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At least 307 records · Page 17Linked to original sources
PubMed1986

[Enzyme histochemical demonstration of sodium-dependent glutamate uptake in glutamatergic brain structures in the rat].

Using a special tetrazolium salt technique, a striking correlation was observed between Na+ concentration of the incubation medium and the activity of glutamate dehydrogenase (GDH) in glutamatergic neuropil areas of the hippocampal formation, cerebellum, and other brain regions. Na+ concentration of 130 to 150 mmol/l caused maximal formazan production. The histochemical enzyme reaction in neuronal perikarya as well as biochemically estimated GDH activity were found to be rather inhibited by such Na+ concentrations. The GDH catalyzed sodium dependent increase in formazan production is discussed to be a consequence of the sodium dependence of glutamate uptake in glutamatergic brain structures supplying the enzyme with substrate.

Animals↗
PubMed2004

Heterozygous PAX6 mutation, adult brain structure and fronto-striato-thalamic function in a human family.

Recent progress in developmental neurobiology and neuroimaging can be drawn together to provide new insight into the links between genetically specified processes of embryonic brain development and adult human brain structure and function. We used magnetic resonance imaging (MRI) to show that individuals with aniridia and deficits in executive and social cognition, due to heterozygous mutation of the neurodevelopmental control gene PAX6, have structural abnormalities of grey matter in anterior cingulate cortex, cerebellum and medial temporal lobe, as well as white matter deficits in corpus callosum. Functional MRI demonstrated reduced activation of fronto-striato-thalamic systems during performance of overt verbal fluency and nonsense sentence completion; the most consistent abnormality of verbal executive activation was located in the thalamus. These results provide the first evidence for brain functional differences in humans with PAX6 mutation that are compatible both with anatomical abnormalities in the same subjects and, more circumstantially, with the known roles of murine Pax6 in regional differentiation, axonal guidance and other aspects of early forebrain development. Highly conserved homeobox genes may be critical for normal ontogenesis of large-scale neurocognitive networks supporting phylogenetically advanced mental functions.

Adolescent↗
PubMedDate not supplied

[The effect of L-DOPA on the accumulation of lipid peroxidation products in separate brain structures during irradiation].

A study was made of the effect of L-DOPA on the dynamics of changes in lipid peroxidation products (LPP) and the content of various types of SH groups in certain brain structures (oblongata, cerebellum, visual and sensorimotor cortex) and their synaptosomal fractions upon irradiation. The preadministration of L-DOPA to irradiated rats inhibited LPP accumulation, prevented the decrease in the content of various types of thiols and thus exerted an antioxidant effect.

Animals↗
PubMed2002

Brain structures mediating the suckling stimulus-induced release of prolactin.

Suckling-induced prolactin release is a widely studied neuroendocrine reflex, comprising a neural afferent and a humoral efferent component. The information on the brain structures involved in this reflex is fairly limited. The present studies focused on this question. The following hypothalamic interventions were made in lactating rats and the dams were tested for the suckling-induced prolactin response: (i) unilateral or (ii) bilateral frontal cuts at the level of the anterior and posterior hypothalamus; (iii) administration of 5,7-dihydroxytryptamine or (iv) 6-hydroxydopamine into the hypothalamic paraventricular nucleus (PVN) to destroy serotonergic and catecholaminergic innervation of the cell group, respectively; (v) lesion of the medial subdivision of the PVN; and (vi) horizontal knife cuts below the PVN. Bilateral posterior and bilateral or unilateral anterior frontal cuts caused blockade of the suckling-induced release of prolactin. Likewise, most dams receiving 5,7-dihydroxytryptamine in the PVN did not respond to the suckling stimulus. Immunocytochemistry revealed that, in those rats which did not show a rise in plasma prolactin, there were almost no serotonergic fibres and terminals in the PVN, while in dams which exhibited a response, numerous serotonergic elements were evident. 6-Hydroxydopamine treatment did not cause significant alteration in the prolactin response. Lesion of the medial, largely parvocellular subdivision of the PVN, or horizontal knife cuts below this cell group, blocked the hormone response. The findings demonstrate for the first time that: (i) interruption of the connections between the brain stem and the hypothalamus interferes with the prolactin response to the suckling stimulus; (ii) serotonergic fibres terminating in the hypothalamic PVN are involved in the mediation of the suckling stimulus; and (iii) within the PVN, neurones in the medial, largely parvocellular subdivision of the cell group take part in the transfer of the neural signal, eventually inducing prolactin release.

5,7-Dihydroxytryptamine↗
PubMedDate not supplied

[Principle of reorganizing the functional interrelations of brain structures in action on the dopamine system of dogs].

In dogs, the influence of chronic administration of the agonist (L-DOPA) and antagonist (haloperidol) of central dopamine processes on functional interrelations of the brain structures was studied by dynamics of evoked potentials. Cortical-subcortical relations during formation of a motor habit are described in intact animals: basic functional regimes of central integration are singled out--sensory and motor one. Change of their equilibrium is the general principle of systemic reconstructions elicited by differently directed interferences in dopamine processes. Against the background of chronic administration of haloperidol, a sensory-motor imbalance is formed due to uniform functioning of the basal ganglia as analyzer of the signal stimulus; simultaneously the utilization of afferentation elicited by the movement is limited. A variant is revealed of intercentral relations corresponding to bradykinesia development. Under chronic administration of L-DOPA, interrelations of sensory and motor regimes become competitive; basal ganglia are provided with nontypical kinds of afferentations. Intercentral relations variant is examined corresponding to development of psycho-motor excitation. The results are discussed in connection with pathogenic and compensatory mechanisms of some symptoms of parkinsonism and schizophrenia.

Animals↗
PubMedDate not supplied

In vivo magnetic resonance microscopy of brain structure in unanesthetized flies.

We present near-cellular-resolution magnetic resonance (MR) images of an unanesthetized animal, the blowfly Sarcophaga bullata. Immobilized flies were inserted into a home-built gradient probe in a 14.1-T magnet, and images of voxel size (20-40 microm)(3)--comparable to the diameter of many neuronal cell bodies in the fly's brain--were obtained in several hours. Use of applied field gradients on the order of 60 G/cm allowed minimally distorted images to be produced, despite significant susceptibility differences across the specimen. The images we obtained have exceptional contrast-to-noise levels; comparison with histology-based anatomical information shows that the MR microscopy faithfully represents patterns of nervous tissue and allows distinct brain regions to be clearly identified. Even at the highest resolutions we explored, morphological detail was pronounced in the apparent absence of instabilities or movement-related artifacts frequently observed during imaging of live animal specimens. This work demonstrates that the challenges of noninvasive in vivo MR microscopy can be overcome in a system amenable to studies of brain structure and physiology.

Animals↗
PubMed1982

[Intracentral relationships of brain structures participating in blood circulation regulation].

Hemodynamic responses to stimulation of different hypothalamic sites, to simultaneous stimulation of the sinus nerve and a hypothalamic site as well as monosynaptic hypothalamic projections to brain stem structures and spinal cord as studied in anesthetized vagotomized cats revealed that hypothalamic influences to efferent link of cardiovascular control involved different efferent projections with activation of various groups of brain structures. A scheme showing intracentral monosynaptic projections participating in cardiovascular control was drawn.

Animals↗
PubMed1986

Identification of seizure-mediating brain structures with the deoxyglucose method: studies of human epilepsy with positron emission tomography, and animal seizure models with contact autoradiography.

This chapter describes tomographic and autoradiographic studies of human and animal seizure syndromes employing Sokoloff's deoxyglucose method. The method's rationale rests on two principal facts: that adult brains normally utilize glucose almost exclusively as their exogenous energy source, and that deoxyglucose, a glucose analog, accumulates in brain cells in proportion to their activity level. Thus, computed tomography or contact autoradiography allows visualization and indirect measurement of changes in the activity of different brain structures under specified conditions, such as between, during, or immediately following seizures. In humans, partial seizures have been the most extensively studied, with 18F-fluorodeoxyglucose and positron emission tomography. Interictally, the brains of patients with partial seizures are characterized by hypometabolism that is particularly severe in the vicinity of seizure foci. In many cases, these focal hypometabolic zones become hypermetabolic ictally. Other brain areas may also become hypermetabolic ictally, or they may instead become hypometabolic. Often the physical extent of interictal hypometabolic zones is substantially greater than the extent of overt pathology. This indicates that hypometabolism can result from subtle, presently undescribed, structural or functional derangements, as well as from frank neuronal loss. A variety of animal seizure "models" have also been studied, with 14C-2-deoxyglucose and contact autoradiography. Each model has produced a unique deoxyglucose and contact autoradiography. Each model has produced a unique deoxyglucose utilization pattern, but thus far none that closely resembles any of the human seizure patterns. This probably reflects true differences between the mechanisms mediating different types of animal seizures and those mediating human seizures. Although in widespread use for only a few years, the Sokoloff method has already demonstrated its ability to distinguish among a variety of seizure types in both humans and animals, and to correctly identify those structures most involved in focal seizures. Thus, the method can be of great aid in narrowing the search for seizure-mediating mechanisms.

Animals↗
PubMed1988

Allometric comparison of brain weight and brain structure volumes in different breeds of the domestic pigeon, Columba livia f.d. (fantails, homing pigeons, strassers).

In three breeds of domestic pigeons (fantails, homing pigeons, and strassers) the volumes of fresh, i.e. unfixed tissue of 14 brain structures were determined (telencephalon, diencephalon, nervus opticus, tectum, cerebellum, tegmentum and hyperstriatum accessorium, hyperstriatum ventrale, neostriatum, paleostriatum, hippocampus, septum, regio praepiriformis, bulbus olfactorius). Allometric comparisons that take into account differences in body weight and size were made among these three breeds. The tectum, hippocampus, paleostriatum and especially the neostriatum and olfactory bulb are remarkably larger in homing pigeons. These data are discussed in a functional context, in which the homing ability of homing pigeons is considered.

Animals↗
PubMed2005

Comparative analysis of MR sequences to detect structural brain lesions in tuberous sclerosis.

BACKGROUND: Tuberous sclerosis (TS) is a neurocutaneous genetically inherited disease with variable penetrance characterized by dysplasias and hamartomas affecting multiple organs. MR is the imaging method of choice to demonstrate structural brain lesions in TS. OBJECTIVE: To compare MR sequences and determine which is most useful for the demonstration of each type of brain lesion in TS patients. MATERIALS AND METHODS: We reviewed MR scans of 18 TS patients for the presence of cortical tubers, white matter lesions (radial bands), subependymal nodules, and subependymal giant cell astrocytoma (SGCA) on the following sequences: (1) T1-weighted spin-echo (T1 SE) images before and after gadolinium (Gd) injection; (2) nonenhanced T1 SE sequence with an additional magnetization transfer contrast medium pulse on resonance (T1 SE/MTC); and (3) fluid-attenuated inversion recovery (FLAIR) sequence. RESULTS: Cortical tubers were found in significantly (P<0.05) larger numbers and more conspicuously in FLAIR and T1 SE/MTC sequences. The T1 SE/MTC sequence was far superior to other methods in detecting white matter lesions (P<0.01). There was no significant difference between the T1 SE/MTC and T1 SE (before and after Gd injection) sequences in the detection of subependymal nodules; FLAIR sequence showed less sensitivity than the others in identifying the nodules. T1 SE sequences after Gd injection demonstrated better the limits of the SGCA. CONCLUSION: We demonstrated the importance of appropriate MRI sequences for diagnosis of the most frequent brain lesions in TS. Our study reinforces the fact that each sequence has a particular application according to the type of TS lesion. Gd injection might be useful in detecting SGCA; however, the parameters of size and location are also important for a presumptive diagnosis of these tumors.

Adolescent↗
PubMed1987

Microinjection of oxytocin into limbic-mesolimbic brain structures disrupts heroin self-administration behavior: a receptor-mediated event?

The systemic injection of oxytocin (OXT) decreases the self-administration of heroin in heroin-tolerant rats. Since OXT-ergic binding sites are present in limbic and mesolimbic brain regions, the effects of intracerebral microinjections of OXT were investigated. In heroin-tolerant rats, the microinjection of OXT (2 ng) into the anterodorsal part of the nucleus accumbens or into the ventral hippocampus disrupted the self-administration of heroin. The effect of intrahippocampal microinjections lasted longer than that of intraaccumbens injections. The administration of N alpha-acetyl-(2-0-methyltyrosine)-oxytocin (ACME-OXT), an inhibitor of oxytocin receptors, prevented the disruptive effect of intrahippocampal OXT injections on heroin self-administration. It is concluded that limbic-mesolimbic brain structures have an essential role in the expression of the disruptive action of OXT on heroin self-administration. It appears that OXT-ergic binding sites mediate the effects of OXT.

Animals↗
PubMed2004

The relationship between brain structure and neurocognition in schizophrenia: a selective review.

Both Kraepelin [1919. Dementia Praecox and Paraphrenia, Livingston, Edinburgh.] and Bleuler [1911. Dementia Praecox or the Group of Schizophrenias. Reprinted 1950 (trans. and ed. J. Zinkin). New York: International Univ. Press.] proposed that cognitive disturbances in schizophrenia are manifestations of brain abnormality. With the advent of magnetic resonance imaging (MRI) methodology, a number of studies have attempted to determine the relationship between brain structure and neurocognition in schizophrenia. We performed a review (1991-to date) of such studies with the aim of identifying the most consistent and compelling findings. The review revealed that whole brain volume tends to correlate with the measures of general intelligence as well as with a range of specific cognitive functions in normal controls and female schizophrenia patients, but this relationship is disrupted in male patients. The enlargement of the third ventricle, relative to the whole brain volume, is associated with deficient abstraction/flexibility, language, and attention/concentration in patients, whereas disproportionally larger lateral ventricles are associated with poorer psychomotor speed and attention/concentration in women, but not in men, with schizophrenia. Archicortical, but not paleocortical, prefrontal cortex tends to associate with the measures of executive function in both sexes regardless of diagnosis. Temporal lobe, hippocampus and parahippocampal gyrus correlate with cognitive abilities such as performance speed and accuracy, memory and executive function, verbal endowment and abstraction/categorization, respectively. Some of these medial temporal lobe/neurocognition relationships appear to be specific to schizophrenia (i.e. not seen in controls). Striatal size is positively associated with goal-directed behavior, but not perseveration, in schizophrenia. Larger cerebellum is associated with higher IQ in normal controls and affected women, but this association is disrupted in affected men. Increased white matter of the vermis is associated with poorer language and immediate verbal memory in schizophrenia. Finally, the methodological limitations of the reviewed studies are discussed and suggestions for future research are offered.

Attention↗
PubMed1998

Allometric comparison of the brain and brain structures in the white crested polish chicken with uncrested domestic chicken breeds.

The feather crest on the head of the White Crested Polish Chicken covers a bony protuberance, a skull modification typical of crested chickens. The telencephalon is displaced into this protuberance, giving the brain the shape of an hour-glass. Allometric comparison (i.e., consideration of the influence of body weight on brain size) shows that the brain is relatively larger in crested chickens. This enlargement is partly due to enlarged ventricles, which are observed in some individuals. Among the brain structures measured, the tegmentum, cerebellum, tectum, paleostriatum, hippocampus, septum and olfactory bulb are not significantly larger in White Crested Polish chickens in comparison to those structures in seven uncrested chicken breeds; the optic tract, diencephalon, telencephalon, accessory hyperstriatum, dorsal and ventral hyperstriatum, and neostriatum, however, are significantly enlarged in this breed.

Animals↗
PubMed1983

[Respiratory system activity in laser irradiation of brain structures].

It has been shown that the low-level laser radiation with the wave-length in the red part of spectrum changes greatly the activity of the respiratory center under the direct influence on the rats' brain structure. The influence of light may have activating or inhibitory character; sometimes symmetry in the respiratory center activity is disturbed. The difference of the effects under the radiation of the sensomotor area of the cerebral cortex hemispheres and the area of the bulbar respiratory center has been found out. It is supposed that one of the reasons of the functional state of the respiratory center variations is the metabolism change in its structures.

Animals↗
PubMed1996

Brain structure and task-specific increase in expression of the gene encoding syntaxin 1B during learning in the rat: a potential molecular marker for learning-induced synaptic plasticity in neural networks.

The mRNAs encoding the synaptic vesicle proteins syntaxin 1B and synapsin I were measured using in situ hybridization in several brain regions--the dentate gyrus, CA3 and CA1 of the hippocampus, the parietal, the motor and prefrontal cortices and the core and shell of the accumbens--of rats that were learning a spatial reference or working memory task on a radial arm maze. The mRNA encoding syntaxin 1B was significantly increased in all hippocampal regions in rats learning the working memory task, whereas it was increased in the prelimbic area of the prefrontal cortex and the shell of the accumbens in rats learning the spatial reference memory task. No change in mRNA encoding syntaxin 1B was observed in the motor and parietal and cortices or the core of the accumbens, and the mRNA encoding synapsin I was not significantly different from that of naive caged controls or rats running the maze for continuous reinforcement in any of the brain structures examined. These results demonstrate that the gene encoding a key member of synaptic vesicle function is up-regulated in a task- and brain-specific manner during learning. They are discussed in terms of the potential role this protein may play in trans-synaptic propagation of plasticity within specific neural networks as a function of the information required in the laying down of different types of memory.

Animals↗
PubMed1979

The emotiogenic brain structures in conditioning mechanisms: conditioned evoked potentials and motor responses.

The emotiogenic rnorphofunctional control system consists of the amygdaloid complex (AM), the zona incerta, the peri- and paraventricular nuclei of the hypothalamus and the midbrain central gray matter (CG). The neuronal relationships between the structures of this system were established. Lesions of these structures prevented one-trial learning, whereas electrical stimulation of the AM or the CG permitted retrieval of a trace which was lower than threshold. AM stimulation accelerated learning by 5-10 times. The possible mechanisms of the emotiogenic control system of memory' are discussed. The contribution of the identified structures of the emotiogenic control system of memory was quantitatively estimated, by employing a matrix of the interaction of these structures during the performance of conditioned neurographic responses of the radial nerve. The approach established the role of the emotiogenic control system in the spatial-temporal organization of brain structures needed for the retrieval of conditioned motor responses. Weakly trained cats, in which the AM-CG had been stimulated, did not differ from well trained ones in the patterns and correlation matrices of the conditioned evoked potentials. AM-CG activation may accelerate learning by reproducing such spatial-temporal relationships that are characteristic of well trained animals.

Amygdala↗
PubMed1990

A multiwire microelectrode for single unit recording in deep brain structures.

A method is described by which a single shaft multiwire microelectrode can be fabricated efficiently. The resulting electrode can be attached to a commercial microdrive and used for single neuronal unit recording from one or more tracks in deep brain structures of anesthetized or awake animals. The electrode consists of a 30 gauge stainless steel cannula through which multiple strands of 13 micron insulated tungsten microwires are threaded. At the electrode tip the wires protrude 3-4 mm from the cannula and are cut individually at suitable offsets. The tip is stabilized and fixed to the cannula with cyanoacrylate. At the base of the electrode the wires are threaded through flexible plastic tubing that provides strain relief and are glued to individual pins of a miniature connector that plugs into a field effect transistor (FET) voltage follower. Good single unit recordings have been obtained routinely from the basal ganglia of awake, behaving monkeys with this electrode.

Action Potentials↗