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PubMed1985

Basic science and clinical aspects of procaine HCl as a limbic system excitant.

The literature in animals and humans which indicate that systemic procaine HCl activates limbic tissue is reviewed. Studies in cats which suggest that procaine excites limbic cells by reducing neural inhibition are then described. Evidence that power spectral analysis of high frequency EEG bands (omega or 31-55 cps) in the temporal cortical EEG reflects degree of limbic (amygdala) excitation in animals and humans is reviewed. Studies in cats are described which show that procaine selectively increases omega band activity in the amygdala and temporal cortex in a dose related fashion which parallels dose related increases in amygdaloid neural activity. Preliminary results of combining intravenous procaine and omega band analysis of scalp EEG in humans to predict therapeutic response to carbamazepine in borderline personality and affective disorder patients are then described. The effects of procaine on omega are compared to the effects of direct electrical stimulation of human limbic system in complex partial seizure patients undergoing assessment for temporal lobectomy. The results tentatively support the hypothesis that some psychiatric patients have hyperexcitable limbic systems, and those that do, show a positive behavioural response to carbamazepine.

Animals↗
PubMed1988

A unique membrane protein is expressed on early developing limbic system axons and cortical targets.

The limbic system-associated membrane protein (LAMP) is a 64 kDa protein that, in the adult brain, is present in cortical and subcortical regions comprising the limbic system (Levitt, 1984). The developmental expression of LAMP was studied in fetal rat brains to determine the specific patterns of distribution and the cellular elements that exhibit LAMP immunoreactivity. Light microscopic immunocytochemical analysis revealed that LAMP is expressed on neurons and their growing axons early in fetal development, at a time coincident with pathway formation and differentiation of limbic system nuclei. In the forebrain, where limbic system structures are heavily concentrated, immunoreactivity appears on subpopulations of axons in a temporal sequence that correlates with the time of formation of pathways carrying limbic system axons. Thus, staining is evident first at embryonic day (E) 15 on fibers within the internal capsule coursing from the diencephalon to cortex. LAMP immunoreactivity appears over the next 3 d in the anterior commissure, fornix, and corpus callosum. Ultrastructural immunocytochemical analysis reveals dense surface staining of fascicles of developing axons and growth cones. The axonal staining is transient, disappearing during the second postnatal week of development. In cerebral cortex, cells in presumptive limbic cortical regions such as lateral perirhinal sulcal cortex and prefrontal cortex are LAMP immunoreactive from the inception of the cortical plate. These cortical regions are clearly delineated from surrounding unstained nonlimbic areas as early as E15. Thus, LAMP expression in the cortex may represent one of the earliest markers of specific cytoarchitectonic areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1968

[The limbic system and the motivation process].

Understanding the part played by the limbic system in the shaping of overall behaviour is assisted by the previous study of that system's involvement in the mechanisms underlying certain sections of behaviour. a) Limbic structures contribute to the dynamic synthesis of contemporary information, by reason of their share in mechanisms: I. of modulatory central control in the production and transmission of sensory messages, 2. in the genesis of states of vigilance, especially the focussing of attention. On the other hand, they have an inhibitory role in somatic motility by way of progressive elimination of all inadequate motor response. b) Limbic structures participate in the elaboration of emotional states, in the initiation of both positive and negative reinforcement. That is to say they participate in the processes by which: I. "appetitive" or "aversive" significance is progressively conferred upon a given stimulus or situation, 2. behaviour is subjected to a positive or negative reinforcement, assuring its stabilization or its extinction. c) The comparison of the present situation with experience, enabling the organism to foresee the results of its behaviour; and similarly the comparison of results achieved with those anticipated, imply information storage, and the formation of lasting memory traces. It appears that the limbic system by integration of cognitive and affective components of sensory information, contributes to the compilation of experience which can be drawn upon in recognition or evocation. When the lasting results of different limbic lesions upon total behaviour are studied, it is clear that these effects are all the more profound as, among the motivational factors involved, those due to experience and to adaptation to environment, play the more important part. Behavioural deficits appear especially due to the absence of inhibition of certain inadequate responses, which results in a "maladaptation" of behavior as much towards present environmental conditions as to the experience of the organism. a) Regarding alimentary behaviour, the limbic system seems only to have importance in fixing the various individual attitudes towards feeding (competition, feeding habits, time to repletion, etc.). b) Sexually, experimental facts suggest that the limbic system plays an essential part in facilitation and especially selective inhibition which, by the exclusion of inadequate responses, may differentiate adult heterosexual conduct from ambivalent sexuality. Thus, in the adult, sexual behaviour can appear which is adapted to the environment, and consistent with the genetic sex and certain individual behavioural characteristics of the organism.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1997

Differential effect of haloperidol on release of neurotensin in extrapyramidal and limbic systems.

The effect of the antipsychotic drug haloperidol on extracellular neurotensin-like immunoreactivity was investigated by microdialysis and compared with the time-dependent response of tissue neurotensin-like immunoreactivity content in brain structures containing dopamine nerve cell bodies and terminals. A single administration of haloperidol (1 mg/kg) increased the extracellular neurotensin-like immunoreactivity levels in nucleus accumbens as measured by microdialysis, but decreased its extracellular concentration in the caudate regions surrounding the probe. The same treatment increased the tissue content of neurotensin-like immunoreactivity in both the nucleus accumbens core and all caudate regions examined within 24 h after the injection. Interestingly, although the neurotensin-like immunoreactivity concentration in the substantia nigra was not altered by the haloperidol treatment, neurotensin-like immunoreactivity levels decreased significantly in the ventral tegmental area. These findings suggest that varied neurotensin systems are associated with nigrostriatal and mesolimbic dopamine pathways and these systems have different responses to haloperidol. The changes in the release of neurotensin may contribute to altered caudate and accumbens neurotensin-like immunoreactivity tissue content induced by haloperidol treatment, but other factors, such as variation in synthesis also likely influence these effects. Differential actions of haloperidol on neurotensin release might be due to regional differences in dopamine or sigma receptor subtypes associated with the neurotensin-containing neurons.

Animals↗
PubMed1977

[Relationship between the limbic system and gonadal function. 2. Quantifiable prepuberal differentiation of medial cortical amygdaloid nuclei].

In juvenile female rats beteen the 21st and 26th days of age, the neurons of the medial and cortical amygdaloid nuclei undergo a highly significant karyovolumetrically measurable activation which, however, partially declines almost immediately. Such prepuberal variation of activity was found to be correlated with age-dependent effects of direct interventions with these nuclear regions upon the hypothalamy-pituitary-gonadal axis, e.g. implantation of oestradiol benzoate, stimulation or lesioning. This basically, is a quantitatibe-morphological confirmation of an assumption that had been derived earlier from experimental studies, according to which the mediocortical part of the amygdala undergoes in the prepuberal period a functional muteration or differentiation which is specific and related to puberty and gonadal functions (Döcke, 1976a, b; Döcke et al., 1976).

Aging↗
PubMedDate not supplied

Effect of cocaine and amphetamine on biosynthesis of proenkephalin and prodynorphin in some regions of the rat limbic system.

A vast body of evidence points to the role of the limbic system in the mechanism of drug dependence. Opioid peptides localized in the limbic system may play a role in central effects of substances of abuse. The goal of the present study was to investigate the influence of acutely and chronically administered drugs of abuse, cocaine and amphetamine on biosynthesis of prodynorphin and proenkephalin in the rat amygdala, the structure involved in the mechanism of drug addiction. Acute injection of cocaine (20 mg/kg ip every hour for 3 h) or amphetamine (2.5 mg/kg) did not changed or decreased the level of proenkephalin mRNA in the central nucleus of the amygdala. In contrast, the level of prodynorphin mRNA was significantly increased in this structure after cocaine. Repeated cocaine administration (20 mg/kg ip every hour for 3 h, for 5 days) had no effect on the proenkephalin and prodynorphin mRNA in the central nucleus of the amygdala. Chronic amphetamine (2.5 mg/kg twice daily for 5 days) administration decreased proenkephalin and increased prodynorphin mRNA level in the central nucleus of the amygdala (at 24 and 48 h). Moreover, significant increase in prodynorphin mRNA level was observed in the hippocampal dentate gyrus after acute (cocaine) and chronic (cocaine, amphetamine) administration of the psychostimulants. The observed adaptive changes in the activity of two opioid systems in two structures of the limbic system, central nucleus of amygdala and hippocampus, may contribute to the neurochemical mechanism of drug addiction after psychostimulants. These studies also indicate that the changes in opioid gene expression in the central nucleus of the amygdala are not parallel to those observed in the nucleus accumbens after cocaine and amphetamine, which suggests that peptidergic systems in the structures of extended amygdala might be regulated by different neurochemical mechanisms after psychostymulant administration.

Amphetamine↗
PubMed1995

[Effect of fluvoxamine, a new antidepressant drug, on monoamine dynamics in the rat cerebral limbic system and its pharmacological characteristic].

The effect of fluvoxamine (FLU) on the amine dynamics in serotonergic, noradrenergic or dopaminergic nervous systems in the rat cerebral limbic system was investigated, with reference to the pharmacological characteristics of FLU. Following single oral administration of 30 and/or 60 mg/kg FLU, significant decreases in the 5-hydroxyindole-3-acetic acid (5-HIAA)/serotonin (5-HT) ratios in the amygdala and hippocampus and the 4-hydroxy-3-methoxyphenylglycol (MHPG)/norepinephrine (NE) ratio in the amygdala were produced. FLU at 15 mg/kg, p.o. also caused a significant increase in MHPG/NE ratio in the hippocampus. On the other hand, imipramine (IMI) at 30 mg/kg, p.o. induced significant decreases in 5-HIAA/5-HT ratio in the hippocampus, MHPG/NE ratios in the amygdala and hippocampus, and 3,4-dihydroxyphenylacetic acid (DOPAC)/dopamine (DA) ratios in the amygdala, hippocampus and septum. The 5-HIAA/5-HT ratios in the amygdala and hippocampus and the MHPG/NE ratio in the septum were significantly decreased after repeated oral administration of 30 mg/kg FLU twice daily for 14 days, but the MHPG/NE ratio in the amygdala was increased. In the septum, DOPAC/DA ratio was significantly decreased following repeated administration of IMI at 30 mg/kg, p.o. These findings suggest that FLU inhibits 5-HT turnover in the amygdala and hippocampus as a result of the interference with the neuronal re-uptake mechanism for 5-HT. Also, FLU has an effect on NE turnover in the cerebral limbic system, and the effect may appear in connection with a change in the interaction of nervous systems.

Administration, Oral↗
PubMed1983

The pseudopsychopathic personality and the limbic system.

The psychiatry of the limbic system has for a variety of reasons been a neglected field of study. There is a pseudopsychopathic syndrome which is characterized by sham rage-like reactions, emotional and social instability, aggressive behavior (at times), cognitive disturbances described as a special form of incoherence, abnormal social behavior in the form of social adhesiveness, carelessness and a certain proneness to criminality. All of these phenomena are stressed by alcohol even in small amounts. Normally the abnormality of the patient is not recognized as such neither by the patient nor by his doctor, but seen as seemingly normal personality traits.

Aggression↗
PubMed1997

The limbic system: an anatomic, phylogenetic, and clinical perspective.

The limbic system is the border zone where psychiatry meets neurology. The authors provide a model of limbic function that combines phylogenetic, anatomic, functional, and clinical data to interpret diseases relevant to neuropsychiatry. They provide evidence supporting two major divisions in the limbic system: a paleocortical division with the amygdala and orbitofrontal cortex at its center, and an archicortical division with the hippocampus and cingulate cortex at its center. The implicit integration of affect, drives, and object associations is the function of the paleocortical limbic division; explicit sensory processing, encoding, and attentional control is the function of the archicortical limbic division. The two work in concert to integrate thought, feeling, and action. Understanding their development and organization informs us about how best to care for our patients.

Animals↗
PubMedDate not supplied

[A general model of the limbic system and basal ganglia: applications to schizophrenia and compulsive behavior of the obsessive type].

The paper presents a model of the behavioural functions and information processing discharged jointly by the limbic system (especially, the hippocampal formation and amygdala) and the basal ganglia (both the dorsal and ventral striatal systems). In general terms, the limbic system plus basal ganglia act as a mechanism for the attainment of goals. The sensory aspects of this overall goal-direction function (recognition of goals and evaluation of the outcomes of action) are dealt with in the limbic system; the motor aspects (establishment and execution of motor programs), in the basal ganglia. The model is applied to an understanding of the neuropsychology of schizophrenia (in particular, positive psychotic symptoms) and obsessive-compulsive disorder. In both cases, emphasis is placed on the interaction between the limbic system and the basal ganglia.

Basal Ganglia↗
PubMed2001

Spontaneous confabulation, reality monitoring, and the limbic system--a review.

Patients with anterior limbic damage may present a distinct syndrome, spontaneous confabulation: they fail in common memory tests, act on the basis of previous habits rather than currently relevant memories, produce confabulations composed of elements of past true events, are disorientated, and are absolutely convinced about the veracity of their perceived reality. Spontaneous confabulation is independent of other false memories, such as, provoked confabulations or illusory recognition. Studies showed that spontaneous confabulators fail to suppress (inactivate) evoked memories that do not pertain to ongoing reality. Rehabilitation differs from other memory failures. Prognosis depends on the lesion site, but recovery is always associated with recovery of this suppression capacity. Lesions typically involve the posterior medial orbitofrontal cortex or its connections in the basal forebrain. Imaging and evoked potential studies in healthy subjects support the idea that the anterior limbic system provides a reality monitoring mechanism which selects memories of current relevance by suppressing (inactivating) currently irrelevant memories. This mechanism appears to adjust the cortical representation of activated memories before their content is recognised and consolidated. Comparison with animal studies suggests that human reality monitoring is a property of the brain's reward system.

Delusions↗
PubMed2005

Limbic system mechanisms of stress regulation: hypothalamo-pituitary-adrenocortical axis.

Limbic dysfunction and hypothalamo-pituitary-adrenocortical (HPA) axis dysregulation are key features of affective disorders. The following review summarizes our current understanding of the relationship between limbic structures and control of ACTH and glucocorticoid release, focusing on the hippocampus, medial prefrontal cortex and amygdala. In general, the hippocampus and anterior cingulate/prelimbic cortex inhibit stress-induced HPA activation, whereas the amygdala and perhaps the infralimbic cortex may enhance glucocorticoid secretion. Several characteristics of limbic-HPA interaction are notable: first, in all cases, the role of given limbic structures is both region- and stimulus-specific. Second, limbic sites have minimal direct projections to HPA effector neurons of the paraventricular nucleus (PVN); hippocampal, cortical and amygdalar efferents apparently relay with neurons in the bed nucleus of the stria terminalis, hypothalamus and brainstem to access corticotropin releasing hormone neurons. Third, hippocampal, cortical and amygdalar projection pathways show extensive overlap in regions such as the bed nucleus of the stria terminalis, hypothalamus and perhaps brainstem, implying that limbic information may be integrated at subcortical relay sites prior to accessing the PVN. Fourth, these limbic sites also show divergent projections, with the various structures having distinct subcortical targets. Finally, all regions express both glucocorticoid and mineralocorticoid receptors, allowing for glucocorticoid modulation of limbic signaling patterns. Overall, the influence of the limbic system on the HPA axis is likely the end result of the overall patterning of responses to given stimuli and glucocorticoids, with the magnitude of the secretory response determined with respect to the relative contributions of the various structures.

Animals↗
PubMed1997

The limbic system. An overview of the anatomy and its development.

The limbic system has a pivotal role in attention, memory, and the emotions. The limbic lobe comprises four C-shaped arches stretching from the medial surface of the frontal lobe to the temporal pole. The anatomic relationships are elegantly demonstrated by MR imaging. This article provides an overview of the development and complex anatomy of the limbic system.

Amygdala↗
PubMed2002

Limbic system function and dream content in university students.

This study explored the relationship between limbic system function and threatening dream content. Recently it has been proposed that dreams are an evolutionary mechanism designed to facilitate the rehearsal of coping strategies in dangerous situations. It is known that the limbic system is active both during times of threat and during REM sleep. Therefore, it was hypothesized that individuals with relative limbic hyperfunction, as indexed by increased scores on the Limbic System Checklist (LSCL-33), would report more threatening dream content. The data of the present research confirmed the hypothesis.

Adolescent↗
PubMed2003

Stress and plasticity in the limbic system.

The adult nervous system is not static, but instead can change, can be reshaped by experience. Such plasticity has been demonstrated from the most reductive to the most integrated levels, and understanding the bases of this plasticity is a major challenge. It is apparent that stress can alter plasticity in the nervous system, particularly in the limbic system. This paper reviews that subject, concentrating on: a) the ability of severe and/or prolonged stress to impair hippocampal-dependent explicit learning and the plasticity that underlies it; b) the ability of mild and transient stress to facilitate such plasticity; c) the ability of a range of stressors to enhance implicit fear conditioning, and to enhance the amygdaloid plasticity that underlies it.

Amygdala↗
PubMed2000

Bilateral astrocytoma involving the limbic system precipitating disabling amnesia and seizures.

Astrocytomas involving the limbic system are usually unilateral in nature. We report a very unusual case where a low-grade astrocytoma originating in the left temporal lobe spread to the right hippocampus through the hippocampal commissure to cause disabling amnesia and seizures. Some improvement in the memory deficit was facilitated by identification of complex partial status epilepticus. EEG should be performed in all patients with lesions of the limbic system and neuropsychological problems if ongoing seizure activity is not to be missed.

Adult↗
PubMed1995

The limbic system of tetrapods: a comparative analysis of cortical and amygdalar populations.

Recent studies of the limbic system of tetrapods have made data available that challenge some of the long-held tenets of forebrain evolution. Using the basic principle of parsimony--that the best hypotheses concerning homologies are those requiring the fewest number of evolutionary changes--we have reevaluated comparisons of tetrapod limbic systems. Given the current data, the following points appear to be justified: (1) the common ancestors of reptiles and mammals had a well-developed limbic system in which the basic subdivisions and connections of the amygdalar nuclei were established; (2) the ventral part of the lateral pallium in amphibians appears to be a single structure which corresponds to at least four areas in reptiles: centromedial DVR, ventral anterior amygdala, lateral amygdala, and part of the lateral cortex; (3) the medial pallium in amphibians appears to be homologous with the dorsal and medial cortices in reptiles and with the general and hippocampal cortices in mammals: (4) the cortical targets of the main olfactory bulb in reptiles and mammals appear to be homologous, and their common ancestor probably had a corresponding olfactory pallial field; (5) the targets of the accessory olfactory bulb in amphibians, reptiles, and mammals appear to be homologous, with the exception of nucleus sphericus in reptiles, which lacks an obvious homologue in non-reptiles.

Amphibians↗