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At least 289 records · Page 16Linked to original sources

Genetic feminization of brain structures and changed sexual orientation in male Drosophila.

The neural basis of sexual orientation in Drosophila was studied by the production of males with regionally feminized brains. Such flies express the female form of the sex determination gene transformer in a limited number of neurons under the control of GAL4 enhancer trap inserts. This method facilitated the creation of lines with a stable pattern of feminization. In tests of sexual preferences, flies that were feminized in a portion of the antennal lobes or in a subset of the corpora pedunculata (mushroom bodies) courted both males and females. These two brain structures, both of which are involved in olfactory processing, may function in the recognition of sex-specific pheromones, in the control of sex-specific behaviors, or both.

Animals↗

[Changes in the correlations between the cortical and subcortical brain structures of rats during a shift in the sleep phases].

Studies have been made on the role of correlational relationships between EEG parameters of the brain structures in mechanisms of changes in sleep phases in Wistar rats. Spectral and correlative analysis of the EEG in the visual and sensory-motor cortex, hippocamp and nucleus caudatus was made. The data obtained revealed differences between EEG parameters during sleep--wakefulness cycle. Paradoxical sleep phase differed from slow-sleep phase by weak correlation (+0.39 +/- 0.04) between the visual cortex and subcortical structures. On the contrary, only strong correlation was observed during slow-sleep (+0.73 +/- 0.07) between these structures. During wakefulness, correlation was equal to +0.56 +/- 0.05.

Animals↗

[Effect of electrostimulation of different brain structures on the motor activity of the digestive tract of the cod].

In acute experiments on immobilized unanesthetized cod, the effect of electrical stimulation of different brain structures on electrical activity of smooth muscle of the alimentary tract was investigated. Stimulation of the lateral telencephalon and tectum with trains of square pulses (0.1 - 0.5 mA, 2 msec, 300 Hz) depressed the tonic and peristaltic gastrointestinal motility. Stimulation of the rostral area of cerebellum and medulla oblongata intensified the gastric and intestinal emptying. The effect was found to depend on the level of spontaneous motor activity of the stomach and intestine.

Animals↗

Non-treatment-seeking heavy drinkers: effects of chronic cigarette smoking on brain structure.

We previously reported [Cardenas, V.A., Studholme, C., Meyerhoff, D.J., Song, E., Weiner, M.W., 2005. Chronic active heavy drinking and family history of problem drinking modulate regional brain tissue volumes. Psychiatry Res. 138, 115-130] that non-treatment-seeking, active heavy drinkers (HD) demonstrated smaller regional neocortical gray matter volumes compared to light drinking controls; however, the potential effects of chronic cigarette smoking on regional brain volumes were not addressed. The goal of this retrospective analysis was to determine if chronic smoking affected brain structure in the non-treatment-seeking heavy drinking sample from our earlier report (i.e., Cardenas et al., 2005). Regional volumetric comparisons were made among age-matched smoking HD (n=17), non-smoking HD (n=16), and non-smoking light drinkers (nsLD; n=20) from our original sample. Quantitative volumetric measures of neocortical gray matter (GM), white matter (WM), subcortical structures, and cerebral spinal fluid (CSF) were derived from high-resolution magnetic resonance imaging. Smoking HD demonstrated smaller volumes than nsLD in the frontal, parietal, temporal GM, and for total neocortical GM. Smoking HD also demonstrated smaller temporal and total GM volumes than non-smoking HD. Non-smoking HD and nsLD did not differ significantly on GM volumes. Further, the three groups did not differ on lobar WM, subcortical structures or regional CSF volumes. These retrospective analyses indicate neocortical GM volume reductions in non-treatment-seeking smoking HD, but not in non-smoking HD, which are consistent with our studies in recently detoxified treatment-seeking alcohol-dependent samples.

Adult↗

Influence of hypoxia on the age dependent stimulus-effect-relation of K+-induced dopamine release from rat brain structures.

There is a well defined correlation between stimulus intensity (potassium concentration) and the so-called fractional efflux rate of radio-labelled neurotransmitter from loaded brain structures. K+-induced dopamine release shows an age-dependent parallel shift of the stimulus-effect-relation which obviously reflects quantitative developmental changes during maturation (increasing release) and involution (restricted release) of neuronal structures and functions without modification of involved mechanisms in a qualitative manner. On the other side, mild hypoxia results in quite different, even opposite changes of the stimulus-effect-relation exhibiting the most diverse vulnerability and reactivity of neuronal stimulus-release-coupling at different age.

Aging↗

Effects of nimodipine on multiunit activity of several brain structures following acute global cerebral ischemia-anoxia in cats.

The effects of nimodipine, a 1,4-dihydropyridine calcium channel blocker, on multiunit activity (MUA) of several brain structures were investigated in cats during 6 h immediately following acute global cerebral ischemia-anoxia induced by a 10 min cardiorespiratory arrest (CRA), as well as in cats exposed to sham procedures corresponding to CRA. Four groups of cats were studied: 1) CRA and continuous administration of nimodipine, 1 microgram/kg/min iv during 6 h; 2) CRA and continuous administration of vehicle; 3) sham and continuous administration of nimodipine as in group 1; 4) sham and vehicle as in group 2. MUA and electroencephalogram disappeared during ischemia-anoxia; their progressive recovery occurred throughout the hours following CRA, although 6 h after CRA MUA was still lower than its control prearrest values in all the recorded subcortical structures. Delta-like waves, isolated spikes, and bursts of fast EEG waves occurred during the recovery of EEG activity. Nimodipine inhibited the otherwise increasing MUA in mesencephalic reticular formation, hippocampus and putamen, but not in ventromedial hypothalamus, during the hours following acute global cerebral ischemia-anoxia. Absence of isolated spikes and bursts of fast EEG activity was noted in the EEG of CRA-, nimodipine-treated cats. Nimodipine significantly reduced MUA in hippocampus but not in other cerebral structures in cats of the sham treated group. The results suggest the involvement of 1,4 dihydropyridine sensitive calcium channels in the cellular mechanisms related to neuronal activity after cerebral ischemia-anoxia, and the possible relationship between the effects of nimodipine on MUA and better functional conditions of the central nervous system after acute global cerebral ischemia-anoxia.

Action Potentials↗

Morphological changes in aging brain structures are differentially affected by time-linked environmental influences despite strong genetic stability.

This longitudinal study used the full twin model to estimate change and stability of genetic contributions to morphology of two brain structures, the corpus callosum and lateral ventricles. The 142 subjects were 34 monozygotic (MZ) and 37 dizygotic (DZ) elderly male twin pairs from the National Heart, Lung, and Blood Institute (NHLBI) Twin Study who underwent brain magnetic resonance imaging twice, separated by a 4-year interval. Genetic factors accounted for a substantial portion of individual differences in the size of the corpus callosum and its substructures and of lateral ventricular size. Longitudinal genetic analyses revealed no significant change in the heritability of these structures and no evidence for new genetic variance at Time 2 not present at Time 1. However, both the callosal and ventricular measures showed evidence for new environmental variance at Time 2 not present at Time 1. Confirming a previously posed hypothesis, the phenotypic correlation between absolute change in height of the corpus callosum and absolute change in ventricular volume was significant. Bivariate genetic analysis estimated a significant genetic correlation between the changes in these two structures and the genetic variance in the change of callosal height was entirely due to genes involved in the expansion of ventricles. Genetic stability was present even in old age when brain and other morphological changes can be rapid and highly variable across individuals, inconsistent with an hypothesis that random DNA damage is the cause of aging.

Aged↗

Participation in contact or collision sports in athletes with epilepsy, genetic risk factors, structural brain lesions, or history of craniotomy.

Despite a plethora of guidelines for return to play following mild head injury, a discussion of when and if an athlete should be allowed to participate in contact or collision sports if he or she sustains a structural brain lesion or after a head injury requiring craniotomy is lacking. The structural lesions discussed include arachnoid cyst, Chiari malformation Type I, cavum septum pellucidum, and the presence of ventriculoperitoneal shunts. Issues unique to this population with respect to the possibility of increased risk of head injury are addressed. The population of athletes with epilepsy and certain genetic risk factors is also discussed. Finally, the ability of athletes to participate in contact or collision sports after undergoing craniotomies for traumatic or congenital abnormalities is evaluated. Several known instances of athletes returning to contact sports following craniotomy are also reviewed.

Athletic Injuries↗

The effect of delta-9-tetrahydrocannabinol (delta-9-THC) on the release of nonesterified fatty acids in various brain structures.

There was studied the effect of repeated administration of delta-9-THC (10 mg/kg per os for two days) on the level of nonesterified fatty acids (NEFA) in the brain structures of laboratory rats. Palmitic acid, stearic acid, oleic acid and arachidonic acid were estimated with the help of gas chromatography after preliminary separation by TLC. After administration of delta-9-THC, the levels of NEFA decreased in the brain cortex, the brain stem and most in the hypothalamus. The NEFA decrease after delta-9-THC administration is in harmony with the functional inhibition of CNS, provoked by this substance.

Animals↗

[Changes in brain structure in bipolar affective disorders].

The neurobiological basis of bipolar affective disorders is unknown. However, neuroanatomic circuits of mood regulation have been hypothesized. Neuroimaging revealed volumetric changes of specific brain structures in these circuits. The most prominent abnormality is enlargement of the amygdala. In addition there might be structural changes in the frontal lobe, cerebellum, and pituitary. The findings in bipolar disorder differ from those in unipolar depression and schizophrenia. For further identification of the neurobiological basis of bipolar disorders, structural neuroimaging combined with functional neuroimaging such as magnetic resonance spectroscopy, neuroendocrinological studies, and genetical analyses are required to subgroup patients with bipolar disorder by diagnostic, prognostic, and therapeutic criteria.

Affect↗

Electroconvulsive therapy in patients with late-onset psychoses and structural brain changes.

The authors describe the brain magnetic resonance imaging results and the clinical courses of three patients with late-onset psychoses who were treated with electroconvulsive therapy (ECT). Consistent with previous work, preexisting structural brain changes were present in all three patients. The two patients with the more severe structural changes (lateral ventricular enlargement and large deep-white-matter hyperintensities) failed to respond to ECT. In addition, all three patients had caudate hyperintensities and developed a prolonged interictal ECT-induced delibrium. These observations are also consistent with previous studies that have reported that patients with caudate hyperintensities may be at an increased risk for developing an interictal delirum during a course of ECT.

Aged↗

[Concentration of biogenic amines in different brain structures of the rat adapted to chronic emotional stress].

The level of noradrenaline (NA), dopamine (DA), serotonin (5-OT), and that of 5-oxyindolacetic acid was studied in four brain structures of rats having endured acute or chronic immobilization emotional stress. In stress adapted animals, NA level was normalized in the hypothalamus and increased in the midbrain. DA level was increased in the hypothalamus, the midbrain and the medulla, and 5-OT level was increased in most of the structures studied. During above-mentioned shifts, the animals did not react by additional changes of NA, DA, and 5-OT levels to subsequent immobilizations. Observed rearrangements of turnover of neurotransmitters may be considered as one of the forms of manifestation of chronic emotional stress adaptation mechanisms.

Adaptation, Physiological↗

Monozygotic twins with Asperger syndrome: differences in behaviour reflect variations in brain structure and function.

A pair of monozygotic twins discordant for symptoms of Asperger syndrome was evaluated at the age of 13.45 years using psychometric, morphometric, behavioural, and functional imaging methods. The lower-functioning twin had a smaller brain overall, a smaller right cerebellum, and a disproportionately large left frontal lobe, and manifested almost no differential activation between distractors of high and low-congruence with target visual stimuli. The higher-functioning twin manifested a typically autistic pattern of anterior deactivation and posterior hyperactivation in response to incongruent distractors, overlaid with a typically normal pattern of activation of superior frontal cortex. The morphometric results are consistent with known correlations between brain structure and behaviour in autism, and the physiological results suggest correspondences between structure and function.

Adolescent↗

Immunocytochemical mapping of an RDL-like GABA receptor subunit and of GABA in brain structures related to learning and memory in the cricket Acheta domesticus.

The distribution of putative RDL-like GABA receptors and of gamma-aminobutyric acid (GABA) in the brain of the adult house cricket Acheta domesticus was studied using specific antisera. Special attention was given to brain structures known to be related to learning and memory. The main immunostaining for the RDL-like GABA receptor was observed in mushroom bodies, in particular the upper part of mushroom body peduncle and the two arms of the posterior calyx. Weaker immunostaining was detected in the distal part of the peduncle and in the alpha and beta lobes. The dorso- and ventrolateral protocerebrum neuropils appeared rich in RDL-like GABA receptors. Staining was also detected in the glomeruli of the antennal lobe, as well as in the ellipsoid body of the central complex. Many neurons clustered in groups exhibit GABA-like immunoreactivity. Tracts that were strongly immunostained innervated both the calyces and the lobes of mushroom bodies. The glomeruli of the antennal lobe, the ellipsoid body, as well as neuropils of the dorso- and ventrolateral protocerebrum were also rich in GABA-like immunoreactivity. The data demonstrated a good correlation between the distribution of the GABA-like and of the RDL-like GABA receptor immunoreactivity. The prominent distribution of RDL-like GABA receptor subunits, in particular areas of mushroom bodies and antennal lobes, underlines the importance of inhibitory signals in information processing in these major integrative centers of the insect brain.

Animals↗

RF inhomogeneity compensation in structural brain imaging.

Three-dimensional T(1)-weighted magnetization-prepared rapid gradient-echo (MP-RAGE) sequences with centric phase encoding (PE) in the inner loop provide structural brain images with a high spatial resolution and high tissue contrast. A disadvantage of this sequence type is the susceptibility to inhomogeneities of the radiofrequency (RF) coil, which may result in poor image contrast in some peripheral regions. A special excitation pulse is presented which compensates for these effects in both the head/foot and anterior/posterior directions. This pulse has a duration of only 1.3 ms and is thus compatible with the short repetition times (TRs) required for MP-RAGE imaging. It is shown experimentally that images acquired with the compensation pulse may be segmented without using intensity correction algorithms during data postprocessing.

Artifacts↗

Noxious colorectal distention induced-c-Fos protein in limbic brain structures in the rat.

Colorectal distention is a non-invasive stimulus used to study visceral pain processing in the nervous system. In this study, immunocytochemical labeling for the immediate-early gene, c-Fos, was used to map limbic brain structures involved in processing visceral pain. Rats received noxious colorectal distention while loosely restrained or loose restraint without distention (control). The brains were immunostained and the density of Fos-labeled nuclei within areas of the brain associated with limbic function were examined. Many cortical (cingulate; retrosplenial; insular; perirhinal, entorhinal) and subcortical (periaqueductal gray; locus coeruleus; lateral parabrachial area; paraventricular, anterodorsal and centromedian thalamic nuclei; lateral septal area; dorsomedial hypothalamus; cortical amygdala; subiculum) areas were labeled in the control rats, but significantly more Fos was observed in these areas following noxious colorectal distention (CRD). Additional areas were labeled following CRD but not restraint (e.g. infralimbic and prelimbic cortices; mediodorsal thalamic nucleus; central amygdaloid nucleus). The results show that noxious visceral stimuli result in Fos expression in limbic structures that exceeds that induced by restraint stress, suggesting that different pathways and circuits are recruited by stimuli which can produce similar emotional responses.

Animals↗

Reversal of scopolamine-induced amnesia and alterations in energy metabolism by the nootropic piracetam: implications regarding identification of brain structures involved in consolidation of memory traces.

Pretreatment with scopolamine, 3 mg/kg, prevented the acquisition of a passive avoidance task in rats. These amnesic effects of scopolamine could largely be overcome by treatment with 100 mg/kg of the nootropic drug piracetam. In order to identify the brain structures involved, the effects of these drugs on regional energy metabolism were measured throughout the brain, utilizing Sokoloff's 2-deoxyglucose autoradiographic procedures. Scopolamine, 3 mg/kg, reduced glucose utilization in several areas of the cerebral cortex. These effects were largest in the parietal and temporal cortices. Other areas affected included the sensorimotor and cingulate cortices, the ventral and lateral thalamus, and the dendritic neuropil of the CA1, CA2, and CA3 regions of the hippocampus. The regional depressions in glucose metabolism observed following scopolamine treatment in the rat had some resemblance to depressions in glucose metabolism reported for Alzheimer's disease patients in positron emission tomography studies. Piracetam, 100 mg/kg, did not alter the energy metabolism of any of the 41 brain regions examined. However, this dose of piracetam completely reversed the scopolamine-induced depressions in the hippocampus. Piracetam partially but significantly reversed the scopolamine effects in the cingulate cortex. It is concluded that the data provide support for the hippocampal-cholinergic theory of memory as originally formulated by Meyers and Domino in 1964 and give insight into the mechanisms by which nootropics work.

Amnesia↗

The effect of chronic diazepam and medazepam treatment on the number and affinity of muscarinic receptors in different rat brain structures.

1. The effect of chronic (19-day) treatment with the benzodiazepine tranquilizers diazepam (1 mg/kg/day, i.p.) and medazepam (5 mg/kg/day, i.p.) on the binding characteristics of muscarinic receptors in four rat brain structures: cerebral cortex, striatum, hippocampus and hypothalamus were studied using [3H]l-quinuclidinyl benzylate ([3H]QNB) as radioligand. 2. Diazepam and medazepam treatment caused an overall decrease in muscarinic receptor binding affinity (Kd). 3. The number (Bmax) of muscarinic receptors declined in the hippocampus and striatum and rose in the hypothalamus after both benzodiazepines. The Bmax of muscarinic receptors in the cerebral cortex was increased after diazepam treatment. 4. The changes in the binding characteristics of muscarinic receptors might be due to benzodiazepine-induced occurrence of two populations of muscarinic binding sites: P1 (high affinity, low capacity) and P2 (low affinity, high capacity). 5. The altered brain muscarinic receptor functions after chronic diazepam- or medazepam treatment suggest the role of cholinergic neurotransmission in the mechanism of action of benzodiazepines.

Animals↗