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91.
Connections between descending visual interneurons and metathoracic motoneurons in the locust 总被引:1,自引:1,他引:0
M. Burrows Dr. C. H. Fraser Rowell 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1973,85(3):221-234
Summary Connections between the four DMD neurons and metathoracic motoneurons in the locustSchistocerca were examined by recording extracellularly from the interneurons in the pro-mesothoracic connectives and intracellularly
from seventeen motoneurons. A DIMD or DCMD spike causes an EPSP in the fast extensor tibiae motoneuron, which can be modified
by changing the membrane potential. The EPSP always follows spikes at frequencies up to 200 Hz and with a latency of 0.9 ms,
suggesting that the connections are monosynaptic and chemically mediated. EPSPs from the DIMD or DCMD arrive at the same time,
their axons having the same conduction velocity, and appear simultaneously in the fast extensor tibiae motoneurons on both
sides of the ganglion. There is spatial and temporal summation between the inputs but on no occasion did the motoneurons spike.
Three inhibitory neurons are depolarized by DMD inputs and may on occasion spike, but it is not known whether these connections
are direct. Similarly the slow excitatory motoneuron to the anterior coxal adductor muscle is hyperpolarized by DMD input.
Other leg, flight or ventilatory motoneurons examined received no inputs from the DMD neurons. The connections shown are consistent
with the hypothesis that the DMD neurons are in some way involved with initiation of a jump, but to achieve this must act
synergistically with other inputs.
This work was supported in part by USPHS grant No. NS 09404-03 to C.H.F.R. Dr. Rowell wishes to thank Dr. J. Phillipson for
the use of facilities in the Oxford Department of Zoology during sabbatical leave. 相似文献
92.
Abstract: The mesolimbic system of the brain has been shown to be involved in the reward properties of a number of agents. It is possible that release of monoamines by nicotine in this brain area could be related to the pleasurable aspects related to cigarette smoking. In this investigation, the effect of nicotine on the release of [3 H]dopamine in the nucleus accumbens of the rat was studied. It was shown that nicotine produced a concentration-dependent increase in [3 H]dopamine release at concentrations of 0.1 μ M and above. The increase in release was found to be almost completely calcium dependent. The nicotine-induced release was only partially blocked by the nicotinic antagonists hexamethonium and d -tubocurarine. A number of cholinergic agonists, as well as other compounds, were tested for their capacity to mimic the effect of nicotine. At equimolar concentrations there was, at most, only 50% of the activity of nicotine. The results of this study demonstrate that nicotine stimulates the release of dopamine in the nucleus accumbens at concentrations similar to those in the blood of cigarette smokers. This suggests that the release of mono-amines in specific nuclei of the mesolimbic system may be an important determinant of the desire to smoke cigarettes. 相似文献
93.
Choline and phosphatidylcholine tissue concentrations were examined in mice treated with long-term (18–22 month) dietary choline enrichment, choline deficiency, or phosphatidylcholine enrichment. There were no significant differences found in choline levels among the dietary groups in any of the tissues examined: plasma, erythrocytes, cortex, hippocampus, and striatum. In contrast, the concentration of phosphatidylcholine in both the choline enriched and phosphatidylcholine enriched groups were significantly increased in the cortex, compared to the choline deficient group, and in the striatum, compared to control. No differences in phosphatidylcholine concentration were found in the hippocampus or plasma between any of the dietary groups. These results are in contrast to the reported effects of acute or short-term choline and phosphatidylcholine treatment and indicate that there may be differences between the effects of short-term and long-term administration on the blood and brain levels of choline and phosphatidylcholine. 相似文献
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Data from a 2-year field study of patas monkeys (Erythrocebus patas) in Kenya support our earlier suggestion that diurnal
births are a species-typical pattern of patas. In this respect patas are very unusual, as all existing information shows that
nocturnal births are typical of both captive and freeranging monkeys. Patas do not give birth at night because to do so would
render ineffective their night-resting strategy which reduces vulnerability to predation at night. Giving birth during the
day, however, does not eliminate the risk of being preyed on; nor are all times of day equally favorable for giving birth.
Our field data suggest that a patas female gives birth at those times of day when she is least likely to lose contact with
her group or to encounter predators. 相似文献
97.
Neville Rowell 《BMJ (Clinical research ed.)》1961,1(5240):1687-1688
98.
Friedrich Bergann Martin Borrill Elmo W. Davis M. Demerec Earl R. Leng L. F. Bauman C. C. Moh R. A. Nilan F. C. Elliott J. B. Rowell F. Schwanitz H. Schwanitz F. Laibach H. F. Linkens James L. Liverman Mary P. Johnson Lawrence Starr Günther Steyer S. J. Wellensiek F. A. Hakkaart 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1956,26(4-5):158-160
Ohne Zusammenfassung 相似文献
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