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PubMed1996

Juvenile hormone, behavioral maturation, and brain structure in the honey bee.

Juvenile hormone regulates metamorphosis in insects, and its effects on the nervous system during the larval-pupal transition have been studied primarily in the hawk moth, Manduca sexta. The effects of juvenile hormone on the nervous system of adult insects have been little studied. Elucidating the role of juvenile hormone during behavioral development in adult honey bees provides an opportunity to study hormone regulation of nervous system structure and function in an insect with a rich behavioral repertoire and social life. A worker honey bee typically lives 30-60 days. During this time, she performs a sequence of different tasks that sustain the colony. A striking behavioral transition typically occurs at about 3 weeks of age. At this time, worker bees stop performing within-hive tasks such as rearing brood and building comb and begin to forage outside the hive. This behavioral development is accompanied by a marked increase in the production of juvenile hormone. The mushroom bodies of the protocerebrum, the region of the insect brain most often associated with learning and memory, also undergo an internal reorganization during behavioral development. High titers of juvenile hormone and an increased volume of neuropil associated with the mushroom bodies are characteristic of the forager. Importantly, the time of the behavioral transition to foraging is not fixed. Individual bees can respond to changing colony or environmental conditions by accelerating or delaying the switch from within-hive tasks to foraging. For example, in the absence of older workers, some bees will undergo precocious development and may forage as early as 4 days of age. These workers also experience a precocious rise in juvenile hormone and an earlier reorganization of the mushroom bodies. Our current studies investigate the roles played by juvenile hormone and experience in shaping the mushroom bodies of the adult honey bee, and the relationship of these changes to the bee's ability to forage successfully. It is proposed that juvenile hormone may mediate neural plasticity in the brains of adult honey bees to support the demanding cognitive task of foraging.

Animals↗

PubMed1991

Influence of neurotransmitters on sexual differentiation of brain structure and function.

Newborn rats received daily subcutaneous treatment with compounds which influence serotoninergic, cholinergic, alpha-adrenergic and beta-adrenergic activity. In adulthood luteinizing hormone (LH) secretion pattern, female sexual behavior, and the volume of the sexually dimorphic nucleus of the preoptic are (SDN-POA) were determined. Postnatal administration of l-tryptophan increased the volume of the SDN-POA significantly when given alone or when given simultaneously with testosterone propionate (TP). Para-chlorophenyl-alanine (pCPA) also increased SDN-POA volume, but did not potentiate the stimulating influence of TP. Clonidine had no effect per se on SDN-POA development, but it significantly potentiated the effect of TP in females. Salbutamol increased SDN-POA volume in females and in males. Postnatal treatment of female rats with the alpha-adrenergic receptor antagonists prazosine and yohimbine or with the nicotin receptor antagonist mecamylamine had permanent potentiating effects on the pattern of LH secretion, whereas postnatal treatment with beta-adrenergic compounds reduced the LH-release response to gonadal steroids in adulthood. Postnatal treatment with clonidin or l-tryptophane inhibited differentiation of the capacity for lordosis behavior. Beta-receptor agonists postnatally had a potentiating effect on the capacity for lordosis behavior in female and male rats. Cholinergic stimulation postnatally inhibited differentiation of the capacity for lordosis behavior in female rats, but prevented the inhibitory effect of postnatal androgenization. There was no correlation between SDN-POA volume and any of the two functional parameters.

Animals↗

PubMed1994

Relationship between brain structure and function in disorders of the schizophrenic spectrum: single positron emission computerized tomography, computerized tomography and psychopathology of first episodes.

Fifty newly diagnosed, briefly treated or drug-naive patients with schizophrenia or schizophreniform disorder were examined by psychopathology scales for positive (SAPS), negative (SANS) and overall psychotic symptoms (PSE and BPRS). CT-scan and regional cerebral blood flow (rCBF) measurement by 99mTc-HMPAO SPECT during rest and mental activation by Wisconsin Card Sorting Test was performed as well. Twenty-five age-matched normal healthy volunteers served as controls. Thought disorders and fundamental symptoms correlated positively with relatively high, though subnormal prefrontal (PFC) rCBF and high rCBF in temporal cortex; positive symptoms correlated positively with high rCBF in the striatum and temporal cortex during activation. Negative symptoms correlated with high prefrontal rCBF. The patients had sulcal enlargement and smaller brain volume compared with the healthy volunteers. There were no signs of ventricular enlargement. Neither total negative symptoms, thought disorder nor fundamental symptoms correlated with any CT measurements. Total positive symptoms correlated negatively with the size of the temporal horns. The relatively high rCBF in PFC and temporal cortex of cases with pronounced positive and negative symptoms and thought disorder may imply that an aberrant cortical network has to be active to express a malattuned clinical output. The striatal hyperfunction mainly in productive cases may be a secondary phenomenon and more pronounced in cases where no signs of subcortical atrophy has (yet?) ensued.

Adolescent↗

PubMedDate not supplied

Comparison of the effects of dopamine agonists on self-stimulation of the hypothalamus with lesioning of mesolimbic brain structures in rats reared in conditions of social isolation.

Initial and phenamine-stimulated frequencies of self-stimulation of the lateral hypothalamus were not significantly different in rats reared in communities and in conditions of social isolation. Unilateral lesioning of the ventral tegmental area and the medial prefrontal cortex in early ontogenesis increased phenamine sensitivity only in isolated rats. The dopamine receptor agonist apomorphine, at a dose of 0.05 mg/kg, which affects presynaptic receptors, inhibited the self-stimulation response in intact group-reared animals and in rats reared in isolation, by 21-23%. Stimulation of the ventral tegmental area did not change, while stimulation of the medial prefrontal cortex doubled the sensitivity of rats to apomorphine in animals reared in isolation (at doses of 0.05 and 0.5 mg/kg). Conditions of partial sensory and complete species isolation resulted in the development of a state of presynaptic receptor hypersensitivity of dopamine receptors in mesocorticolimbic brain systems in rats.

Amphetamine↗

PubMed1979

[Changes in the millivolt potential of brain structures during micropolarization influencing trace phenomena].

In chronic experiments on monkeys and cats, the effects of intracerebral micropolarization modulating memory processes, on the mV potential of cerebral structures, were studied. A connection was revealed between trace fixing and processes of systemic kindling on the one hand, and the following stabilizing of mV potential, on the other hand. The data obtained suggest that the distant changes of the mV potential reflect a general "tuning" of cerebral systems, are realized by means of specialized regulatory neuronal networks and connected with shifts in metabolic processes.

Animals↗

PubMedDate not supplied

[Role of monoaminergic systems in the development of the effect of stimulation of acetylcholinergic brain structures in the cat].

The influence of systemic injection of anticholinesterase substance physostigmine on the behaviour of cats was studied under the conditions of pharmacological stimulation of monoaminergic cerebral systems. Development of the effect of the substance with an increase of its dose was accompanied by a successive alternation of three phases each representing an independent form of behaviour. Each form of behaviour originating in the process of acetylcholinergic stimulation increase was supposed to be caused by an involvement of corresponding monoaminergic system: serotonindopamine-, or noradrenergic one.

Acetylcholine↗

PubMed1990

[Changes in the level of dopamine and its metabolites in brain structures and immunocompetent organs in the formation of immune response].

By the method of liquid chromatography with electrochemical detection dopamine level increase was shown within 2 min after immunization of rats with sheep red blood cells in n. caudatus. In 20 min after the immune response the acceleration of dopamine metabolism was observed in nuclei A9, A10, A11, accumbens, in amygdala, hypothalamus and hippocampus. In immunocompetent organs dopamine level was changed in 24 h after the immunization.

Adrenal Glands↗

PubMed1977

[Selective effect of decimeter waves on central brain structures].

Sensitivity of central cerebral structures to the action of the electromagnetic fields of decimetre waves (DMW) was studied with the aid of unit activity of comissural neurons. The greatest reactivity to DMW was found in neurons of hypothalamus and hippocampus. Neurons of the midbrain RF and of the specific thalamic nuclei displayed mainly an inhibitory response. The number of neurons responding to the DMW varied depending on the energetical density.

Animals↗

PubMed1985

The involvement of brain structures in the adjuvant effect of muramyl dipeptide.

With the aid of small electrolytic lesions we have studied the possible participation of brainstem structures in the adjuvant activity of muramyl dipeptide (MDP). The results suggest the involvement of the serotonergic groups B6.7.8 and serotonergic pathways in the upper region of the reticular formation. Since lesions in the caudal parts of reticular formation in the area of aminergic groups A1.3.5.7 with the participation of corresponding pathways also influenced the adjuvant effect of MDP the possible role of noradrenaline is also implicated.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed2003

Obstetric complications correlate with neurobehavioral and brain structural alterations in young relatives at risk for schizophrenia.

As complications of pregnancy and birth may be important risk factors for the development of schizophrenia, studying the "roots" of schizophrenia in high-risk offspring may better elucidate the interface between biology, environment, and susceptibility to illness. Using magnetic resonance imaging (MRI), neurobehavioral assessments and obstetric histories, we found several significant correlations between these multiple factors, suggesting that birth complications may be a nonspecific etiopathogenic risk factor for psychopathology in young relatives at risk for schizophrenia.

Adolescent↗

PubMed2000

[Effect of the transcranial electrical stimulation of the endorphinergic brain structures on the functional activity of hepatocytes after toxic exposure].

Biochemical events of the rat hepatocytes cytolysis and deterioration of their synthetic activity and detoxification ability, as well as morphological events of lipid degeneration after acute poisoning with dichloretane and CCl4, were significantly reduced by effects of transcranial stimulation (TES). Blockade of the TES effects with naloxone revealed its endorphinergic nature. Combined effects of the TES and Essenciale preparation were lower than separate those of these agents. The TES effects were clinically corroborated in treatment of toxic hepatitis.

Animals↗

PubMed1987

Comparison of brain structure volumes in Insectivora and primates. VII. Amygdaloid components.

Volumes of the amygdaloid complex (AMY) and some subdivisions were measured in 2 species of Macroscelidea, 39 species of Insectivora, 3 species of Scandentia, 18 species of prosimians, 26 species of simians and man. Changes in the relative size from Insectivora through man (expressed by size indices) showed a definite tendency to increase in the cortico-basolateral subdivision (LAM) and more or less constant relations in the centromedial subdivision (MAM), except for the nucleus tractus olfactorii lateralis (NTO), which becomes distinctly reduced. The reduction of NTO is even stronger than that of the main olfactory bulb (BOL), which in simians and man is small but distinct, whereas NTO is hardly recognizable in most of these forms. In the LAM group the size increase of the large-celled part of the basal nucleus (MCB) is less than that of the small-celled components (including the lateral nucleus). The differences between LAM and MAM groups are discussed with regard to the predominant fiber connections, which in MAM are stronger with conservative brains parts (brainstem), and in LAM with progressive brain parts (e.g. neocortex).

Amygdala↗

PubMed1988

Brain structure and function in sexual molesters of children and adolescents.

Sixteen men incarcerated in a state psychiatric facility pursuant to sexual molestation of children and/or adolescents were evaluated by computed tomography (CT) head scans and regional cerebral blood flow (rCBF) estimation. Compared with controls, child molesters were found to have thinner and less dense skulls and lower rCBF values. Variations from control values in rCBF and characteristics of CT head scans for the sex offenders suggest a role for cerebral dysfunction in the etiology of their aberrant behavior.

Adult↗

PubMed1990

Effects of repeated temporary clipping of the middle cerebral artery on pial arterial diameter, regional cerebral blood flow, and brain structure in cats.

Temporary clipping of the major arterial trunk is an important maneuver to control excessive unexpected bleeding in neurosurgical operations; however, repeated temporary clipping can give rise to severe neurological deficits after surgery. The present study was performed to confirm and explain these clinical findings. Initially, a single 20-minute or 1-hour occlusion of the middle cerebral artery was performed in each of 5 cats. Pial arterial diameter was determined by video imaging, regional cerebral blood flow was measured by autoradiography, and cerebral edema and infarction were observed. In the 20-minute occlusion group, no abnormal changes were found 5 hours after recirculation. In the 1-hour occlusion group, pial arteries were dilated by 45%, and regional cerebral blood flow increased to more than twice the resting cortical values. The extent of cerebral edema was 41.2 +/- 7.5% (SE) and infarction was 34.5 +/- 9.5% (SE) of the hemisphere. In the second experiment, three 20-minute occlusions of the middle cerebral artery in a 1-hour interval were performed in 20 cats. In 10 of them, thiopental (40 mg/kg) was used to protect the brain. In the group without barbiturate treatment, pial arteries were dilated by 40% at the end of experiment, regional cerebral blood flow decreased to about 70% compared with single 20-minute occlusion, cerebral edema was 19.5 +/- 8.1% (SE), and infarction was 8.1 +/- 3.7% (SE) of the hemisphere. In the treated group, these were only trivial changes. The effect of repeated clipping may cumulatively cause brain damage, and barbiturates should be used whenever repeated clipping is necessary.

Animals↗

PubMedDate not supplied

[Effect on cardiac function of altered adenosine metabolism in rat brain structures in modelled hyperuricemia].

Experiments on 24 Wistar male rats were performed to clarify the role of central mechanisms in the onset of electrical instability of the heart due to disturbances in purine metabolism. The activity of the enzymes responsible for synthesis and conversion of adenosine-5-nucleotidase and adenosine deaminase in the sensomotor cortex, hypothalamus and hippocamp was studied. Changes in cardiac function were most severe in high levels of adenosine in the neurons of the sensomotor cortex, hypothalamus and hippocamp. Minimal changes occurred in low content of adenosine in the hypothalamus and hippocamp.

Adenosine↗

PubMed1990

[Changes in the flux frequency of the neuronal discharges of human subcortical brain structures related to the organization of motor acts].

16 Parkinsonian patients (6 females) with depth electrodes within striopallido-thalamic system implanted for diagnostic and therapeutic purposes, voluntarily participated in four psychological tests. Two groups of the pallidal and thalamic neuronal populations (response- and stimulus-related neuronal populations) were distinguished on the basis of evoked responses in the motor odd ball test. Response-related neurons were in turn separated into several subgroups according to their reactions in the delayed-response tasks. Some of these neuronal populations reacted preferentially to counting, some--to naming, some--to pressing button.

Brain↗

PubMed1992

Image processing for the study of brain structure and function: problems and programs.

Fundamental problems in the analysis of functional and structural imaging data include data transport, boundary identification (including manual tracing, edge detection, and tissue segmentation), volume estimation, three-dimensional reconstruction and display, surface and volume rendering, shape analysis, and image overlay. These problems require that research investigators have access to suitable methods of image analysis, implemented on a set of software programs, in order to conduct neuroimaging research. The authors describe a group of software programs designed to provide a comprehensive solution for these problems.

Brain↗

PubMedDate not supplied

[Organization of neuronal responses in the sensomotor cortex during simultaneous stimulation of brain structures].

It has been found on alert non-immobilized rabbits that paired stimulations of the medical lemniscus, the midbrain reticular formation and the pyramidal tract in different succession cause in the sensorimotor cortex the formation of a temporary connection by the parameters of single unit activity and evoked potentials. The temporary connection is manifested in dynamics of evoked responses and in the change of electrical activity at the moment of usual presentation of the second stimulus, if it is omitted. The inflow of impulse activity by different paths adds some peculiarities to the organization of the temporary connection. The leading role in the given model situation may belong to the non-specific system.

Animals↗