SEARCH · PubMed Health

Results for “LIMBIC SYSTEM”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed2005

Examining the gateway to the limbic system with diffusion tensor imaging: the perforant pathway in dementia.

Current treatments for Alzheimer's disease (AD) are only able to slow the progression of mental deterioration, making early and reliable diagnosis an essential part of any promising therapeutic strategy. In the initial stages of AD, the first neuropathological alterations occur in the perforant pathway (PP), a large neuronal fiber tract located at the entrance to the limbic system. However, to date, there is no sensitive diagnostic tool for performing in vivo assessments of this structure. In the present bimodal magnetic resonance imaging (MRI) study, we examined 10 elderly controls, 10 subjects suffering from mild cognitive impairment (MCI), and 10 AD patients in order to evaluate the sensitivity of diffusion tensor imaging (DTI), a new MRI technique, for detecting changes in the PP. Furthermore, the diagnostic explanatory power of DTI data of the PP should be compared to high-resolution MRI volumetry and intervoxel coherences (COH) of the hippocampus and the entorhinal cortex, two limbic regions also involved in the pathophysiology of early AD. DTI revealed a marked decrease in COH values in the PP region of MCI (right side: 26%, left side: 29%, as compared to controls) and AD patients (right side: 37%, left side: 43%, as compared to controls). Reductions in COH values of the PP region were significantly correlated with cognitive impairment. DTI data of the PP zone were the only parameter differing significantly between control subjects and MCI patients, while the volumetric measures and the COH values of the hippocampus and the entorhinal cortex did not. DTI of medial temporal brain regions is a promising non-invasive tool for the in vivo diagnosis of the early/preclinical stages of AD.

Aged↗

PubMed1976

Stereotactic surgery of the limbic system in epilepsy.

During the routine follow-up of results of stereotaxic surgery in the patients treated for behaviour disorders, it was found that some of them had a bonus relief from seizures, Out of 260 amygdalotomies, 54 hypothalamotomies and 5 thalamolaminotomies performed for behavioural problems, 107 patients suffered from associated seizure disorder. 76 of them (71%) showed considerable relief from seizures following surgery. This is detailed. It is hypothesized that probably these nuclei of the "limbic system" either initiate and/or propagate seizure activity. This view is supported by the "improvement" in EEG in addition to the clinical improvement seen in these patients.

Amygdala↗

PubMed1988

Are emotion and motivation localized in the limbic system and nucleus accumbens?

Groups of control rats without surgery or groups of rats prepared with surgical lesions of the septal nuclei, amygdala, cingulate cortex, accumbens nucleus, section of the fornix, or sham surgical operations, were tested in a simple autonomic conditioning situation (conditioned defecation). Control rats and rats with lesions of the accumbens nucleus were also tested in a straight alley maze under varying conditions of water deprivation. In general, the lesions had little effect except that amygdaloid damage impaired acquisition of conditioned defecation. The theory that 'emotion' and 'motivation' can be localized in the 'limbic system' and nucleus accumbens is discussed critically.

Animals↗

PubMed1985

Local cerebral metabolic effects induced by nigral stimulation following ventromedial thalamic lesions. II: Sensory motor, reticular and limbic systems.

The involvement of the ventromedial thalamic nucleus (VM) in mediating the local cerebral metabolic effects induced by unilateral substantia nigra (SN) electrical stimulation was investigated in the awake rat. Local cerebral glucose utilization (LCGU) was measured during ipsilateral SN-stimulation in VM-intact rats as well as in animals bearing 8 or 30 days old electrolytic VM-lesions, using the 14C-deoxyglucose quantitative autoradiographic method. In VM-intact rats, SN-stimulation enhanced LCGU in several bilateral components of the sensory motor, reticular, and limbic systems despite the lack of direct anatomical connections. Almost all these metabolic activations were no longer apparent one week following VM-lesion. In contrast, one month after the VM-injury, the above activations reappeared even more dramatically than in VM-intact animals especially on the contralateral side. It is concluded that SN-stimulation activates several brain regions of both hemispheres beyond the traditional motor areas, the role of the VM in mediating these activations is crucial, and the plasticity of the adult CNS allows for recovery of metabolic responsiveness in a disturbed system.

Afferent Pathways↗

PubMed1987

[Study of the connections of supposed diencephalic connections of the limbic system of the lizard using the technic of axonal transport of horseradish peroxidase].

Connections of the anterior thalamic (n. dorsolateralis anterior, n. dorsomedialis) and habenular nuclei in lizards Ophisaurus apodus were studied by means of HRP administration into these nuclei. It was shown that all nuclei have overlapping locations of afferent sources (basotelencephalic structures, nuclei of anterior and hippocampal commissures, lateral area of the hypothalamus, superior raphe nucleus) and overlapping projectional zones (mammillary complex, ventral tegmental area). Besides common connections, specific ones for separate nuclei were revealed: for n. dorsolateralis anterior-reciprocal connection with dorsolateral hypothalamic nucleus, for habenular nuclei-projection to the interpeduncular nucleus, for n. dorsomedialis-projection to the dorsal hypothalamic area. No mammillary afferents were found for the anterior thalamic nuclei. All the nuclei studied are considered as diencephalic relay links of pathways which can be compared with dorsal (for habenular nuclei) and ventral (for anterior thalamic nuclei) pathways of the limbic system in mammals.

Animals↗

PubMed1986

Anterograde transsynaptic transport of WGA-HRP in the limbic system of rat and monkey.

The lectin tracer, wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP), was injected into the entorhinal cortex in rat and monkey brains. Tracer labeling was followed in the entorhinal projection to dentate gyrus and hippocampus, i.e. along the perforant pathway. Besides labeling perforant pathway terminals in the outer two-thirds of stratum moleculare in the dentate gyrus, reaction product was also observed within stratum granulosum. We conclude that labeling of dentate granule cells was the result of anterograde transsynaptic transport of WGA-HRP. The evidence thus provides an example of anterograde transsynaptic transport: in the limbic system; and at an excitatory synapse.

Animals↗

PubMedDate not supplied

Cocaine and pseudococaine: comparative effects on electrical after-discharge in the limbic system of cats.

The effects of cocaine and its dextroisomer pseudococaine on electrical after-discharge (AD) evoked by electrical stimulation of the hippocampus or amygdala were studied in cats with electrodes implanted in the brain. Intravenous injection of cocaine (2.0 to 4.0 mg/kg doses) produced a suppressive effect on the AD while producing low-voltage fast waves (LVFWs) in the electrical activities of the brain (EEG) associated with behavioral excitation. In contrast, pseudococaine at the same dose as cocaine failed to show a significant suppressive effect on the AD except at high doses (5.0 mg/kg). Pseudococaine produced high-voltage slow waves (HVSWs) in the EEG associated with behavioral depression. A linear dose-response relationship was observed for the suppressive effect of cocaine on the AD. The results suggested that the limbic system may be involved as a primary site of action of cocaine in the central nervous system (CNS).

Amygdala↗

PubMed1988

Differential effects of competitive and non-competitive N-methyl-D-aspartate antagonists on glucose use in the limbic system.

The effects on cerebral glucose utilisation of 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP, a competitive N-methyl-D-aspartate (NMDA) receptor antagonist), and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801, a non-competitive NMDA receptor antagonist) have been examined in conscious rats. Cerebral glucose utilisation was assessed quantitatively with 14C-2-deoxyglucose autoradiography. MK-801 (0.05-5 mg/kg, i.v.) markedly increased glucose use in a number of limbic brain areas such as the mamillary body, anterior thalamic nucleus, posterior cingulate cortex and hippocampus. CPP (3-30 mg/kg, i.v.), in contrast, effected minimal alterations in glucose use in the limbic system. The functional consequences in vivo, as reflected in local cerebral glucose use, of competitive blockade of the NMDA receptor differ markedly from blockade with non-competitive antagonists.

Animals↗

PubMed1994

Savoxepine fails to selectively influence glucose metabolism in the rat limbic system.

The [14C]-2-deoxyglucose method was used to map the in vivo metabolic response of glucose to savoxepine, a novel tetracyclic cyano-dibenzoxepino-azepine. Savoxepine is reported to have higher affinity for dopamine (DA) receptors in the hippocampus than in the striatum and hence should have dose-dependent, anatomically selective actions. Two doses of savoxepine (0.05 mg/kg and 0.5 mg/kg) were compared with haloperidol (1 mg/kg) to test the hypothesis that low doses of savoxepine would display a selective action on limbic brain areas. Results failed to show that low dose savoxepine selectively modifies glucose utilization in the limbic system as previous biochemical studies suggested. In fact, low doses of the drug displayed a potent activity quite similar to haloperidol in effect and localization. The low dose did not produce significantly altered glucose metabolism in the nucleus accumbens or in the lateral habenular nucleus as observed with most other neuroleptics, suggesting a lack of antipsychotic action at this dose. Our findings demonstrate the difficulty of designing a neuroleptic with a preferential blockade of limbic DA receptors and point to the need for functional assessment of regional receptor binding differences.

Animals↗

PubMed2002

Selective impairment of reasoning about social exchange in a patient with bilateral limbic system damage.

Social exchange is a pervasive feature of human social life. Models in evolutionary biology predict that for social exchange to evolve in a species, individuals must be able to detect cheaters (nonreciprocators). Previous research suggests that humans have a cognitive mechanism specialized for detecting cheaters. Here we provide neurological evidence indicating that social exchange reasoning can be selectively impaired while reasoning about other domains is left intact. The patient, R.M., had extensive bilateral limbic system damage, affecting orbitofrontal cortex, temporal pole, and amygdala. We compared his performance on two types of reasoning problem that were closely matched in form and equally difficult for control subjects: social contract rules (of the form, "If you take the benefit, then you must satisfy the requirement") and precaution rules (of the form, "If you engage in hazardous activity X, then you must take precaution Y"). R.M. performed significantly worse in social contract reasoning than in precaution reasoning, when compared both with normal controls and with other brain-damaged subjects. This dissociation in reasoning performance provides evidence that reasoning about social exchange is a specialized and separable component of human social intelligence, and is consistent with other research indicating that the brain processes information about the social world differently from other types of information.

Adult↗

PubMed2004

Zac1 is up-regulated in neural cells of the limbic system of mouse brain following seizures that provoke strong cell activation.

Zac1, a new zinc-finger protein that regulates both apoptosis and cell cycle arrest, is abundantly expressed in many proliferative/differentiation areas during brain development. In the present work, we studied Zac1 gene expression and protein in experimental seizure models following i.p. injection of pentylenetetrazole (PTZ) or kainic acid (KA). Following KA treatment, an early and intense up-regulation of Zac1 is detected in the limbic areas, such as the hippocampus, cortex and amygdaloid and hypothalamic nuclei. Pre-treatment with MK-801, an antagonist of the NMDA receptors, fully blocks the effect of KA in the hippocampus, whereas it only attenuates KA-induced Zac1 up-regulation in the other areas of the limbic system. A reduced induction is obtained with PTZ-treated animals, specifically in the entorhinal and piriform cortices as well as in amygdaloid and hypothalamic nuclei. Thus, Zac1 is highly induced in the seizure models that generate strong neuronal stimulation and/or extensive cell damage (cell death), reinforcing its putative role in the control of the cell cycle and/or apoptosis. Moreover, strong induction is observed in the granular cells of the dentate gyrus (which are resistant to neurodegeneration) and in some glial cells of the dentate gyrus and subventricular zone, suggesting that Zac1 may be implicated in the mechanisms of neural plasticity following injury.

Animals↗

PubMed1979

The effect of amitriptyline and mianserine (Org. GB94) on food motivated behaviour of rats trained in a runway: possible correlation with biogenic amine concentration in the limbic system.

Rats on a 23 h food deprivation schedule were trained to run down a straight runway for a food reward. Neither amitriptyline nor mianserine had an effect on the running time for the food reward during the period of continuous reinforcement. However both antidepressants delayed the extinction of this response. It seems unlikely that this effect on extinction was due to an altered motivation for the food reward as amitriptyline significantly decreased the food intake of the experimental animals while mianserine increased the food intake throughout the period of the experiment. The observation that both these antidepressants reduce the speed of extinction of rewarded behaviour may be explicable in terms of observed changes in the concentration of biogenic amines in the limbic system.

Amitriptyline↗

PubMed1993

Viral infection and dissemination through the olfactory pathway and the limbic system by Theiler's virus.

Theiler's murine encephalomyelitis virus (TMEV) infection of mice can produce a biphasic disease of the central nervous system (CNS). Most susceptible strains of mice survive the acute infection and develop a chronic demyelinating disease. In this report, we analyzed the routes of spread of TMEV within the CNS of nude mice and target sites eventually infected in the CNS. Compared to the immunocompetent mouse, in which an antiviral immune response is mounted but virus persists, the nude mouse develops a severe encephalomyelitis due to the lack of functional T lymphocytes and provides a useful model for the study of viral dissemination. We demonstrated, by immunohistochemistry, the presence of viral antigen in defined regions of the CNS, corresponding to various structures of the limbic system. In addition, we found a different time course for viral spread using two different sites of intracerebral inoculation, ie, via the olfactory bulb or the cortex. Limbic structures were rapidly infected following olfactory bulb infection and then showed a decrease in viral load, presumably due to loss of target neurons. Using either route of infection, the virus was able to disseminate to similar regions. These results indicate that limbic structures and their connections are very important for the spread of TMEV in the brain. In the spinal cord, not only neuronal but hematogenous pathways were suspected to be involved in the dissemination of Theiler's virus.

Animals↗

PubMed1996

Involvement of the limbic system in multiple sclerosis patients with depressive disorders.

This study investigates the relationship between depression and both anatomic and cerebral blood flow abnormalities in multiple sclerosis (MS) patients. Ten nondepressed MS patients were compared with 10 depressed MS patients matched for age, sex, and functional disability. Both groups were evaluated by means of neuropsychological tests, magnetic resonance imaging, and single-photon emission tomography imaging. There was no difference between the two groups with regard to the global cognitive score. Magnetic resonance imaging data showed no significant differences in the number, side, location, and area of the demyelinating lesions between the two groups; however, regional cerebral blood flow asymmetries in the limbic cortex did distinguish the two groups. Analysis of variance showed a significant effect of depression on the perfusion asymmetries in the limbic cortex. Finally, perfusion asymmetries in limbic cortex significantly correlated with depression test scores. Our findings suggest that depression in MS patients could be induced by a disconnection between subcortical and cortical areas involved in the function of the limbic system.

Adult↗

PubMedDate not supplied

Anatomical "circuitry" in the brain mediating alcohol drinking revealed by THP-reactive sites in the limbic system.

The involvement of aldehyde adducts in the etiology of alcoholism continues to be supported by a number of experimental findings. These metabolites are synthesized endogenously from a condensation reaction of a biogenic aldehyde with a catechol- or indole-amine and act in the brain to augment or suppress the drinking of ethyl alcohol. When given by the intracerebroventricular route in an animal which does not prefer alcohol, certain tetrahydro-isoquinolines and beta-carbolines can augment significantly the voluntary intake of alcohol even in aversive concentrations. This paper describes the historical background and current status of the "Multiple Metabolite" theory of alcoholism. The recent identification of anatomical structures in the limbic-midbrain, limbic-forebrain of the Sprague-Dawley rat, which mediate changes in the intake of alcohol induced by tetrahydropapaveroline (THP) is also described. When injected in a low dose of 25 ng in a specific site, over a 3-day period, THP induces persistent increases in the intake of alcohol even in aversive concentrations. These THP-reactive sites comprise the substantia nigra, reticular formation, medial lemniscus, zona incerta, medial forebrain bundle, nucleus accumbens, olfactory tubercle, lateral septal nucleus, preoptic area, stria terminalis, and rostral hippocampus. A higher dose of 250 ng THP microinjected at homologous loci tends to inhibit the rat's self-selection of alcohol or exert no effect on drinking. Morphological mapping of histologically identified sites sensitive to THP revealed a distinct "circuitry" of neuronal structures overlapping both dopaminergic and enkephalinergic pathways. This "circuit" extends from the tegmental-nigral area of the midbrain rostrally to structures within the limbic-forebrain. When a THP-reactive structure, the N. accumbens, was lesioned by either of two neurotoxins, 6-hydroxydopamine or 5.7-dihydroxytryptamine, the rats' preference for alcohol increased sharply. This suggests that impairment of transmitter release, denervation supersensitivity or other perturbation of receptor function within this and other structures play a part in the aberrant drinking of alcohol. It is envisaged that a dopamine-enkephalin link underlies the mechanism for the onset, maintenance and permanency of alcohol preference generated by an aldehyde adduct. Finally, the "Two-Channel, Brain Metabolite" theory of alcoholism proposes that the transitory presence of an endogenously formed aldehyde adduct within cells of the brain causes a permanent perturbation of normal receptor processes and transmitter activity within synapses of specific structures of the limbic system. This theory thus explains the nature of the rewarding properties of alcohol as well as its complex addictive liability which is physiologically irreversible.

Alcohol Drinking↗

PubMed1982

Pseudopodial interdigitations between abutted nerve terminals: diffusion traps which occur in several nuclei of the rat limbic system.

Stimulation of the Torpedine ray electric organ can cause the loss of synaptic vesicles and the growth of pseudopodia from the nerve terminals (Boyne, A. F., and S. McLeod (1979) Neuroscience 4: 615-624). The latter embed themselves in corresponding indentations in abutted terminals. The geometry of these pseudopodial indentations (PSIs) can vary: (i) in length, (ii) in the extent of constriction of the base, and (iii) through a compound interaction between different pseudopodia extending in opposite directions. Examination of six rat brain nuclei in the limbic system has shown that their neuropil can be categorized according to the prevalence of either (i) nerve terminals indented by nerve terminal outgrowths (i.e. PSIs) or (ii) nerve terminals indented by dendritic outgrowths: these have been previously termed spinules. Clusters of simple PSIs were seen in the central nucleus of the amygdala, while base-constricted and compound forms were found in the globus pallidus and substantia nigra. Dendritic spinules were prevalent in the nucleus accumbens and the molecular layer of the hippocampus. In the CA4 hilar region of the hippocampus, large nerve terminals containing PSIs were found. The caudate neuropil appeared to be of mixed character in that the small terminals often had spinules but occasionally showed PSIs. Spinules have been recognized for many years and the possibility of their plasticity has been raised previously (Tarrant, S. B, and A. Routtenberg (1977) Tissue Cell 9: 461-473). The present report appears to be first detailed description of an alternative form of invasion which is known to be plastic in the elasmobranch electric organ. It is suggested that the extracellular space between the partners of a PSI could act as variable diffusion traps. If the involved boutons carry action potentials, then nonsynaptic release and accumulation of substances such as potassium, amino acids, and nucleotides may be expected during stimulation. Consequent direct or receptor-mediated effects on the membrane potential could influence transmission through adjacent synapses.

Amygdala↗

PubMed1980

[Cyclic adenosine-3',5'-monophosphate content in the limbic system structures of the rat brain on the administration of corticosteroids].

The effect of hydrocortisone and DOCA on the cAMP content in the hypothalamus, hippocampus and striate body of the rat brain was investigated. Single (determined after 1 and 24 hours) and repeated (7 days) hydrocortison administration in a dose of 5 mg/100 g body weight was accompanied by an increase in the cAMP concentration in the brain structures under study. Single administration of DOCA in a dose of 0.5 mg/100 g body weight did not produce any changes in the cAMP level in the structures of the rat brain limbic system; however, the dose of 2.5 mg raised the cAMP level. Prolonged administration of the hormone in the above doses dod not change the cAMP level in the brain structures. Only the hippocampus showed a 210% increase in the cAMP level during DOCA administration in a dose of 0.5 mg.

Animals↗

PubMed1996

The identification of a novel cDNA preferentially expressed in the olfactory-limbic system of the adult rat.

To analyze cell-specific brain gene expression, we have developed a PCR-based subtractive hybridization cloning method utilizing trace starting material, allowing isolation of novel genes expressed under specific conditions. Our previous studies indicated that local substantia nigra (SN) type 1 astrocytes elaborate an array of trophic molecules which support the survival of SN dopaminergic neurons. Therefore, the current study focused on astrocyte gene expression utilizing a type 1 astrocyte-enriched cDNA library. We report initial characterization of a novel cDNA, designated AT1-46, that is preferentially expressed in the olfactory-limbic system of the adult rat brain. Although AT1-46 is expressed widely in the periphery, it is regulated both developmentally and in a cell-specific fashion in the brain. Structurally, AT1-46 is predicted to encode a highly alpha-helical molecule with several domains of potential coiled coil formation, and exhibits a 28% amino acid sequence identity with the intermediate filament-associated protein, trichohyalin.

Amino Acid Sequence↗