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  • 1
    ISSN: 1432-1106
    Keywords: Preoptic unit activity ; Stimulation of mesencephalon ; Amygdala ; Mediobasal hypothalamus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single cell activity from preoptic neurons was extracellularly recorded in normal female rats and the effects of electrical stimulation of the mediocortical amygdala (AMY), the N. med. raphes (MES) and the mediobasal hypothalamus (MBH) was tested. 1. One type of preoptic neurons (55%) reacted with primary excitation to a single electrical stimulus of AMY, MES or MBH, which was usually followed by a period of postexcitatory inhibition. Another type of neurons (29%) were first inhibited after stimulation of AMY, MES or MBH and then showed a period of postinhibitory excitation. The discharge rate of a third type was not affected by electrical stimulation of these structures (16%). If a neuron was affected by a stimulus in a given area it predictably reacted in the same fashion to stimulation of the other areas. 2. The postexcitatory inhibition of the majority of the primarily excited neurons was strong enough to prevent the stimulus response to a second stimulus. Occasional recordings from two neighboured cells simultaneously indicate that they can be inhibitory to each other. 3. By pulse train stimulation of the AMY or MES with varying frequencies it could be demonstrated that low frequencies (10 Hz) had a facilitatory action whereas higher frequencies (100 Hz) were inhibitory to preoptic discharge rates. 4. No obvious alteration of neuronal properties we found neither in rats treated intraventricularly with 5,6-dihydroxytryptamine, which strongly reduces central nervous system serotonin content, nor in 6-hydroxydopamine treated rats, which had low central nervous system catecholamine levels.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 43 (1981), S. 1-10 
    ISSN: 1432-1106
    Keywords: Olfactory bulb ; Amygdala ; Mediobasal hypothalamus ; Electrophysiology ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To analyse fibre connections between the olfactory bulb (OB) and limbic-hypothalamic structures, the lateral olfactory tract (LOT) was stimulated electrically and extracellular action potentials were recorded from single units in the OB, the cortico-medial portion of the amygdala (AMY) and the mediobasal hypothalamus (MBH). More than 29% of the antidromically identified mitral cells in the OB showed a spontaneous episodic firing pattern consisting of alternating periods of activity and inactivity. Nearly 14% of the orthodromically excited non-mitral cells showed the same phasic firing pattern. 2.9% of AMY neurons were antidromically activated by LOT stimulation, whereas more than 52% showed orthodromic responses. In contrast to the AMY no neuron in the MBH could be antidromically invaded by electrical stimulation. The incidence of orthodromic responses was much less in the MBH when compared to the AMY (13.5%). It is concluded that the firing pattern of OB cells in the pig is complex, often phasic and unrelated to respiration or sniffing. The main OB is more closely related to the AMY than to the MBH. It is suggested that olfactory information is probably transmitted to the MBH via the AMY. The AMY may play a role in the regulation of OB activity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 69 (1987), S. 208-212 
    ISSN: 1432-1106
    Keywords: Prenatal development ; Messenger RNA ; Brain ; Opioids ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using solution hybridization analysis and Northern blotting with complementary RNA probes labelled to high specific activity, levels of proenkephalin A and B mRNA were analyzed throughout prenatal development in the hippocampus and striatum of fetal pigs. A differential time course for the appearance of these opioid precursor mRNAs was observed: in hippocampus, both mRNAs increased linearly throughout development with proenkephalin B mRNA increasing faster than proenkephalin A mRNA. In striatum, both mRNAs behaved similarly, increasing to a maximum level around mid-gestation and declining thereafter. The differences might be attributed to differential localization of the two precursor systems in the tissues and might be of functional relevance.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 43 (1981), S. 107-110 
    ISSN: 1432-1106
    Keywords: Suckling ; Pig ; Milk ejection ; Sleep ; EEG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electroencephalographic and electromyographic activities were recorded together with variations in intramammary pressure in unanaesthetized lactating sows during suckling. During each suckling period, milk ejection resulted in a sudden and brief rise in intramammary pressure. From the onset of suckling to the beginning of milk ejection, polygraphic recordings as well as observations of behaviour revealed that the sow was invariably in a state of arousal. This suggests that, unlike what has been proposed for the rat, sleep is not a necessary component of the milk ejection reflex in the pig.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Antidromic activation ; Latency variation ; Axonal excitability ; Paraventricular nucleus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Magnocellular neurosecretory cells were antidromically identified in the hypothalamic paraventricular nucleus (PVN) of urethane-anesthetized, ovariectomized female rats following electrical stimulation of the neurohypophysis. Seventy-one cells with a tonic pattern of spontaneous discharge were distinguished and used to examine the relationships between the measures of antidromic spike latency, activation threshold and discharge rate. The discharge rate was artificially modulated by either microiontophoresis of glutamate or antidromic stimulation of the neurohypophysis. In all the PVN cells with tonic activity, the latency lengthened and the threshold increased as a function of the discharge rate. Activation of individual cells by microiontophoresis of glutamate was effective, as was simultaneous activation of many PVN cells by antidromic stimulus. Similar relationships between the discharge rate and the parameters of antidromic activation were seen in 3 cells, when their rates varied spontaneously over a wide range without manipulation. These data suggest that the excitability of axons of presumed oxytocinergic cells in the PVN-neurohypophyseal system are influenced by their prior activity, probably through metabolic changes in individual axons.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 62 (1986), S. 635-641 
    ISSN: 1432-1106
    Keywords: Embryonal development ; Paraventricular nucleus ; Action potential ; Chicken embryo ; Electrophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For the full understanding of the ontogeny of the electrical activity in the brain it is essential to record single unit activity of the fetus. However, investigations of the functional development of neuronal properties in mammals are largely limited by the inaccessability of the prenatal brain. Therefore, we have designed a new method to record extracellular single unit activities of identified magnocellular neurones in the Nucleus paraventricularis of the chicken embryo after 18 days of incubation. One hundred and four magnocellular neurones were identified by antidromic stimulation from the neural lobe. In a high percentage of the neurones an A-B inflexion of the action potential could be observed similar to that frequently encountered in mammalian magnocellular neurones. The mean duration of the action potential was 2.8 ms with a range between less than 1 ms and 7 ms. This large range is probably due to developmental processes of the cell membrane and subsequent changes in the extra- und intracellular ion concentration. Fourty-six percent of the neurones generated spontaneous action potentials with a slow irregular firing pattern. The mean discharge frequency was estimated as approx. 1 Hz. In further 13% of the cells orthodromic action potentials could be observed only after the occurrence of several antidromic spikes. The data presented are the first recordings of single unit activity in the magnocellular system in the prenatal brain. They demonstrate that the chicken embryo may offer a suitable model to study the ontogeny of neuroendocrine systems in the fetal brain in-vivo.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 62 (1986), S. 642-647 
    ISSN: 1432-1106
    Keywords: Ontogeny ; Paraventricular nucleus ; Hypothalamo-neurohypophysial system ; Electrophysiology ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present paper investigates the ontogeny of connective patterns in the brain of the 17-, 17.5-, and 18-day-old chicken embryo and in the newborn chicken as well. From the onset of electrical activity, neurophysiological properties of neurones undergo significant changes during further development. Total duration of action potentials decreases (p 〈 0.001) between day 17 of incubation and day one of life. The percentage of spontaneously active neurones increases significantly (p 〈 0.01) from 20% on day 17 to 69% in the newborn chick. For the same time period mean conduction velocity of presumed non-mylinated fibers in the hypothalamo-neurohypophysial-tract increases by about 50%. On the other hand, mean constant latency decreases from 20 ms in the 17-day-old embryo to 15.5ms in the newborn chick (p 〈 0.001). Changes in threshold intensity to antidromic stimulation and the increasing number of identifiable neurones per embryo indicate that new cell populations may become excitable during development. The results show, that considerable maturational events take place in action potential properties of the magnocellular system during late embryonal and early postnatal life of the chicken.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Animal Reproduction Science 11 (1986), S. 243-248 
    ISSN: 0378-4320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0378-4320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Animal Reproduction Science 11 (1986), S. 195-205 
    ISSN: 0378-4320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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