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At least 1,099 records · Page 61Linked to original sources
PubMed1998

[Systemic organization of brain functions: key role of results action acceptor].

The paper presents general principles of organization of human psychic functions on the basis of P.K.Anokhin's theory of functional systems. The peculiarities of forming psychic activity are analyzed on the information basis of systemic activity of brain. The key role in management of psychic activity belongs to foreseeing of required results, i.e. the acceptor of action's results. Holographic and molecular mechanisms of forming informative engram of acceptor of action's results are considered.

Animals↗
PubMed2002

Limbic seizures induce P-glycoprotein in rodent brain: functional implications for pharmacoresistance.

The causes and mechanisms underlying multidrug resistance (MDR) in epilepsy are still elusive and may depend on inadequate drug concentration in crucial brain areas. We studied whether limbic seizures or anticonvulsant drug treatments in rodents enhance the brain expression of the MDR gene (mdr) encoding a permeability glycoprotein (P-gp) involved in MDR to various cancer chemotherapeutic agents. We also investigated whether changes in P-gp levels affect anticonvulsant drug concentrations in the brain. Mdr mRNA measured by RT-PCR increased by 85% on average in the mouse hippocampus 3-24 hr after kainic acid-induced limbic seizures, returning to control levels by 72 hr. Treatment with therapeutic doses of phenytoin or carbamazepine for 7 d did not change mdr mRNA expression in the mouse hippocampus 1-72 hr after the last drug administration. Six hours after seizures, the brain/plasma ratio of phenytoin was reduced by 30% and its extracellular concentration estimated by microdialysis was increased by twofold compared with control mice. Knock-out mice (mdr1a/b -/-) lacking P-gp protein showed a 46% increase in phenytoin concentrations in the hippocampus 1 and 4 hr after injection compared with wild-type mice. A significant 23% increase was found in the cerebellum at 1 hr and in the cortex at 4 hr. Carbamazepine concentrations were measurable in the hippocampus at 3 hr in mdr1a/b -/- mice, whereas they were undetectable at the same time interval in wild-type mice. In rats having spontaneous seizures 3 months after electrically induced status epilepticus, mdr1 mRNA levels were enhanced by 1.8-fold and fivefold on average in the hippocampus and entorhinal cortex, respectively. Thus, changes in P-gp mRNA levels occur in limbic areas after both acute and chronic epileptic activity. P-gp alterations significantly affect antiepileptic drugs concentrations in the brain, suggesting that seizure-induced mdr mRNA expression contributes to MDR in epilepsy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

A positron emission tomography study of short- and long-term treatment effects on functional brain activation in adults who stutter.

UNLABELLED: Previous studies have shown that fluency-inducing techniques, such as choral speech, result in changes in neural activation as measured by functional neuroimaging. In the present study, positron emission tomography was used to investigate the effects of intensive behavioural treatment, followed by a 1-year maintenance program, on the pattern of cortical and subcortical activation in stuttering adults during silent and oral reading of single words. The results indicate changes in activation lateralisation, as well as a general reduction in over-activation, especially in the motor cortex, following treatment. The results are discussed in light of previous functional imaging studies with stuttering adults. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to describe the: (1) use of functional neuroimaging PET in the study of stuttering; (2) differences in neural activation between stuttering and non-stuttering adults; and (3) effects of behavioural fluency treatment on cortical and subcortical activations in stuttering speakers.

Adult↗
PubMed1976

Differential association between chronic cannabis use and brain function deficits.

To summarize, 12 objective tests that generated 16 test variables were administered to 850 male regular cannabis users and 839 nonusers. The tests were designed to assess various modalities, including speed of psychomotor performance, distance estimation, time estimation, immediate memory, and visuomotor coordination. Most of the test variables differentiated significantly between consumers and controls. At the same time, a significant second-order interaction emerged in most cases. This interaction meant that, under certain conditions that relate to the two dimensions "literacy-illiteracy" and/or "urbanism-ruralism," the superiority of controls over cannabis users became impressive, whereas under other conditions it almost disappeared. To account for this complex pattern of results, a working hypothesis was presented to the effect that "other conditions being equal, the lower the nondrug level of proficiency on tests of cognitive and psychomotor performance the smaller the size of function deficit associated with drug usage." For an empirical examination of the hypothesis, six predictions were formulated. Three predictions defined specific relationships between level of performance, on one hand, and each of three organismic variables, on the other: literacy, urbanism, and age. The remaining predictions delineated relationships to be expected between size of function deficit and the three organismic variables. All our predictions were confirmed, showing less function impairment to be contingent with cannabis usage among the illiterates, rurals, and older subjects. Level of cortical arousal was suggested as the central process associated with the three organismic variables. Because the version of our working hypothesis was formulated with reference to chronic material, the possibility of a transposition of the paradign to research on the acute effects of the drug was discussed. The suggestion was made that our working hypothesis, in either version, is capable of establishing genuine integration between reports that present conflicting results on possible function deficits contingent with cannabis consumption.

Adolescent↗
PubMed1981

Individually reared rats: alteration in noradrenergic brain functions.

The influence of social isolation in rats on postsynaptic alpha 1- and beta-adrenergic receptors, on the cAMP generating system and on the presynaptic uptake mechanism in the central noradrenergic system was examined in different brain regions. Rearing rats in isolation from the 19th day of life for 12 weeks leads in all regions to a general tendency for a reduction in 3H-DHA binding, to an enhanced 3H-WB4101 binding and to a decreased responsiveness of the noradrenaline sensitive cAMP generating system. These changes reach significant only in the pons-medulla-thalamus region. Isolated rats showed an increased synaptosomal uptake of noradrenaline, most pronounced and significant in the hypothalamus. Our data provide further support for a disturbance in central noradrenergic function in isolated rats.

Adenylyl Cyclases↗
PubMed1984

Testing a theory of brain function by computer methods. IV. Comparing spatial and temporal order in the two cerebral hemispheres.

Continuing with a plan for overall testing of the timing and sequencing of brain processes, further testing techniques are introduced for probing a normal adult's short-term central processes, especially those which are employed in reading a short digit span. The tests are administered by means of a personal computer and can provide information on the individual subject's characteristic sequencing and timing of particular central processes. In a subject whose first language is read from left to right, the presented tests reported in this paper can reveal an interesting asymmetry. A temporal display of digits in the right visual field is correctly perceived more readily than in the left. Conversely, a brief, spatial display of digits in the left visual field is correctly reported more often than in the right. It is suggested, therefore, that there are individuals whose left hemisphere is superior in handling a temporal sequence of digits while the right hemisphere is superior in handling a spatial display of digits.

Adult↗