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PubMed1983

Influences of the limbic system on hypothalamo-neurohypophysial system.

(1) Effects of stimulations of various limbic structures (the olfactory bulb, olfactory tubercle, prepyriform cortex, endopyriform nucleus and various parts of amygdaloid nuclei) on the neurosecretory neurons in the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus were studied. All regions stimulated received strong inputs from the olfactory bulb. (2) Out of 195 "identified' neurosecretory neurons tested one-half or more (49-74%, depending on the structures stimulated) were inhibited by stimuli consisting of 1-3 short pulses. The inhibition occurred immediately after the stimulus in approximately one-fifty of all inhibited neurons, in the remaining four-fifths inhibition occurred after more than 20 ms latency. Inhibition of neurosecretory neuron activity lasted for several hundred milliseconds, often followed by clear post-inhibitory excitation or rebound. (3) In 23 neurons, a distinct "evoked' response of brief duration occurred with a 30 ms latency following stimulation of the lateral and medical amygdala, olfactory tubercle and prepyriform cortex. In another 17 neurons, a general increase in background activity with a longer latency (50-100 ms) occurred following stimulation of nearly all amygdaloid nuclei, olfactory tubercle and the pyriform cortex: lateral amygdala stimulation caused an excitation of the largest proportion of neurosecretory cells (30%) while none was excited by stimulation of the olfactory bulb and endopyriform cortex, except those occurring as post-inhibitory excitation. (4) There was a convergence of afferent impulses on single neurosecretory cells. A large proportion (42%) of the neurons received inputs from 2 to 4 limbic regions. (5) Neurosecretory cells which were influenced by limbic stimuli were also inhibited by baroreceptor activation and excited by osmotic stimulation. "Unidentified' neurons within SON and PVN and "atypical neurosecretory cells' (those responding to pituitary stalk stimulation with varying latencies) were also affected by the forebrain stimulation; some of these were also affected by an osmotic stimulus. A part of this group may send their axons to the median eminence.

Action Potentials↗
PubMed1983

The limbic system and aggression in humans.

This paper reviews the clinical literature relevant to the association between aggressive behavior and the limbic system in humans. Specific areas of review include aggressive behavior related to: (1) naturally occurring and iatrogenic brain lesions; (2) electrical disturbances; (3) pharmacologic intervention; and (4) central neurochemical concentrations which may implicate limbic lobe involvement.

Aggression↗
PubMed2000

Modulation of epileptiform discharges in the rat limbic system in vitro by noradrenergic agents.

Application of bicuculline (20 microm) in a horizontal slice preparation of the rat limbic system induced epileptiform discharges ('bursts') that spread from the hippocampus to the entorhinal cortex (EC) and the basolateral amygdala (BLA). These bursts were time locked, with the CA3-CA2 regions discharging first at a 0.1+/-0. 008Hz (n=30 slices) frequency, followed after 27+/-3 ms by the superficial layers of the EC and after 44.3+/-3 ms by the BLA. Application of 50 microM noradrenaline (NA) for 4 min reduced the burst frequency to 40% of its initial value. Pharmacological study of NA action on burst frequency revealed that it consisted of a beta adrenoreceptor-mediated increase and an alpha(2) adrenoreceptor-mediated decrease of epileptiform bursting frequency.

Adrenergic Agonists↗
PubMed1986

Differential distribution of neurotransmitter amino acids from the limbic system of aggressive and non-aggressive bull strains.

The amino acid content of crude synaptosomal fractions from the limbic system and related CNS regions showed significant differences between the aggressive Spanish fighting-bull and the non-aggressive Friesan bull breeds. Neurotransmitter amino acids (glutamate, aspartate, GABA and glycine) were the most unequally distributed. A higher ratio of excitatory to inhibitory neurotransmitter amino acids was always found in all the CNS regions studied in the aggressive breed. The concentrations of five non-transmitter amino acids (threonine, alanine, serine, leucine and isoleucine) showed minor variations between both studied bull strains and cannot be ascribed to differences in central energy metabolism. The results are explained in terms of a possible relationship between the amino acid neurotransmitter levels and the innate aggressiveness of the Spanish fighting-bull.

Aggression↗
PubMed1985

Basal ganglia and limbic system pathology in schizophrenia. A morphometric study of brain volume and shrinkage.

The volume of several parts of the basal ganglia and of the limbic system was measured by planimetry of myelin-stained serial sections in postmortem brains of 13 schizophrenic patients and nine control cases. The medial limbic structures of the temporal lobe (amygdala, hippocampal formation, and parahippocampal gyrus) and the pallidum internum were significantly smaller in the schizophrenic group, whereas the pallidum externum showed only a modest trend toward volume reduction. The volumes of the putamen, nucleus caudatus, nucleus accumbens, and the bed nucleus of the stria terminalis did not differ between patients and controls. The volume reductions of the limbic temporal structures and of the pallidum internum of schizophrenics are interpreted as degenerative shrinkages of unknown etiology.

Adult↗
PubMed1998

[Effects of glutamate, glutamate receptor in limbic system and hypothalamus on hypothalamus-pituitary-adrenal axis after rats MCAO].

OBJECTIVE: To investigate the features of activity changes of glutamate(Glu), glutamate receptors(GluR) in hippocampus and hypothalamus during rats middle cerebral artery occlusion (MCAO) or reperfusion. METHODS: Using radio-legend binding assay of receptor (RBA), high-performance liquid chromatography (HPLC) and hybridization in situ and radioimmunometric assay, (RIA), we determined the dynamic changes of Glu content, GluR capacity and it's Kd in cell membrane from the hippocampus of the ischemic brain and the hypothalamus CRHmRNA expression levels in every brain areas and ACTH concentrations in plasma at different time after middle cerebral artery occlusion(MCAO) or reperfusion. RESULTS: Glu content rapidly increased in the hippocampus and the hypothalamus at 15 minutes after MCAO, and reached the peak values at I1 h, and rapidly decreased to the basic-line level after reperfusion. Glu content IR24 h to IR48 h, was elevated again moderately, and declined slowly 48 hours after reperfusion. The GluR was down-regulated and the affinity enhanced in during the ischemic period. During the reperfusion period, the GluR was typically up-regulated. The CRHmRNA expressive levels were markedly enhanced in the tempol cortex, the hippocampus and the hypothalamus at I1 h, and kept to IR96 h, the ACTH concentration in the plasma increased relatively. In the peak time of reperfusion, the Glu content of hypothalamus was positively corrected with CRHmRNA expressive positive cell amounts of the hypothalamus. CONCLUSION: CRH may aggravate ischemic neuronal damage, and Glu participates in the pathogenesis of HPA axis be excited strongly and may be an important impel factor for ACI specially condition.

Animals↗
PubMed2001

Neurosyphilis showing transient global amnesia-like attacks and magnetic resonance imaging abnormalities mainly in the limbic system.

We report a case of neurosyphilis with transient global amnesia (TGA)-like attacks on the first presentation. MRI abnormalities in bilateral limbic systems, including a few lesions in the basal ganglia and thalamus, were identified. Depression and dementia became apparent, accompanied by a high treponemal antibody titer and mild cortical atrophy. Antisyphilitic therapy brought about mild improvement, and the MRI abnormalities decreased.

Adult↗
PubMed1984

Maturation of kainic acid seizure-brain damage syndrome in the rat. III. Postnatal development of kainic acid binding sites in the limbic system.

The progressive appearance of [3H]kainic acid binding sites with age has been studied in membrane suspensions prepared from various regions of the rat limbic system, and by autoradiography. Binding sites with fast dissociation rate appeared earlier than binding sites with slow dissociation rate. Scatchard analysis demonstrated apparent receptor heterogeneity for both subclasses. High affinity components were detected in the hippocampus as early as 10 days after birth, but in the amygdala + piriform lobe were found only towards the end of the third week, when animals also respond to parenteral kainic acid, for the first time, with limbic seizures accompanied by metabolic activation of the amygdala. Slice autoradiography revealed distinct labelling of the hippocampal CA3 region by postnatal day 10. A comparison with the ontogenesis of the kainic acid-induced seizure-brain damage syndrome suggests a role of high affinity receptors as mediators of metabolic nerve cell activation by kainic acid. However, this receptor interaction per se does not result in neuronal damage to the vulnerable region of the Ammon's horn, which will only occur at an age when also the amygdala is activated by the neurotoxin.

Age Factors↗
PubMed2002

Limbic system perfusion in Alzheimer's disease measured by MRI-coregistered HMPAO SPET.

The goal of this study was to perform a systematic, semi-quantitative analysis of limbic perfusion in patients with Alzheimer's disease (AD) using coregistered single-photon emission tomography (SPET) images aligned to magnetic resonance (MR) images. Limbic perfusion in 40 patients with mild to moderate AD was compared with that of 17 age-, sex-, and education-matched normal controls (NC). HMPAO SPET scans and 3D T1-weighted MR images were acquired for each subject. Structures of the limbic system (i.e. hippocampus, amygdala, anterior thalamus, hypothalamus, mamillary bodies, basal forebrain, septal area and cingulate, orbitofrontal and parahippocampal cortices) were traced on the MR images and transferred to the coregistered SPET scans. Perfusion ratios for all limbic regions were calculated relative to cerebellar perfusion. General linear model multivariate analysis revealed that, overall, limbic structures showed significant hypoperfusion (F=7.802, P<0.00001, eta (2)=0.695 ) in AD patients compared with NC. Greatest differences (d > or = 0.8) were found in the hippocampus, as well as all areas of the cingulate cortex. Significant relative hypoperfusion was also apparent in the parahippocampal cortex, amygdala/entorhinal cortex, septal area and anterior thalamus, all of which showed medium to large effect sizes (d=0.6-0.8). No significant relative perfusion differences were detected in the basal forebrain, hypothalamus, mamillary bodies or orbitofrontal cortex. Logistic regression indicated that posterior cingulate cortex perfusion was able to discriminate AD patients from NC with 93% accuracy (95% sensitivity, 88% specificity). The current results suggest that most, but not all, limbic structures show significant relative hypoperfusion in AD. These findings validate previous post-mortem studies and could be useful in improving diagnostic accuracy, monitoring disease progression and evaluating potential treatment strategies in AD.

Aged↗
PubMed1982

Mental phenomena induced by stimulation in the limbic system.

Direct electrical stimulation of any limbic sector may evoke a visceral sensation or an emotion, usually fear or anxiety. Vivid formed dream- or memory-like hallucinations, or intense feelings of familiarity, may be evoked from the hippocampal formation and amygdala. Conversely, amnesia may result from stimulation-induced bilateral disruption of the same region. Cingulate gyrus stimulation near the supplementary motor cortex may evoke partially adaptive movement sequences, or may interfere with the performance of movements. In general, those phenomena are not due to epileptic pathology, nor to gross spread of activation. The particular response evoked is not related to the precise electrode location, but rather to the patient's psychological traits and concerns. Thus, there is no direct relationship between specific mental contents and the activation of particular limbic neurons. Limbic stimulation appears to produce deep mental alterations whose manifestation at the surface of awareness, or in specific movements, is defined by the ongoing context.

Affect↗
PubMed1997

Autoradiographic determination of changes in opioid receptor binding in the limbic system of the Columbian ground squirrel at different hibernation states.

To localize and quantify the state-dependent changes in various opioid receptor subtypes in the limbic system of non-hibernating and hibernating Columbian ground squirrels, quantitative receptor-binding autoradiography was used. Compared to the non-hibernating animals, the binding density of [3H]-[D-Pen2,5]-enkephalin (DPDPE) to the delta receptor in the lateral septum, CA3, and the hippocampal fissure of the hippocampal formation was significantly decreased in the hibernating ground squirrels. A significant reduction in the binding density of [3H]-[D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin (DAGO) to mu receptor was also observed in the medial septum and the CA3 region of the hippocampus of the hibernating animals. In contrast, a decrease in [3H]ethylketocyclazocine (EKC) binding to the kappa receptor was only observed in the claustrum and CA3 of the hippocampus during hibernation. The differential changes in binding to various opioid receptors suggest that different opioid subtypes may exert different physiological roles in regulating the specific states (entrance, maintenance and arousal) of a hibernation bout.

Animals↗
PubMed1976

[Relationship between the limbic system and gonadal function. Quantifiable morphokinesis of the medial amygdaloid nucleus with reference to the estrous cycle].

Karyovolumetric investigation showed that in rat the neurons of the limbic system which are associated with the Pars caudalis of the nucleus amygdaloideus medialis followed a morphokineses which was quantifiable in relation to the oestral cycle. The cell nuclei differed significantly in volume between cycle phases, which was interpreted as morphological correlation between variations in neuronal activity of metabolism. It was thought to be another point in support of the relationship between the amygdala and central-nervous structures of the cerebro-pituitary-gonadal axis.

Amygdala↗
PubMed1983

[Effect of experimental changes in thyroid function on oxidative metabolism and glutamate dehydrogenase activity in the limbic system of the rat].

The oxidative metabolism and GDH activity has been studied in the following regions of the brain: frontal cortex, as tissue control, adenohypophysis, hypothalamus and limbic system in adult male rats subjected to alterations of the thyroid function due to excess (by hyperthyroidism with L-thyroxine and thyrotoxicosis with Tri-iodothyronine) or defect (chronic hypothyroidism by thyroidectomy, 131-I treatment and low iodine diet). A different influence of the H.T. was observed in these animals according to the areas studied and the experimental situation induced. All this seems to indicate an oxidative metabolic pattern peculiar to each area of the brain following H.T. administration. On the other hand, the decrease of the QO2 in chronic hypothyroidism in the majority of the areas studied is remarkable. In GDH results activity increased or decreased depending on the absence or presence of thyroid hormones.

Animals↗