The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Franklin B. Krasne - One of the best experts on this subject based on the ideXlab platform.
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Altered Excitability of the Crayfish Lateral Giant Escape Reflex during Agonistic Encounters
2015Co-Authors: Franklin B. Krasne, Ashkan Shamsian, Raghavendra KulkarniAbstract:The excitability of the lateral giant Escape Reflex of socially dominant and submissive crayfish at rest and during agonistic encounters was studied and compared. During agonistic en-counters the excitability of the lateral giant Reflex falls, substan-tially in subordinates and slightly in dominants, whereas at rest excitability seems to be independent of social status. Thus, paradoxically, socially dominant animals are more likely to execute lateral giant Escape reactions during interactions than are subordinates. It is suggested that subordinates under threat of attack tend to engage circuitry involved in flexible, nonReflex (“voluntary”) types of Escape not mediated by giant neurons and therefore inhibit giant neuron-mediated Reflex circuitry that produces prompt, but less adaptive, responses. In contrast, dominants go about their business, mainly ignoring their con-specifics and relying on Reflex Escape to protect them fro
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Rostral ganglia are required for induction but not expression of crayfish Escape Reflex habituation: role of higher centers in reprogramming low-level circuits.
Journal of neurophysiology, 2005Co-Authors: David Shirinyan, Terri M. Teshiba, Karen Taylor, Pia O'neill, Sunhee Cho Lee, Franklin B. KrasneAbstract:It is widely assumed that learning results from alterations in the strength of synapses within the neural pathways that mediate a learned behavioral response and that these alterations are directly caused by training-induced activity of neurons connected by the changing synapses. Initial evidence for this view came from studies of habituation of defensive Reflexes in several invertebrate species. However, more recent studies of habituation of the Escape Reflex in one of these species, the crayfish, have shown that habituation is substantially caused by tonic inhibitory input from cephalic ganglia; this descending inhibition suppresses the activity of neurons within the Escape circuit, which reside in caudal ganglia. Such control by descending inhibition indicates that animals with encephalized nervous systems do not entirely abdicate to low-level circuitry the important decision of whether to habituate to stimuli that might warn of danger. Higher centers in fact play a major role in controlling the habituation of this potentially life-saving protective response. Another way for higher centers to control lower ones would be to induce alteration of the lower center's intrinsic properties. Here, we show that, whereas descending input from higher ganglia is needed to induce habituation, once established, habituation persists even after rostral ganglia are disconnected. This provides evidence that lower-level neural circuits can be reprogrammed through transient interaction with higher ganglia to decrease their intrinsic tendency to produce Escape.
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Modulation of the crayfish Escape Reflex--physiology and neuroethology
Integrative and comparative biology, 2002Co-Authors: Franklin B. Krasne, Donald H. EdwardsAbstract:SYNOPSIS. We review here factors that control the excitability of the giant neuron-mediated tail-flip Escape behavior in crayfish, focusing especially on recent findings concerning serotonergic modulation. Serotonin can either facilitate or inhibit Escape depending on concentration and pattern of application. Low concentrations facilitate while high ones inhibit; however, if high concentrations arise gradually they facilitate instead of inhibiting. The effects of serotonin can also be altered by social experience, with application regimens that cause facilitation in social isolates coming to produce inhibition after an extended period of living as a subordinate. Attempts to understand both the possible physiological basis of some of these complexities and their possible function are discussed. Neuroethological investigations indicate that giant neuronmediated Escape is inhibited during the initial fights that establish social relationships and is facilitated in their immediate aftermath. Once the relationship of a pair is well-established, the presence of the dominant tends to suppress giant neuron-mediated Escape (but not tail-flip Escape mediated by non-giant circuitry) in the subordinate, but the presence of the subordinate has relatively little effect on the dominant. These patterns of modulation can be seen as consistent with the known variations in serotonin’s effect as a function of concentration and social experience and may provide a biological reason for these variations. For most neurobiologists it is an article of faith that the behavior which emerges from nervous systems is the product of a neural machine. But the machine is one in which a given neural circuit does not always work the same way. Operational properties of a circuit can change due to learning and due to modulation by other circuits, imparting to the behavior of a given individual the great variety and irregularity that makes the behavior of animals and ourselves interesting and a challenge to our understanding. To a great degree, though not entirely, changes in the properties of neural circuits are due to changes in the functional properties of their synapses. The last several decades have seen remarkable pro
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Altered Excitability of the Crayfish Lateral Giant Escape Reflex during Agonistic Encounters
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1997Co-Authors: Franklin B. Krasne, Ashkan Shamsian, Raghavendra KulkarniAbstract:The excitability of the lateral giant Escape Reflex of socially dominant and submissive crayfish at rest and during agonistic encounters was studied and compared. During agonistic encounters the excitability of the lateral giant Reflex falls, substantially in subordinates and slightly in dominants, whereas at rest excitability seems to be independent of social status. Thus, paradoxically, socially dominant animals are more likely to execute lateral giant Escape reactions during interactions than are subordinates. It is suggested that subordinates under threat of attack tend to engage circuitry involved in flexible, nonReflex (“voluntary”) types of Escape not mediated by giant neurons and therefore inhibit giant neuron-mediated Reflex circuitry that produces prompt, but less adaptive, responses. In contrast, dominants go about their business, mainly ignoring their conspecifics and relying on Reflex Escape to protect them from unexpected attack. Consistent with this view, Escape of subordinates during agonistic encounters is mediated by nongiant, not Reflex, circuitry. These observations and their interpretation suggest a possible functional role for recently described social status-dependent serotonergic modulation of the lateral giant Reflex, which is inhibitory in sign in subordinates and facilitatory in dominants.
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Habituation of an invertebrate Escape Reflex due to modulation by higher centers rather than local events.
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Franklin B. Krasne, Terri M. TeshibaAbstract:Learning is widely thought to result from altered potency of synapses within the neural pathways that mediate the learned behavior. Support for this belief, which pervades current physiological and computational thinking, comes especially from the analysis of cases of simple learning in invertebrates. Here, evidence is presented that in one such case, habituation of crayfish Escape, the learning is more due to onset of tonic descending inhibition than to the intrinsic depression of circuit synapses to which it was previously attributed. Thus, the altered performance seems to depend at least as much on events in higher centers as on local plasticity.
Terri M. Teshiba - One of the best experts on this subject based on the ideXlab platform.
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Rostral ganglia are required for induction but not expression of crayfish Escape Reflex habituation: role of higher centers in reprogramming low-level circuits.
Journal of neurophysiology, 2005Co-Authors: David Shirinyan, Terri M. Teshiba, Karen Taylor, Pia O'neill, Sunhee Cho Lee, Franklin B. KrasneAbstract:It is widely assumed that learning results from alterations in the strength of synapses within the neural pathways that mediate a learned behavioral response and that these alterations are directly caused by training-induced activity of neurons connected by the changing synapses. Initial evidence for this view came from studies of habituation of defensive Reflexes in several invertebrate species. However, more recent studies of habituation of the Escape Reflex in one of these species, the crayfish, have shown that habituation is substantially caused by tonic inhibitory input from cephalic ganglia; this descending inhibition suppresses the activity of neurons within the Escape circuit, which reside in caudal ganglia. Such control by descending inhibition indicates that animals with encephalized nervous systems do not entirely abdicate to low-level circuitry the important decision of whether to habituate to stimuli that might warn of danger. Higher centers in fact play a major role in controlling the habituation of this potentially life-saving protective response. Another way for higher centers to control lower ones would be to induce alteration of the lower center's intrinsic properties. Here, we show that, whereas descending input from higher ganglia is needed to induce habituation, once established, habituation persists even after rostral ganglia are disconnected. This provides evidence that lower-level neural circuits can be reprogrammed through transient interaction with higher ganglia to decrease their intrinsic tendency to produce Escape.
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Habituation of an invertebrate Escape Reflex due to modulation by higher centers rather than local events.
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Franklin B. Krasne, Terri M. TeshibaAbstract:Learning is widely thought to result from altered potency of synapses within the neural pathways that mediate the learned behavior. Support for this belief, which pervades current physiological and computational thinking, comes especially from the analysis of cases of simple learning in invertebrates. Here, evidence is presented that in one such case, habituation of crayfish Escape, the learning is more due to onset of tonic descending inhibition than to the intrinsic depression of circuit synapses to which it was previously attributed. Thus, the altered performance seems to depend at least as much on events in higher centers as on local plasticity.
Peter Perman - One of the best experts on this subject based on the ideXlab platform.
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New Mycotic Infection Associated with Mortalities in Small Mouthed Salamander (Ambystoma texanum)
2014Co-Authors: Ehab Elsayed, Leonel Mendoza, Yu Man Lee, Mohamed Faisal, Peter PermanAbstract:Abstract: The recent global decline in amphibian population is a mysterious environmental puzzle. While some declines are undoubtedly because of habitat obliteration, others are clearly linked to diseases. Two emerging diseases are blamed to the increasing reports of mortalities among wild amphibians, Chytridiomycosis and Ranavirus infection. Since first report of both diseases during the last decades, there have been an increasing number of observations of the two diseases in amphibian populations, due partly the increased worldwide interest in amphibians as indicators of declining ecosystem health. Nonetheless, the decline due to mortalities associated with additional and as yet unreported pathogens of amphibian have not been considered. Here, we report a new cutaneous Zygomycosis infection caused by Mucor sp. associated with mortalities in an endangered salamander species in Michigan. The infection was observed in terrestrial individuals at the start of the breeding season. Affected salamanders showed sluggish Escape Reflex which allowed easily catching of the infected individuals. Clinical examination revealed scaly and nodular appearance of the skin of the posterior half, especially in the tail region. Mycotic examination resulted in isolation Mucor sp from deep layer of the epidermis of at the affected site. Histopathological examination is currently performed to detect the pathological changes associated with fungu
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New Mycotic Infection Associated with Mortalities in Small Mouthed Salamander (Ambystoma texanum)
2006Co-Authors: Ehab E. El-sayed, Leonel Mendoza, Yu Man Lee, Mohamed Faisal, Peter PermanAbstract:The recent global decline in amphibian population is a mysterious environmental puzzle. While some declines are undoubtedly because of habitat obliteration, others are clearly linked to diseases. Two emerging diseases are blamed to the increasing reports of mortalities among wild amphibians, Chytridiomycosis and Ranavirus infection. Since first report of both diseases during the last decades, there have been an increasing number of observations of the two diseases in amphibian populations, due partly the increased worldwide interest in amphibians as indicators of declining ecosystem health. Nonetheless, the decline due to mortalities associated with additional and as yet unreported pathogens of amphibian have not been considered. Here, we report a new cutaneous Zygomycosis infection caused by Mucor sp. associated with mortalities in an endangered salamander species in Michigan. The infection was observed in terrestrial individuals at the start of the breeding season. Affected salamanders showed sluggish Escape Reflex which allowed easily catching of the infected individuals. Clinical examination revealed scaly and nodular appearance of the skin of the posterior half, especially in the tail region. Mycotic examination resulted in isolation Mucor sp from deep layer of the epidermis of at the affected site. Histopathological examination is currently performed to detect the pathological changes associated with fungus infection. This is considered the first report of zygomycosis in a salamander in the world. (The Journal of American Science. 2006;2(3):19-22).
Kenneth J. Muller - One of the best experts on this subject based on the ideXlab platform.
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Progressive recovery of learning during regeneration of a single synapse in the medicinal leech.
The Journal of comparative neurology, 2003Co-Authors: Brian D. Burrell, Christie L. Sahley, Kenneth J. MullerAbstract:The leech Escape Reflex—shortening of the body—can change with nonassociative conditioning, including sensitization, habituation, and dishabituation. Capacity for sensitization, which is an enhancement of the Reflex, is lost when a single S-interneuron is ablated, but the Reflex response itself remains. In the present experiments, the S-interneuron's axon in the living leech was filled with 6-carboxyfluorescein (6-CF) dye and cut with an argon laser microbeam (λ = 488 nm). In contrast to sham-operated animals, axotomized preparations did not sensitize, reflecting the key role of the S-cell. By 2 weeks or more, S-cell axons had regenerated and reestablished synapses at their usual locations with neighboring S-cells. By 4 weeks, this restored the ability to sensitize to a level indistinguishable from that of controls, but an intermediate state of recovery was seen from 2–3 weeks after injury—a period not previously examined. The small capacity for sensitization among newly regenerated preparations was significantly lower than in sham controls but appeared higher than in animals whose cut S-cell axon had not regenerated its synapse. The results confirm the crucial role of the S-cell in sensitization. Moreover, full sensitization does not occur immediately upon synapse regeneration. J. Comp. Neurol. 457:67–74, 2003. © 2003 Wiley-Liss, Inc.
David L. Glanzman - One of the best experts on this subject based on the ideXlab platform.
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Habituation of the C-Start Response in Larval Zebrafish Exhibits Several Distinct Phases and Sensitivity to NMDA Receptor Blockade
2016Co-Authors: Adam C. Roberts, Jun Reichl, Monica Y. Song, Amanda D. Dearinger, Naseem Moridzadeh, Kaycey Pearce, Joseph Esdin, Elaine D, David L. GlanzmanAbstract:The zebrafish larva has been a valuable model system for genetic and molecular studies of development. More recently, biologists have begun to exploit the surprisingly rich behavioral repertoire of zebrafish larvae to investigate behavior. One prominent behavior exhibited by zebrafish early in development is a rapid Escape Reflex (the C-start). This Reflex is mediated by a relatively simple neural circuit, and is therefore an attractive model behavior for neurobiological investigations of simple forms of learning and memory. Here, we describe two forms of short-lived habituation of the C-start in response to brief pulses of auditory stimuli. A rapid form, persisting for $1 min but,15 min, was induced by 120 pulses delivered at 0.5–2.0 Hz. A more extended form (termed ‘‘short-term habituation’ ’ here), which persisted for $25 min but,1 h, was induced by spaced training. The spaced training consisted of 10 blocks of auditory pulses delivered at 1 Hz (5 min interblock interval, 900 pulses per block). We found that these two temporally distinguishable forms of habituation are mediated by different cellular mechanisms. The short-term form depends on activation of N-methyl-D-aspartate receptor
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Habituation of the C-start response in larval zebrafish exhibits several distinct phases and sensitivity to NMDA receptor blockade.
PloS one, 2011Co-Authors: Adam C. Roberts, Jun Reichl, Monica Y. Song, Amanda D. Dearinger, Naseem Moridzadeh, Kaycey Pearce, Joseph Esdin, David L. GlanzmanAbstract:The zebrafish larva has been a valuable model system for genetic and molecular studies of development. More recently, biologists have begun to exploit the surprisingly rich behavioral repertoire of zebrafish larvae to investigate behavior. One prominent behavior exhibited by zebrafish early in development is a rapid Escape Reflex (the C-start). This Reflex is mediated by a relatively simple neural circuit, and is therefore an attractive model behavior for neurobiological investigations of simple forms of learning and memory. Here, we describe two forms of short-lived habituation of the C-start in response to brief pulses of auditory stimuli. A rapid form, persisting for ≥1 min but