Nerve Impulse Patterns And Reflex Control in the Motor System of The Crayfish Claw

1965 ◽  
Vol 43 (2) ◽  
pp. 193-210
Author(s):  
D. M. WILSON ◽  
W. J. DAVIS
Keyword(s):  
Motor Neurons ◽  
Nerve Impulse ◽  
Apparent Lack ◽  
High Frequencies ◽  
Excitatory State ◽  
Input Source ◽  
Motor Neuron Pool ◽  
Frequency Changes ◽  
Positive Correlations ◽  
Interval Lengths

1. The opener muscle of the crayfish claw receives, under nearly natural conditions, a train of excitatory nerve impulses which may show a temporal patterning to which the muscle is specially sensitive. Especially at high frequencies the impulse train contains doublets which form a separate class in the interval distribution. Their appearance at high frequencies gives rise to an increase in the coefficient of variation of interval lengths. 2. Excitatory and inhibitory motor neurons to the same opener muscle seem to be part of the same commonly excited motor neuron pool. Frequency changes in the two axons generally show positive correlations. For most inputs and for ‘spontaneous’ central drive the excitor has the lowest threshold and shortest latency, and it gives the earliest indication of changes of excitatory state. 3. Proprioceptive input from the claw may excite both motor neurons, but generally the inhibitory one gives the earlier, bigger response. The peripheral inhibition completes a negative feedback loop. 4. Inhibitory frequencies plotted against concurrent excitatory frequencies give points falling into two groups with different slopes dependent upon input source. For general body inputs the slope is less than one and for proprioceptive claw input it is much more than one. This divergence leads to greater effectiveness of either excitation or inhibition as overall level of output increases, with a good separation of antagonistic functions in spite of the apparent lack of reciprocal interaction.

Development of leaps in dusky dolphin (Lagenorhynchus obscurus) calves

Behaviour ◽  
2014 ◽  
Vol 151 (11) ◽  
pp. 1555-1577 ◽  
Author(s):  
Sierra Deutsch ◽  
Heidi Pearson ◽  
Bernd Würsig
Keyword(s):  
Adaptive Significance ◽  
Behavioral State ◽  
Lagenorhynchus Obscurus ◽  
Frequency Changes ◽  
Positive Correlations ◽  
Dusky Dolphins ◽  
Dusky Dolphin ◽  
The Relationship ◽  
Early Late ◽  
Age Category

Leaping is a highly conspicuous behavior in cetaceans that may function in cooperative hunting and social bonding, thereby converging with forms of intra-specific communication present in other social mammals. However, few studies have analyzed the ontogeny of leaping, an important aspect in determining the adaptive significance of this behavior. The objective of our study was to quantify the ontogeny of leaping in dusky dolphins, a highly acrobatic species that engages in a variety of aerial displays. We tested the hypotheses that: (1) leap frequency changes with calf age, (2) frequency of leap type varies with calf age and (3) frequency of leap type varies by behavioral state. Data were collected off Kaikoura, New Zealand through boat-based group focal follows of nursery groups from October 2006–May 2007. We analyzed data from 73 nursery group encounters according to age category (young calf, yearling) and season (early, late). Early young calves leapt less frequently than late young calves (), but leap frequency did not appear to differ among older calves. Calves learned noisy leaps first, followed by clean leaps, then coordinated leaps, and finally acrobatic leaps as indicated by the positive correlations between week (i.e., calf age) and frequency of clean (), acrobatic () and coordinated () leaps. The relationship between behavioral state and frequency of leap type was not significant. These results indicate that nursery groups represent an important environment for healthy physical and social development of calves. Furthermore, while calves appear to learn the mechanics of leaping individually, they appear to learn the context in which the leaps are performed from conspecifics. This indicates that, as for other socially-complex mammals such as other cetaceans, primates, and social carnivores, social learning may be an important component in the ontogeny of dusky dolphin behavior.

scholarly journals Coat colour in mouse populations selected for weight gain: support for hitchhiking, not pleiotropy

2013 ◽  
Vol 95 (1) ◽  
pp. 4-13 ◽  
Author(s):  
PHILIP W. HEDRICK
Keyword(s):  
Weight Gain ◽  
Allele Frequency ◽  
High Weight ◽  
Coat Colour ◽  
Correlated Response ◽  
Term Selection ◽  
Low Weight ◽  
High Weight Gain ◽  
Frequency Changes ◽  
Positive Correlations

SummaryWith many molecular markers in many species, research efforts in quantitative genetics have focused on dissecting these traits and understanding the importance of factors such as correlated response due to hitchhiking or pleiotropy. Here, in an examination of long-term selection experiments in mice, the evidence strongly supports the primary importance of hitchhiking on the coat colour loci brown and dilute in mice selected for high weight gain. First, the amount of observed change in coat colour allele frequency could not be explained by genetic drift alone, implying that selection was of high importance. Second, the allele frequency changes included reversals in the direction change, but there were still positive correlations in the early generations with differences in weight gain between the phenotypes. Third, the correlation between the change in allele frequencies and phenotypic difference in weight gain declined over time, consistent with the decay expected from linkage associations. Fourth, the changes at both loci in a short-term selection experiment for low weight gain were in the opposite direction than the changes in the contemporaneous related population selected for high weight gain.

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

Ultrastructure of Fibroblast Cultures, Lymphocytes, and Liver in Mucopolysaccharidoses Types I, II, III, IV, and VI.

1970 ◽  
Vol 28 ◽  
pp. 204-205
Author(s):  
George Hug ◽  
William K. Schubert ◽  
Shirley Soukup
Keyword(s):  
Lysosomal Enzyme ◽  
Apparent Lack ◽  
Fibroblast Cultures ◽  
Lysosomal Diseases ◽  
Disease Specificity ◽  
Deficient Activity

McKusick subdivided the syndrome of mucopolysaccharidoses into six types according to clinical, roentenographic, and genetic criteria and to the kind of mucopolysaccharide(s) excreted in the urine (1). Deficient activity of a lysosomal enzyme, (β-galactosidase, has recently been reported in types I, II and III of mucopolysaccharidoses as well as in generalized gangliosidosis (2). This apparent lack of disease specificity makes the enzymatic deficiency difficult to interpret. Nevertheless, the involvement of a lysosomal enzyme tends to characterize these disorders as lysosomal diseases.

XRF and PIXE Analysis of light and Dark Adapted Ocular Tissue

1982 ◽  
Vol 40 ◽  
pp. 190-191
Author(s):  
B. J. Panessa ◽  
H. W. Kraner ◽  
J. B. Warren ◽  
K. W. Jones
Keyword(s):  
Trace Metals ◽  
Pigment Epithelium ◽  
Nerve Impulse ◽  
Light Response ◽  
Ocular Tissue ◽  
Emission Spectrometry ◽  
Retinol Dehydrogenase ◽  
Pixe Analysis ◽  
X Ray ◽  
Optimal Function

During photoexcitation the retina requires specific electrolytes and trace metals for optimal function (Na, Mg, Cl, K, Ca, S, P, Cu and Zn). According to Hagins (1981), photoexcitation and generation of a nerve impulse involves the movement of Ca from the rhodopsin-ladened membranes of the rod outer segment (ROS) to the plasmalemma, which in turn decreases the in-flow of Na into the photoreceptor, resulting in hyperpolarization. In toad isolated retinas, the presence of Ba has been found to increase the amplitude and prolong the delay of the light response (Brown and Flaming, 1978). Trace metals such as Cu, Zn and Se are essential for the activity of the metalloenzymes of the retina and retina pigment epithelium (RPE) (i.e. carbonic anhydrase, retinol dehydrogenase, tyrosinase, glutathione peroxidase, superoxide dismutase...). Therefore the content and fluctuations of these elements in the retina and choroid are of fundamental importance for the maintenance of vision. This paper presents elemental data from light and dark adapted frog ocular tissues examined by electron beam induced x-ray microanalysis, x-ray fluorescence spectrometry (XRF) and proton induced x-ray emission spectrometry (PIXE).

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

A Test of Three Sadism Measures

2020 ◽  
Vol 41 (4) ◽  
pp. 219-227 ◽  
Author(s):  
Bojana M. Dinić ◽  
Tara Bulut Allred ◽  
Boban Petrović ◽  
Anja Wertag
Keyword(s):  
Item Response ◽  
Social Groups ◽  
Similarity Index ◽  
Dark Triad ◽  
Hierarchical Regression ◽  
Fit Indices ◽  
Profile Similarity ◽  
Positive Attitudes ◽  
Confirmatory Factor ◽  
Positive Correlations

Abstract. The aim of this study was to evaluate psychometric properties of three sadism scales: Short Sadistic Impulse Scale (SSIS), Varieties of Sadistic Tendencies (VAST, which measures direct and vicarious sadism), and Assessment of Sadistic Personality (ASP). Sample included 443 participants (50.1% men) from the general population. Reliability based on internal consistency of all scales was good, and results of Confirmatory Factor Analysis (CFA) showed that all three scales had acceptable fit indices for the proposed structure. Results of Item Response Theory (IRT) analysis showed that all three scales had higher measurement precision (information) in above-average scores. Validity of the scales was supported through moderate to high positive correlations with the Dark Triad traits, especially psychopathy, as well as positive correlations with aggressiveness and negative with Honesty-Humility. Moreover, results of hierarchical regression analysis showed that all three measures of direct, but not vicarious sadism, contributed significantly above and beyond other Dark Triad traits to the prediction of increased positive attitudes toward dangerous social groups. The profile similarity index showed that the SSIS and the ASP were highly overlapping, while vicarious sadism seems distinct from other sadism scales.

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