Neural Mechanisms Underlying Sensitization of a Defensive Reflex in <i>Aplysia</i>

Cleary, Len; Baxter, Douglas A.; Nazif, Fidelma A.; Byrne, John H.

doi:10.2307/1542395

Cited by 11 publications

(10 citation statements)

References 59 publications

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“…In addition, stimuli causing defensive behaviors such as inking and escape locomotion initiate respiratory pumping (Waiters and Erickson 1986). Higher-order interneurons that function as initiators or modulators of defensive reactions such as inking, tailwithdrawal, gill-withdrawal, and inhibition of feeding, also excite the L25 cells that initiate respiratory pumping (Cleary et al 1991). Finally, respiratory pumping apparently occurs as an active component of inking (Waiters and Erickson 1986), a well-characterized defensive response.…”

Section: The Function Of Respiratory Pumpingmentioning

confidence: 99%

“…This circuit is active as part of a number of different behaviors (Cleary et al 1991;Kupfermann and Kandel 1969;Leonard et al 1991 ;Peretz 1969). Two classes of behavior affecting the gill and siphon have been studied in particular detail: 1) defensive withdrawal reflexes elicited by mechanical or noxious stimuli to various parts of the body; 2) respiratoCorrespondence to: Dr. A.J.…”

Section: Introductionmentioning

confidence: 99%

“…Primary afferents eliciting gill and siphon withdrawal have been identified (Byrne et al 1974), as have been interneurons (Cleary et al 1991;Frost et al 1988;Hawkins et al 1981;Mackey et al 1989) and central and peripheral motor neurons driven by these afferents Kurokawa and Kuwasawa 1985a,b;Perlman 1979;Bailey et al 1981). The L25 and R25 interneurons of the abdominal ganglion act as both command ceils and central pattern generators for respiratory pumping (Byrne 1983;Byrne and Koester 1978;Koester 1989).…”

Section: Introductionmentioning

confidence: 99%

“…The L25 and R25 interneurons of the abdominal ganglion act as both command ceils and central pattern generators for respiratory pumping (Byrne 1983;Byrne and Koester 1978;Koester 1989). Neurons that modulate the activity of the L25 and R25 cells, and so change the frequency of respiratory pumping, have also been identified (Alevizos et al 1989(Alevizos et al , 1991Cleary et al 1991;Schaefer and Brownell 1986). However, despite the information available on the circuitry controlling the gill, the natural functions of the behaviors in which gill contractions occur are incompletely understood.…”

Section: Introductionmentioning

confidence: 99%

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Respiratory pumping in Aplysia fasciata as part of an integrated defensive response to increases and decreases in seawater concentration

Levy

Susswein

1993

J Comp Physiol A

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Much of the neural circuitry controlling respiratory pumping in Aplysia has been well characterized, but the function of this movement is incompletely understood. To gain insight into possible functions of respiratory pumping, responses were examined for a 40 min exposure to two stimuli that modulate the movement: 1) increase and 2) decrease in seawater concentration. Thresholds were present for both stimuli to affect respiratory pumping. Above threshold, there were graded increases in the number of pumps elicited. There were decrements in respiratory pump frequency as a function of time exposed to the stimulus. Increased respiratory pumping did not contribute to volume regulation in response to exposure to altered seawaters, but was associated with increased defensive responses, such as escape locomotion (swimming) and inking. In addition, head shock, a well-established noxious stimulus, elicited temporal patterns of respiratory pumping similar to those elicited by altered seawaters. The data indicate that in our experimental conditions, respiratory pumping is elicited as part of an integrated defensive response to noxious seawaters.

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Section: The Function Of Respiratory Pumpingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Respiratory pumping in Aplysia fasciata as part of an integrated defensive response to increases and decreases in seawater concentration

Levy

Susswein

1993

J Comp Physiol A

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“…However, this does not preclude the ocular circadian clock from a role in the circadian modulation of other forms of long-term memory formation such as LTS of the siphon withdrawal reflex, a nonassociative form of learning. In LTS, a noxious stimulus presented to 1 side of the animal leads to an increase in reflex withdrawal of the siphon and tail when the stimulated side of the animal is tested (Byrne, 1987;Cleary et al, 1991;Fernandez et al, 2003). Memory formation by LFI and LTS involves 2 separate neuronal circuits that are not only separated spatially but differ in the type of neurons involved with respect to the nature of neurotransmitters (Cleary et al, 1998;Elliott and Susswein, 2002;Bristol et al, 2004;Cropper et al, 2004).…”

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confidence: 99%

Non-Ocular Circadian Oscillators and Photoreceptors Modulate Long Term Memory Formation in Aplysia

2006

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In Aplysia californica, memory formation for long-term sensitization (LTS) and for a more complex type of associative learning, learning that food is inedible (LFI), is modulated by a circadian clock. For both types of learning, formation of long-term memory occurs during the day and significantly less during the night. Aplysia eyes contain a well-characterized circadian oscillator that is strongly coupled to the locomotor activity rhythm. Thus, the authors hypothesized that the ocular circadian oscillator was responsible for the circadian modulation of LFI and LTS. To test this hypothesis, they investigated whether the eyes were necessary for circadian modulation of LFI and LTS. Eyeless animals trained during the subjective day and tested 24 h later demonstrated robust long-term memory for both LFI and LTS, while eyeless animals trained and tested during the subjective night showed little or no memory for LFI or LTS. The amplitude of the rhythm of modulation in eyeless animals was similar to that of intact Aplysia, suggesting that extraocular circadian oscillators were mainly responsible for the circadian rhythms in long-term memory formation. Next, the authors investigated whether the eyes played a role in photic entrainment for circadian regulation of long-term memory formation. Eyeless animals were exposed to a reversed LD cycle for 7 days and then trained and tested for long-term memory using the LFI paradigm. Eyeless Aplysia formed significant long-term memory when trained during the projected shifted day but not during the projected shifted night. Thus, the extraocular circadian oscillator responsible for the rhythmic modulation of long-term memory formation can be entrained by extraocular photoreceptors. KeywordsAplysia; biological clock; circadian rhythm; memory; sensitization; feeding; ocular; learning Biological clocks regulate most physiological and behavioral aspects of organisms, including sleep, locomotor activity, hormone secretion, metabolism, and long-term memory formation as well as many other processes (Fernandez et al., 2003;Bell-Pedersen et al., 2005;Gillette and Sejnowski, 2005). Circadian modulation of memory formation has been demonstrated in both vertebrates and invertebrates (Valentinuzzi et al., 2001;Chaudhury and Colwell, 2002;Fernandez et al., 2003;Lyons et al., 2005;Chaudhury et al., 2005). Robust circadian modulation of long-term memory formation has been shown in Aplysia using a simple nonassociative type of learning, long-term sensitization (LTS) (Fernandez et al., 2003), and a more complex type of associative operant learning, learning that a food is inedible (LFI) (Lyons et al., 2005). In both cases, long-term memory formation occurred when animals were trained © during the subjective day while little or no long-term memory formation occurred when animals were trained during the subjective night. For both LTS and LFI, the circadian clock modulates events during the induction and consolidation of long-term memory (at the time of training), rather than events during the ...

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