Physiological Connections Research Articles

Fast (beta) rhythms in the hippocampus: a review.

Spontaneous or evoked brain activity in the hippocampus showed a 20-70 Hz beta rhythm under some conditions, typically during behavioral activation and accompanied by a theta rhythm. Beta rhythms are generated locally, perhaps by a recurrent feedback loop involving pyramidal cells and inhibitory interneurons. Modulation of the local circuit and rhythm by cholinergic inputs has also been demonstrated. Under some behavioral states, neural impulses modulated at the beta frequency may transmit preferentially through the trisynaptic circuit in the hippocampus. It is suggested that the beta rhythm may serve to establish transient physiological connections, reflected in coherence at the beta frequency, among neurons in the hippocampus and related structures. Thus, the beta rhythm may play an essential role in hippocampal function.

Functional architecture of hippocampus studied with an optical method, II. Physiological connection between entorhinal cortex and hippocampal formation

Functional architecture of hippocampus studied with an optical method, II. Physiological connection between entorhinal cortex and hippocampal formation

Functional architecture of hippocampus studied with an optical method, I. Physiological connection in hippocampal formation

Functional architecture of hippocampus studied with an optical method, I. Physiological connection in hippocampal formation

Substitutionstherapie im Klimakterium: Soll bei hysterektomierten Frauen auf Progestogene verzichtet werden?

The replacement therapy in postmenopausal women is seen to be for transformation of the oestrogen-stimulated endometrium only, which does not apply to hysterectomised women. Because of the influence of estrane on lipids, one often advises against a replacement therapy with progestogens in hysterectomised women. With increasing knowledge of encountered extragenital functions of sexual steroids, the latter is questionable, if natural progesterone is given, which is (said to be) lipid-neutral, performing the function of the progestogens, which is quite more than reproduction only, more efficiently than estrane or gonane. Due to the competitive blocking of aldosterone the effect of progesterone is sodium-diuretic and diuretic, being as important as the therapy of climacteric complaints, as well as the consequence, which is the result of the physiological connection between progesterone and encephalics. Moreover, the effect of the progestogens is to tonicise the vascular system and is linked to a number of intestinal hormones in order to adjust their function. Therefore, progesterone seems to perform a great variety of extragenital functions. Menopausal women should not be deprived of the benefits of these functions within the framework of a replacement therapy.

Histo-chemical investigation on Fennel. Physiological connection between terpen's nature and histological structure of secretory apparatus (3)

Histo-chemical investigation on Fennel. Physiological connection between terpen's nature and histological structure of secretory apparatus (3)

Histo-chemical investigations on fennel. Physiological connection between terpen's nature and histological structure of secretory apparatus (2)

Histo-chemical investigations on fennel. Physiological connection between terpen's nature and histological structure of secretory apparatus (2)

Histo-chemical investigation on fennel. Physiological connection between terpen's nature and histological structure of secretory apparatus (1)

Histo-chemical investigation on fennel. Physiological connection between terpen's nature and histological structure of secretory apparatus (1)

Ex Vivo Perfusion for Accurate Assessment of Liver Graft Viability in Dogs

A new type of ex vivo liver perfusion model (EVPM) was developed. The system includes a physiological porto-portal connection, using a centrifugal pump and an aorto-aortal connection, through a heparin-coated tube. Ten pairs of mongrel dogs, weighing 13-20 kg, were used. Grafts of the liver procured from donors were perfused on the EVPM for 3 h. These grafts were divided into two groups: group A (n = 5), nonpreserved graft; group B (n = 5), 8-h graft preserved with lactated Ringer's solution (4 degrees C). The orthotopic liver transplantation (OLTx) series with the nonpreserved graft was reviewed, and dogs surviving for over 7 days following OLTx, group C (n = 5), were selected for liver grafts in the actual OLTx. In comparison with groups A and C, no difference was noted among enzyme levels (sGOT, sGPT, LDH) or in the recovery rate of ATP content in the graft liver tissue after revascularization. There were significant differences between group A and group B after revascularization. This simple and physiological EVPM accurately reflects graft function and hemodynamics in the actual OLTx. Graft viability, as a substitute for OLTx, in large animals can be reliably assessed. This EVPM is expected to contribute to research on events related to liver transplantation.

Structure of a tonically transmitting synapse between identified interneurone in the locust brain.

The ultrastructure and distribution of synapses between large second-order and third-order neurones of a locust ocellus are described. Pairs of neurones, shown by physiological tests to be connected by a tonically transmitting, excitatory connection, have been injected with hexamminecobaltic ions, which allows their profiles to be recognised with electron microscopy. The synapses are made in the lateral ocellar tract, between the axons of some of the second-order neurones and a network of fine processes from the third-order neurone. A physiological connection is composed of several thousand discrete anatomical synapses. Each anatomical synapse is composed of a presynaptic density associated with a cloud of round, electron-lucent vesicles overlying an intercellular cleft. Parallel with the presynaptic density is a row of omega-shaped invaginations of the presynaptic plasmalemma. The synapses are diadic and are close to synapses from small, unidentified neuronal profiles onto the third-order neurone.

Abstracts

We investigate neural and behavioral aspects of the interrelation between ‘liking’ and ‘understanding’ when both appraisals are made within one judgment task. Our goal was to explore questions regarding how these appraisals combine, and specifically whether there is an order-effect when both are employed in sequence. To this end, we tested a hypothesis derived from new models in neuroaesthetics, and concerning processing of art, which suggest that perception may involve a natural sequence from first processing for hedonic quality (i.e., liking) followed by processing for understanding. Thus, due to the initial liking assessment's capacity to prime deepened cognitive involvement, a Liking-Understanding order may show key differences in final assessments or brain activation when compared to an Understanding-Liking sequence. Thirty-two participants evaluated a range of paintings, balanced for visual appeal and understandability, in a two-part task in which half evaluated for understanding followed by liking and the other half had question order reversed. Brain activity was recorded via functional Near Infrared Spectroscopy (fNIRS). Results showed no assessment interrelation or order effect in artwork evaluations. However, participants who began with evaluation for liking, and who came to incongruent combinations (i.e., “I like, but I don't understand” or “I don't like, but I understand”), showed significantly higher activation in left medial prefrontal cortex. This area is functionally associated with attention and integration of hedonic/informational elements. Findings provide tentative support for a liking-driven order-effect, as well as for physiological connection between appraisals, which may not appear in behavioral evidence, and suggest need for further consideration of this topic in appraisal research.

Chapter 9 Restoration and deterioration of function by brain grafts in the septohippocampal system

Several features make the septohippocampal system useful, especially for the study of physiological mechanisms of graft-host interactions, such as the hippocampus possesses electrical rhythms, which vary with ongoing behavior in a specific manner, and the excitability changes within the hippocampus are easy to monitor. This chapter discusses the possible mechanisms of electrophysiological recovery in the damaged septohippocampal system following transplantation of solid pieces or suspensions of fetal brain tissue into the lesion cavity or into the hippocampus, and the epileptogenic properties of hippocampal grafts. The experiments, using the septohippocampal model to study the mechanisms of action of brain grafts, suggest that a likely mechanism of restoration of physiological activity of the deafferented hippocampus is a passive bridging action of the graft between the host septum and hippocampus. The chapter demonstrates the reciprocal physiological and anatomical connections between the graft and host, and shows that hippocampal grafts can serve as an implanted epileptic focus, which may further worsen the function of the already damaged brain. However, experiments are required that determine why under certain conditions the grafts produce epileptic activity, while under seemingly similar conditions they lead to the restoration of physiological function of damaged brain circuitries.

Electropuncture therapy trial for treating infertility in mares

Four acupuncture points, BAIHUI, LUANCHOSHU, YANCHI and YOUQUAN were used as electropuncture therapy for infertility in mares; each of these is described. A total of 114 mares on several state breeding stations in Xin-Jiang Uyger Zizhique, China, were checked for infertility by palpation per rectum. Thirteen infertile mares were selected for treatment. As a result of the treatment 12 mares showed normal oestrus and ovulated. The physiological functions and pathological changes of the channels and their collaterals were studied with regard to the mechanism of the theory of acupuncture. This study pays very special attention to the physiological and pathological connection between the internal and external organs and structures.

Synaptic connections between the hindwing stretch receptor and flight motor neurones in the locust revealed by double cobalt labelling for electron microscopy.

Synaptic interactions between sensory and motor neurones in the locust flight system have been investigated by using intracellular labelling with cobalt and nickel for electron microscopy. Simultaneous axonal filling of two neurones with different concentrations of metal ions produces differential labelling, so that contacts between them in the central nervous system can be recognized. We have investigated the connectivity of the hindwing stretch receptor neurone (SR) with a direct hindwing depressor motor neurone (MN 127) known from physiological experiments to receive monosynaptic input from the SR, and an indirect hindwing depressor motor neurone (MN 112/1), for which no monosynaptic connection with the SR has been reported. We have found no direct synapses between the SR and MN 112/1, although some of their branches lie close together in the neuropile. We have, however, found some evidence for polysynaptic connections between them. There are many synapses of conventional dyadic morphology from both the lateral and mediolateral branches of the SR to MN 127; the medial branch was not examined. Those from the lateral branch contact the motor neurone on branches close to the neuropilar segment, while those from the mediolateral branch contact long, thin distal twigs. We estimate that there are about 600 anatomical synapses between these two neurones. Our results suggest that a large number of widely distributed anatomical synapses constitute the physiological synaptic connection between the SR and MN 127. The dyadic arrangement of these synapses provides an anatomical correlate for the physiologically established divergence of SR outputs onto interneurones and motor neurones.

GABAergic agents on the medial septal nucleus affect hippocampal theta rhythm and acetylcholine utilization

Neurons of the medial septal nucleus are important in regulating the physiological activity of the hippocampus. If intraseptal injection of putative neurotransmitter substances affects the turnover rate of hippocampal acetylcholine, then concomitant changes would be expected in the electrophysiologic activity of the hippocampus. A GABA agonist, muscimol, was injected into the medial septum of rats and the effects on hippocampal electrical activity and acetylcholine utilization were studied. The intraseptally injected muscimol (100 ng) resulted in hippocampal electrographic records containing low amplitude asynchronous waves and significantly less rhythmic slow activity (RSA, 6–9 Hz), compared to control injections of saline. This effect was antagonized by prior intraseptal injection of bicuculline (3 μg). The hippocampal electrical activity returned to normal within 100 min. The utilization of acetylcholine was significantly reduced by intraseptal muscimol at times after administration when electrographic activity was also altered, and spontaneous behavioral movement was increased. These results suggest a physiological connection between hippocampal RSA generation and GABAergic mechanisms in the septum.

Wing Hair Plates in Crickets: Physiological Characteristics and Connections with Stridulatory Motor Neurones

ABSTRACT Hairs in the subcostal hair plates of the wings of crickets have a high angular stiffness (5·5 μNmrad−1) when bent about their base. The mean threshold required to elicit action potentials is 15°. Viscous drag from air movements will not deflect the hairs sufficiently to excite them; this will only occur when the hair is bent by the opposite wing. The hair sensillae project to the ventral association area of the mesothoracic ganglion, but the endings of the stridulatory motor neurones are all in dorsal or lateral neuropiles of the thoracic ganglia. Electrical stimulation of the hair plates evokes reliable EPSPs in opener (M99), closer (M90) and wing folding (M85) motor neurones, after latencies of 4–20 ms, depending on the neurone. Properties of the hairs and motor neurones suggest that these EPSPs in the wing folding muscle (M85) and closer (M90) could play an important role in the control of wing position seen in recent behavioural study.

In vitro metabolism of cadaverine in the pregnant rat.

The in vitro metabolism of 14C-cadaverine by diamine oxidase was investigated in various tissues of pregnant and non-pregnant rats. The metabolites formed were: delta 1-piperideine, delta-aminovaleric acid, carbon dioxide and some unidentified compound(s). In most of the tissues investigated delta 1-piperideine was the predominant metabolite, but considerable amounts of delta-aminovaleric acid and the unidentified compound(s) were also formed. The oxidative products of cadaverine might be of importance in various physiological and pathophysiological connections associated with elevated diamine oxidase levels.

A temporal analysis for mother-infant relationships in a group of Non-human Primates

Summary Infants belonging to a group of macaques (Macaca mulatta) kept in semicaptivity were maintained under observation, as the focus animal, for a 90-day-period at the California Primate Research Center, Davis. The observations made according to an ethological method (use of stop-watch and check-sheets) aimed at studying the ontogenetic development of some motherinfant interactions during the first phase of the growing up of the infants (the youngest, 3 months old; the oldest, 5 months). More precisely, we analysed 5 different types of temporal sequences, or rather interval times, dating from the beginning of the following mother-infant behaviours: On mother, Nipple, Immobile, and G.b.m.d. On (Grooming by mother during On). From all the possible sequences that we were able to obtain by combining the behaviour patterns two by two, we decided to select only the following rational dyads: B: On mother-B. Immobile, B. Immobile -B. G.b.m.d. On, B. On mother-B. Nipple, B. Nipple, B. Immobile, B. On mother - B. G.b.m.d. On (B = beginning). The longitudinal analysis of the data was executed by using linear trend analysis (i.e. Y = a + bX). Results showed that the interval time related to the feeding time remained constant throughout the three months of observation. The interval time: B. On mother -B. Nipple had a very low coefficient of regression (b = -.26 for the males and b = -.19 for the females). A similar result emerged for the interval time: B. On mother -B. G.b.m.d. On (b = -1.45 for the males and b = - 1.6 for the females). This shows that in most cases the interval times were not distributed chaotically but were sufficiently regular: the slope related to the interval B. On mother -B. Nipple is nearly parallel to the abscissa. This could demonstrate that the interval times concerning mother-infant relationships could be conditioned by feeding (Nipple) and also by G.b.m.d. On. The last two behaviour patterns could determine the type of relation between the partners although the infant receives the greater benefits. Although we did not speak about the physiological connections between Nipple and suckling, it is obvious that this last could occur only simultaneously with Nipple. This work was an attempt to individuate the trends of some temporal variables related to the mother-infant relationship and to maternal care behaviour and those elements which could condition these trends. The slope related to the interval between the moment in which the infant enters into contact with his mother (On mother) and after he has taken the mother's nipple into his mouth is in fact more significative. This last fact induces us to believe that these interactions during this kind of morther-infant relationship are hereditarily coordinated, especially during this early phase of the infant's development.

Embryonic brain extract induces collagen biosynthesis in cultured muscle cells: involvement in acetylcholine receptor aggregation.

The involvement of extracellular matrix components in induction of the aggregation of acetylcholine (AcCho) receptors by factor(s) present in embryonic brain extract was investigated. Embryonic brain extract induced a three-fold increase in the number of AcCho receptor aggregates on the surface of cultured myotubes and a 5- to 10-fold increase in the synthesis of procollagen, which was secreted into the medium and converted to collagen. Adult brain extract, embryonic serum, and embryonic liver extract were less active in stimulating both collagen synthesis and AcCho receptor aggregation. A physiological connection between the two processes is suggested, since the number of AcCho receptor aggregates could be reduced to control levels by treating brain extract-stimulated myotubes with purified bacterial collagenase. In addition, stimulation of collagen secretion by ascorbic acid (50 micrograms/ml) promoted a 1.6-fold increase in AcCho receptor aggregation. When ascorbic acid was added together with the brain extract, further increases in both collagen synthesis and AcCho receptor aggregation were observed.

Evidence that the gamma-glutamyl cycle functions in vivo using intracellular glutathione: effects of amino acids and selective inhibition of enzymes.

The function of the gamma-glutamyl cycle was explored in in vivo studies in which amino acids and specific inhibitors of cycle enzymes (gamma-glutamyl transpeptidase, gamma-glutamyl cyclotransferase, gamma-glutamylcysteine synthetase, and 5-oxoprolinase) were administered to mice. The findings, which show that the gamma-glutamyl cycle functions in vivo, support the conclusion that gamma-glutamyl amino acids formed by gamma-glutamyl transpeptidase from externally supplied amino acids and intracellular glutathione are translocated into the cell and thus indicate that there is a significant physiological connection between the metabolism of glutathione and the transport of amino acids.

A new pattern of morphofunctional relationship among cranial nerves: Evidence of anatomical and physiological connection between trigeminus and oculomotor nerves

It is shown that the cell bodies of the afferent fibres supplying the proprioceptivity to the extrinsic eye muscles are located within the semilunar ganglion. Furthermore, some Gasserian cells have central processes which enter the midbrain through the oculomotor nerve. Sensory ganglion cells, derived from the same strand of placodal cells forming the ophthalmic lobe, can be constantly detected within the oculomotor nerve of ox, monkey and man.