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At least 415 records · Page 23Linked to original sources
PubMed2006

Variant BDNF (Val66Met) impact on brain structure and function.

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are a unique family of polypeptide growth factors that influence differentiation and survival of neurons in the developing nervous system. In adults, BDNF is important in regulating synaptic plasticity and connectivity in the brain. Recently, a common single-nucleotide polymorphism in the human BDNF gene, resulting in avaline to methionine substitution in the prodomain (Val66Met), has been shown to lead to memory impairment and susceptibility to neuropsychiatric disorders. An understanding of how this naturally occurring polymorphism affects behavior, anatomy, and cognition in adults is an important first step in linking genetic alterations in the neurotrophin system to definable biological outcomes in humans. We review the recent literature linking this BDNF polymorphism to cognitive impairment in the context of in vitro and transgenic animal studies that have established BDNF's central role in neuronal functioning in the adult brain.

Animals↗
PubMedDate not supplied

Brain structure localization in positron emission tomography: comparison of magnetic resonance imaging and a stereotactic method.

A method commonly used for localization of brain regions on positron emission tomographic (PET) images is direct visualization and designation of structure on the image itself. This technique, however, is limited to portions of the brain having sufficient differential radionuclide uptake to permit the recognition of structure by observers familiar with brain anatomy. Two other methods commonly used instead of direct visualization are magnetic resonance imaging (MRI) and stereotactic methods of localization. This report compares the accuracy of a MRI method versus a stereotactic method of brain structure localization of PET. The three localization methods were analyzed for sixteen different brain regions in 5 different subjects by two independent observers. The results were converted to PET pixel size (1 pixel = .127 cm) for comparison. MRI localization differed from direct visualization by a mean and standard deviation of approximately 2 +/- 1 pixels in both the X and Y dimensions. Stereotactic localization differed from direct visualization by approximately 2 +/- 1 pixels in the X dimension and by approximately 6 +/- 2 pixels in the Y dimension. This larger variation seen with the stereotactic method may be attributed to the questionable assumption of linearity of structure location with respect to size of the inner table of the calvarium.

Adult↗
PubMed2000

Effects of early adverse experiences on brain structure and function: clinical implications.

Child abuse is associated with markedly elevated rates of major depression and other psychiatric disorders in adulthood. This article reviews preclinical studies examining the effects of early stress, factors that modify the impact of these experiences, and neurobiological changes associated with major depression. Preclinical studies demonstrate that early stress can alter the development of the hypothalamic-pituitary-adrenal axis, hypothalamic and extrahypothalamic corticotropin releasing hormone, monoaminergic, and gamma-aminobutyric acid/benzodiazepine systems. Stress has also been shown to promote structural and functional alterations in brain regions similar to those seen in adults with depression. Emerging data suggest, however, that the long-term effects of early stress can be moderated by genetic factors and the quality of the subsequent caregiving environment. These effects also can be prevented or reversed with various pharmacologic interventions. Preclinical studies of early stress can provide valuable insights in understanding the pathophysiology and treatment of major depression. They also can provide an important tool to use to investigate interactions between genes and environments in determining an individual's sensitivity to stress. More research is needed to understand how inherent factors interact with experiences of abuse and other psychosocial factors to confer vulnerability to develop depression.

Age Factors↗
PubMed2001

Effects of early stress on brain structure and function: implications for understanding the relationship between child maltreatment and depression.

Child abuse is associated with markedly elevated rates of major depression (MDD) in child, adolescentt, and adult cohorts. This article reviews preclinical (e.g., animal) studies of the effects of early stress and studies of the neurobiological correlates of MDD in adults and children, and it highlights differences in the neurobiological correlates of MDD and stress at various developmental stages. The preclinical studies demonstrate that stress early in life can alter the development multiple neurotransmitter systems and promote structural and functional alterations in brain regions similar to those seen in adults with depression. Preclinical and clinical studies suggest, however, that long-term neurobiological changes associated with early stress can be modified by familial/genetic factors, the quality of the subsequent caregiving environment, and pharmacological interventions. Little is known about how developmental factors interact with experiences of early stress and these other modifying factors. Moreover, in cases of child maltreatment, the effects of early abuse are often exacerbated by failures in the child protection system and repeat out-of-home placements. Given the number of factors that impact on the long-term outcome of maltreated children, multidisciplinary research efforts are recommended to address this problem-with foci that span from neurobiology to social policy.

Adrenocorticotropic Hormone↗
PubMed2004

Neuroanatomy of "hearing voices": a frontotemporal brain structural abnormality associated with auditory hallucinations in schizophrenia.

Auditory hallucinations are a frequent symptom in schizophrenia. While functional imaging studies have suggested the association of certain patterns of brain activity with sub-syndromes or single symptoms (e.g. positive symptoms such as hallucinations), there has been only limited evidence from structural imaging or post-mortem studies. In this study, we investigated the relation of local brain structural deficits to severity of auditory hallucinations, particularly in perisylvian areas previously reported to be involved in auditory hallucinations. In order to overcome certain limitations of conventional volumetric methods, we used deformation-based morphometry (DBM), a novel automated whole-brain morphometric technique, to assess local gray and white matter deficits in structural magnetic resonance images of 85 schizophrenia patients. We found severity of auditory hallucinations to be significantly correlated (P < 0.001) with volume loss in the left transverse temporal gyrus of Heschl (primary auditory cortex) and left (inferior) supramarginal gyrus, as well as middle/inferior right prefrontal gyri. This demonstrates a pattern of distributed structural abnormalities specific for auditory hallucinations and suggests hallucination-specific alterations in areas of a frontotemporal network for processing auditory information and language.

Adult↗
PubMed1986

[Content of neuron-specific and non-neuron-specific enolase isoenzymes in human brain structures].

The distribution of neuron-specific (NSE) and non-neuronal (NNE) isoforms of glycolytic enzyme enolase (EC 4.2.I.II.) in the human brain was studied using immunoenzyme assay. The maximum NSE concentration was measured in the frontal and occipital brain cortex, hippocampus, limbic cortex and hypothalamus (12-14 micrograms/mg of water-soluble protein), the minimum level was observed in the brain stem structures (3-6 micrograms/mg). The maximum NNE content was determined in thalamus (34 micrograms/mg). The data can prove useful for the study of enolase isoform distribution in the brain of neurological and psychiatric patients.

Brain↗
PubMed2005

Interleukine-1beta and interleukine-6 levels in striatum and other brain structures after MPTP treatment: influence of behavioral lateralization.

MPTP (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) induces diminution of the dopamine in nigrostriatal pathway and cognitive deficits in mice. MPTP treatment also increases pro-inflammatory cytokine production in substantia nigra and striatum. Since, pro-inflammatory cytokines influence striatal dopamine content and provoke cognitive impairments, the cognitive defects induced by MPTP may be partly due to brain cytokine induction in other structures than nigrostriatal pathway. Furthermore, behavioral lateralization, as assessed by paw preference, influences cytokine production at the periphery and in the central nervous system. Behavioral lateralization may thus influence brain cytokine levels after MPTP. In order to address these issues, mice selected for paw preference were injected with 25 mg/kg MPTP i.p. for five consecutive days after which striatal dopamine and DOPAC contents were measured by HPLC and IL-1beta and IL-6 quantified by ELISA in the striatum, cerebral cortex, hippocampus and hypothalamus. The results showed that MPTP treatment induced dramatic loss of DA in striatum, simultaneously, IL-6 levels decreased in the striatum and increased in hippocampus and hypothalamus, while IL-1beta levels decreased in the striatum, cerebral cortex and hippocampus. Interestingly, striatal dopamine turnover under basal conditions as well as striatal IL-1beta and IL-6 levels under basal conditions and after MPTP depended on behavioral lateralization. Left pawed mice showed a higher decrease in dopamine turnover and lower cytokine levels as compared to right pawed animals. Behavioral lateralization also influenced IL-6 hippocampal levels under basal conditions and IL-1beta cortical levels after MPTP. From these results, it can be concluded that MPTP-induced cognitive defects are accompanied by an alteration of pro-inflammatory cytokine levels in brain structures other than those involved in the nigrostriatal pathway. In addition, MPTP-induced dopamine decrease is influenced by behavioral lateralization, possibly through an effect on brain cytokine levels.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1981

[Distribution of horseradish peroxidase-labeled neurons, sources of descending fiber systems, in subcortical brain structures and the hypothalamus of cats].

Location of neurons which initiate different descending fibre systems from amygdaloid nuclei, basal ganglia and hypothalamus to brain stem was studied using the method of horse-radish peroxidase retrograde axonal transport. It was shown that neurons from magnocellular part of the basal amygdaloid nucleus and medial part of central amygdaloid nucleus send their axons to the dorsal hypothalamus, substantia nigra, lateral area of the mesencephalic central grey and midbrain reticular formation at the level of inferior olives. The central amygdaloid nucleus is the main source of projections to the hypothalamus and brain stem structures. It also sends projections to the nucleus of solitary tract and to the dorsal motor nucleus of the vagus. Uncrossed descending fibre systems from the basal ganglia terminate at the pons level, while the uncrossed and crossed fibre systems from dorsolateral and ventromedial areas of hypothalamus descend into the spinal cord. A possible role of the amygdaloid nuclei, basal ganglia, hypothalamus and their different pathways in regulation of somatic and autonomic functions and complex behavioural and emotional responses is discussed.

Amygdala↗
PubMed1987

Blood flow in brain structures during increased ICP.

The effect of a supratentorial expanding mass lesion and of uniform increase of ICP on regional cerebral blood flow was examined in 31 cats. The blood flow was measured using the radioactive microsphere technique and continuous ICP increase was produced by inflating an extradural balloon or by infusion of mock CSF into subarachnoid lumbar space. Four additional animals in whom no ICP rise was produced were used as controls; several blood flow measurements were performed at different ICP levels and after sudden ICP release. The analysis of the data obtained revealed that intracranial hypertension caused inhomogenous pattern of blood flow change with compartmentalization of flow between supra- and infratentorial structures connected with cisternal herniation. The flow decrease may correspond to the craniocaudal pressure gradients in the brain stem. Irrespective of the method used to produce intracranial hypertension the blood flow in the lower brain stem was less susceptible to diminished perfusion pressure. Sparing of cerebral blood flow in the lower brain stem during progressive brain compression can be explained by compartmentalization. The ranking of regions at cerebral perfusion pressure below 60 mm Hg was similar for the lower brain stem regions independently of the method which was used to increase the ICP. This suggests that when CBF becomes reduced due to increase of ICP the perfusion favours the areas where neurons related to control of circulation are located. Diffuse increase of ICP produced no interhemispheric differences in the blood flow. These differences were detected when balloon compression was used. Asymmetry of perfusion in the brain stem structures was not observed. During continuously increasing ICP an increase of blood pressure taking place before pupillary dilatation occurred was not caused by medullary ischaemia. If the pressure continued to increase the vasopressor response occurring after pupillary dilatation took place did not improve the cerebral blood flow. Increase of cerebral perfusion followed a sudden release of ICP. In an experimental animal subjected to unilateral compressive lesion producing tentorial herniation, hyperperfusion involved especially the thalamus and the midbrain with relative flow decrease in the lower brain stem.

Animals↗
PubMedDate not supplied

Effect of kindled seizures on rat behavior in water Morris maze test and amino acid concentrations in brain structures.

The effects of kindled seizures elicited by repeated pentetetrazole (PTZ) injections, on learning and memory in the Morris water maze test and on concentration of brain amino acids, were examined in rats. It was found that kindled seizures (a model of temporal lobe epilepsy) produced a profound decrease in learning and memory accompanied by a selective and long-lasting decrease in hippocampal and striatal concentration of glutamate, glycine and alanine in the striatum (ex vivo measurement). The concentrations of histamine, serine and gamma-aminobutyric acid (GABA) were not selectively affected by kindling. Alower concentration of glutamate and N-methyl-D-aspartate (NMDA) receptor co-agonists in the striatum (glycine and alanine) indicates the general malfunction of the brain glutamatergic system. It is suggested that a selective decrease in hippocampal glutamate concentration may account for deterioration in learning and memory processes in kindled rats, considering the important role of this neurotransmitter in the cognitive processes (e.g. in the long-term potentiation), and the key contribution of the hippocampus to the spatial memory. The intrinsic mechanisms of the reported behavioral effects may involve neuronal damage in the brain limbic structures, secondary to seizure-induced ischemia and hypoxia.

Amino Acids↗
PubMed2002

Fetal hypoxia and structural brain abnormalities in schizophrenic patients, their siblings, and controls.

BACKGROUND: Cortical gray matter reductions and cerebrospinal fluid (CSF) increases are robust correlates of schizophrenia, but their relationships to obstetric and other etiologic risk factors remain to be established. METHODS: Structured diagnostic interviews, obstetric hospital records, and magnetic resonance imaging scans of the brain were obtained for 64 schizophrenic or schizoaffective patients (representative of all such probands in a Helsinki, Finland, birth cohort), along with 51 of their nonpsychotic full siblings and 54 demographically similar controls without family histories of psychosis. RESULTS: Fetal hypoxia predicted reduced gray matter and increased CSF bilaterally throughout the cortex in patients (gray matter effect sizes, -0.31 to -0.56; CSF effect sizes, 0.25 to 0.47) and siblings (gray matter effect sizes, 0.33 to 0.47; CSF effect sizes, 0.17 to 0.33), most strongly in the temporal lobe. Effect sizes were 2 to 3 times greater among cases born small for their gestational age. Hypoxia also correlated significantly with ventricular enlargement, but only among patients (effect size, 0.31). In contrast, fetal hypoxia was not related to white matter among patients and siblings, nor to any tissue type in any region among controls. The associations were independent of family membership, overall brain volume, age, sex, substance abuse, and prenatal infection. CONCLUSIONS: Fetal hypoxia is associated with greater structural brain abnormalities among schizophrenic patients and their nonschizophrenic siblings than among controls at low genetic risk for schizophrenia. This pattern of results points to a gene-environment interaction account of the disorder's neurodevelopmental pathogenesis.

Adult↗
PubMed1980

The interaction between sensory and nonsensory factors in the determination of brain structure and chemistry: a review.

Contrary to previous thinking, the brain is now recognized as a plastic organ whose structure and function adapt to the functional demands of the sensory environment. This paper examines the interaction between sensory and nonsensory brain-modifying factors in determining the psychobiological outcome in animals reared under conditions of environmental complexity and deprivation. Stimulant drugs appear to enhance complexity effects and depressants to reduce them. Hormones affected by hypophysectomy or castration do not appear to interfere with sensory effects, though a progestogen norethynodrel does appear to interact with them. For genetic effects, strain, species and sex may interact, with male hybrids being perhaps most susceptible to environmental effects. The picture which is emerging is of the brain as inextricably linked to its environment and suggests that a full study demands a recognition of the ecological context. This picture of multiway inter-dependencetrain species and sex may interact, with male hybrids being perhaps most susceptible to environmental effects. The picture which is emerging is of the brain as inextricably linked to its environment and suggests that a full study demands a recognition of the ecological context. This picture of multiway inter-dependencetrain species and sex may interact, with male hybrids being perhaps most susceptible to environmental effects. The picture which is emerging is of the brain as inextricably linked to its environment and suggests that a full study demands a recognition of the ecological context. This picture of multiway inter-dependence and interdetermination or "omnideterminism" is similar to the holistic orgnaismic picture of the universe of the millenia-old yogi-consciousness disciplines and of modern physics.

Animals↗
PubMed1993

Hydroxyindole-O-methyltransferase activity in ocular and brain structures of rabbit and hen.

Relative activities of hydroxyindole-O-methyltransferase (HIOMT) of some brain and ocular structures of the rabbit and hen were analyzed using different 5-hydroxyindoles, i.e., N-acetylserotonin (NAS), 5-hydroxytryptophol (HTOL), 5-hydroxytryptophan (HTP), 5-hydroxytryptamine (HT), and 5-hydroxy-3-indoleacetic acid (HIAA), as enzyme substrates. Pineal glands of both species, as well as hen retina, are capable of producing, to varying degrees, melatonin, 5-methoxytryptophol, and 5-methoxytryptamine. Hen choroid and iris-ciliary body O-methylated NAS and HTOL, whereas rabbit choroid and, to a much lesser extent, hypothalamus and cerebral cortex all O-methylated only NAS. No measurable HIOMT activity was found in hen brain. NAS was a preferred substrate for HIOMT in the hen tissues, whereas in the rabbit pineal gland NAS and HTOL were equally good substrates for HIOMT. Other tested 5-hydroxyindoles, i.e., HTP, HT, and HIAA, were poor methyl acceptors. Of the tissues examined, the highest HIOMT activity was found in the hen pineal gland, followed by the rabbit pineal gland and hen retina. No significant differences between day and nighttime enzyme activities were observed in the pineal gland and retina of either species. The data suggest that in vertebrates some nervous and ocular tissues possess the potential to produce 5-methoxyindole compounds; however, the HIOMT-catalyzed process shows remarkable substrate-, tissue- and species-dependent variations.

Acetylserotonin O-Methyltransferase↗
PubMed1997

Structural brain abnormalities in male schizophrenics reflect fronto-temporal dissociation.

BACKGROUND: Many studies have separately reported abnormalities of frontal and temporal lobe structures in schizophrenia, but little is known of structural fronto-temporal associations in this condition. We investigated whether male patients with chronic schizophrenia would show abnormal patterns of correlation between regional brain volumes. METHODS: Structural magnetic resonance images of the brain in 42 patients were compared with 43 matched unaffected controls. We explored the pattern of association between regional brain volumes by correlational analyses, and non-parametrically tested for significance of between-group differences by randomization. RESULTS: The schizophrenics demonstrated significant volume deficits in several brain regions (left temporal lobe and hippocampus, right dorsolateral prefrontal cortex), and significant volume increases in the ventricular system (third ventricle and left temporal horn of the lateral ventricle). Controls demonstrated large positive correlations (r > 0.4) between prefrontal and temporal lobe regions. By contrast, inter-regional correlations significantly reduced in schizophrenics included those between prefrontal, anterior cingulate and temporal regions, and between posterior cingulate and hippocampus (P < 0.05). The most salient abnormality in patients was a dissociation between prefrontal and superior temporal gyrus volumes (P < 0.01). CONCLUSIONS: These results support the existence of a relative 'fronto-temporal dissociation' in schizophrenia which we suggest may be due to lack of mutually trophic influences during frontal and temporal lobe development.

Chronic Disease↗
PubMed2005

Brain structural mapping using a novel hybrid implicit/explicit framework based on the level-set method.

This paper presents a novel approach to feature-based brain image warping, by using a hybrid implicit/explicit framework, which unifies many prior approaches in a common framework. In the first step, we develop links between image warping and the level-set method, and we formulate the fundamental mathematics required for this hybrid implicit/explicit approach. In the second step, we incorporate the large-deformation models into these formulations, leading to a complete and elegant treatment of anatomical structure matching. In this latest approach, exact matching of anatomy is achieved by comparing the target to the warped source structure under the forward mapping and the source to the warped target structure under the backward mapping. Because anatomy is represented nonparametrically, a path is constructed linking the source to the target structure without prior knowledge of their point correspondence. The final point correspondence is constructed based on the linking path with the minimal energy. Intensity-similarity measures can be naturally incorporated in the same framework as landmark constraints by combining them in the gradient descent body forces. We illustrate the approach with two applications: (1) tensor-based morphometry of the corpus callosum in autistic children; and (2) matching cortical surfaces to measure the profile of cortical anatomic variation. In summary, the new mathematical techniques introduced here contribute fundamentally to the mapping of brain structure and its variation and provide a framework that unites feature and intensity-based image registration techniques.

Algorithms↗
PubMed1991

[Autoradiography of protein synthesis as a method of assessment of morphofunctional changes in brain structures].

A combination of two groups of autoradiography technique (for a hole brain and individual cells) was applied with using 3H-leucine to evaluate the changes of brain functional activity on the level as anatomical structures and as different type neurons. It was found that Wistar rats with lowered motor activity induced by 3-4 weeks treatment with L-DOPA 100 mg/kg displayed the motor nuclei of the brain stem the cerebellum as highly labelled structures and the motor cortex and n. caudatus as feebly ones in comparison with control. However, a quantitative assessment of silver grains over the neurons of layers III and V of motor cortex and n. caudatus showed not only a significant increase of labelling, especially in neurons of layer V on 174%, in comparison with control but revealed unequal labelling of different type neurons. It was concluded that the applied two groups of autoradiography technique can be a useful approach to assess the brain functional activity.

Animals↗
PubMed1981

[Role of certain brain structures in the generation and spread of alpha-like activity in dogs peculiar to the early stages of the postresuscitation period].

The role played by the amygdaloid nucleus, caudate nucleus, thalamus and brain cortex in propagation throughout the brain of generalized limbic alpha-like activity recorded on the EEG in the early postresuscitation period was studied in experiments on dogs resuscitated after a 13-15-minute circulatory arrest. Destruction or pharmacological inhibition of both amygdaloid nuclei resulted in disappearance of alpha-like activity from all the test structures. Coherent analysis showed that the caudate nucleus and thalamus, in particular, take an active part in propagation of alpha-like waves of biopotentials from the amygdaloid nucleus to other brain structures.

Amygdala↗