, nicardipine, nimodipine, nilvadipine and amlodipine, on brain dysfunction were examined in senescence-accelerated-prone mice. A disturbed brain function in passive avoidance response, forced swimming, rota-rod and traction tests was observed in senescence-accelerated-prone mice compared to senescence-accelerated-resistant mice. A single oral administration of the four calcium channel blockers tested had little effect on the brain dysfunction in senescence-accelerated-prone mice. In contrast, the daily oral administration of nicardipine (1 and 3 mg/kg), nimodipine (3 mg/kg) and nilvadipine (3 mg/kg), once a day for three weeks, prolonged the shortened latency of step-through in the passive avoidance response and falling time in rota-rod tests. Brain dysfunction in forced swimming and traction tests was not influenced by repeated administration of these blockers. Repeated administration of amlodipine for three weeks in senescence-accelerated-prone mice showed little pharmacological actions in all four tests. Thus, we found that repeated administration of nicardipine, nimodipine and nilvadipine ameliorated the brain dysfunction in these mice. Furthermore, the present study suggests that senescence-accelerated-prone mice can be used as an appropriate model for evaluating the pharmacological effects of calcium channel blockers on brain dysfunction.

Amlodipine↗

PubMed1990

Level of ischemia and brain functions in the Mongolian gerbil in vivo.

The Mongolian gerbil (Meriones unguiculatus) provides a very useful animal model to study the effects of ischemia on brain functions. In this model it is possible to induce two levels of ischemia in the same animal. Thus, monitoring the brain in vivo in real-time will provide meaningful information regarding the development of ischemic injury as well as the follow-up during the recirculation period. The aims of the study were as follows: (1) To elucidate the mechanism behind the development of ischemic depolarization under unilateral and bilateral carotid artery occlusion. (2) To exclude the possibility that removal of the dura mater will affect the results. (3) To correlate the kinetics of the recovery processes to the level of ischemia. We tested the correlation between energy depletion level (evaluated by intramitochondrial NADH redox state) and the development of ischemic depolarization (ID) and vasospasm (evaluated by extracellular K+, DC potential and 366 nm reflectance changes, respectively) under partial and complete ischemia (induced by unilateral or bilateral carotid artery occlusion) using the multiparametric monitoring system (MPA). In 12 out of 32 gerbils monitored by the MPA, the dura mater remained intact, while in the other 20, it was removed very gently before connecting the MPA to the brain. Two types of responses to unilateral carotid artery occlusion were recorded and the gerbils were divided into groups according to the development of the ID. In a third group of 5 gerbils we tested the effect of 1-5 min of bilateral occlusion on the various parameters monitored.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Functional brain imaging in neuropsychiatric disorders of childhood.

This review article presents a summary of the current state-of-the-art of functional brain imaging, with a primary focus on childhood neuropsychiatric disorders. Coverage is emphasized for developments that appear to be of current or potential future importance for the child neurologist and related pediatric specialist, and also from the perspective of the developmental neuroscientist. Emphasis is placed on the modalities of single photon emission computed tomography (SPECT), positron emission tomography (PET), and both "conventional" and "functional" magnetic resonance imaging, (MRI) including reference to the major new radiopharmaceutical and magnetic resonance-based imaging agents and techniques. The fundamental physicochemical processes underlying such studies are outlined, with citation of sources of more detailed information for the interested reader. A variety of imaging studies are reviewed for selected groups of childhood neuropsychiatric disorders, designed to illustrate the achievements and future promise of these imaging modalities. Areas of concentration are suggested for future imaging research in the field of childhood behavioral disorders, where these methods seem critical to improved understanding of pathogenetic mechanisms, as well as development of more effective treatment strategies.

Adolescent↗

PubMed2000

Neurostimulation and functional brain imaging.

Recent advancements in functional neuroimaging have furthered our understanding of the normal and pathological brain. These non-invasive imaging modalities have allowed us to study the human brain in vivo. Concurrently, the revival of neurostimulation in the treatment of pain, movement disorders, and epilepsy has allowed the synergistic combination of these two technologies. Several studies focusing on the use of functional imaging in patients with implanted neurostimulation devices are reviewed. The anticipated roles of these two disciplines are discussed.

Brain↗

PubMedDate not supplied

Magnetic resonance imaging methods for study of human brain function and their application at high magnetic field.

Magnetic resonance imaging (MRI) sequences are finding a new application in the study of human brain function by monitoring localized changes in signal intensity which accompany neuronal activity. These sequences can be sensitized to changes in cerebral blood volume, cerebral blood flow, and blood oxygenation, all of which reflect aspects of neuronal activity in the brain. Many of these experiments benefit from being implemented at a higher magnetic field strength than conventional MRI. An overview of these techniques is presented, and examples of their use are given.

Blood Volume↗

PubMed1996

The mechanism by which exercise modifies brain function.

The effect of exercise on central nervous system function was investigated in relation to the mechanism of calcium-calmodulin-dependent dopamine synthesis in the brain. It is shown here through animal experiments that exercise leads to an increase in the calcium level in the brain. This in turn enhances brain dopamine synthesis, and through this increased dopamine modifies and/or affects brain function, which might induce physiological, behavioral, and psychological changes.

Alcoholic Intoxication↗