Retention of an Associative Behavioral Change in
            <i>Hermissenda</i>

Crow, Terry; Alkon, Daniel L.

doi:10.1126/science.694512

Cited by 192 publications

(144 citation statements)

References 26 publications

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“…Graviceptive activity would thus provide for visual activation of circuit interneurons innervating foot muscles and potentially contribute to behavioral plasticity. In Hermissenda, conditioning produces CS-elicited foot-shortening and light-elicited inhibition of ciliary locomotion (Crow and Alkon 1978;Lederhendler et al 1986). Pavlovian conditioning can reconfigure the ciliary circuit that typically supports the positive phototaxis to produce light-elicited inhibition of ciliary locomotion (Crow 2004;Crow andTian 2003b, 2006).…”

Section: Multifunctional Neural Network In Hermissendamentioning

confidence: 99%

Sensory Regulation of Network Components Underlying Ciliary Locomotion inHermissenda

Crow¹,

Tian²

2008

Journal of Neurophysiology

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Crow T, Tian L-M. Sensory regulation of network components underlying ciliary locomotion in Hermissenda. J Neurophysiol 100: 2496 -2506, 2008. First published September 3, 2008 doi:10.1152/jn.90759.2008. Ciliary locomotion in the nudibranch mollusk Hermissenda is modulated by the visual and graviceptive systems. Components of the neural network mediating ciliary locomotion have been identified including aggregates of polysensory interneurons that receive monosynaptic input from identified photoreceptors and efferent neurons that activate cilia. Illumination produces an inhibition of type I i (OFF-cell) spike activity, excitation of type I e (ON-cell) spike activity, decreased spike activity in type III i inhibitory interneurons, and increased spike activity of ciliary efferent neurons. Here we show that pairs of type I i interneurons and pairs of type I e interneurons are electrically coupled. Neither electrical coupling or synaptic connections were observed between I e and I i interneurons. Coupling is effective in synchronizing dark-adapted spontaneous firing between pairs of I e and pairs of I i interneurons. Out-of-phase burst activity, occasionally observed in dark-adapted and light-adapted pairs of I e and I i interneurons, suggests that they receive synaptic input from a common presynaptic source or sources. Rhythmic activity is typically not a characteristic of dark-adapted, light-adapted, or light-evoked firing of type I interneurons. However, burst activity in I e and I i interneurons may be elicited by electrical stimulation of pedal nerves or generated at the offset of light. Our results indicate that type I interneurons can support the generation of both rhythmic activity and changes in tonic firing depending on sensory input. This suggests that the neural network supporting ciliary locomotion may be multifunctional. However, consistent with the nonmuscular and nonrhythmic characteristics of visually modulated ciliary locomotion, type I interneurons exhibit changes in tonic activity evoked by illumination.

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Section: Multifunctional Neural Network In Hermissendamentioning

confidence: 99%

Sensory Regulation of Network Components Underlying Ciliary Locomotion inHermissenda

Crow¹,

Tian²

2008

Journal of Neurophysiology

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“…In Hermissenda, the characteristic biophysical change generated by 9-paired TEs and the subsequent formation of CM has long been associated with an LLD in the B-photoreceptors, as revealed by a single light flash (Crow and Alkon, 1974;Alkon, 1980;Lederhendler et al, 1986). Under all conditions in this study when bryostatin was present and positive behavioral acquisition was obtained, a distinct LLD was demonstrable in the B-photoreceptors.…”

Section: Discussionmentioning

confidence: 63%

“…Individual Hermissenda were trained using a Pavlovian conditioning regime adapted from Crow and Alkon (1974) and Lederhendler et al (1986); see Epstein et al (2004) for details. In brief, animals were placed in covered transparent acrylic trays (16 lanes, each about 0.9 cm wide and deep, and 15 cm long) and then dark-adapted in a closed 10 -12°C incubator for 10 min before training or testing.…”

Section: Behavioral Trainingmentioning

confidence: 99%

Bryostatin Enhancement of Memory inHermissenda

Kuzirian

Epstein

Gagliardi

et al. 2006

The Biological Bulletin

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Abstract. Bryostatin, a potent agonist of protein kinase C (PKC), when administered to Hermissenda was found to affect acquisition of an associative learning paradigm. Low bryostatin concentrations (0.1 to 0.5 ng/ml) enhanced memory acquisition, while concentrations higher than 1.0 ng/ml down-regulated the pathway and no recall of the associative training was exhibited. The extent of enhancement depended upon the conditioning regime used and the memory stage normally fostered by that regime. The effects of two training events (TEs) with paired conditioned and unconditioned stimuli, which standardly evoked only short-term memory (STM) lasting 7 min, were-when bryostatin was added concurrently-enhanced to a long-term memory (LTM) that lasted about 20 h. The effects of both 4-and 6-paired TEs (which by themselves did not generate LTM), were also enhanced by bryostatin to induce a consolidated memory (CM) that lasted at least 5 days. The standard positive 9-TE regime typically produced a CM lasting at least 6 days. Low concentrations of bryostatin (Ͻ0.5 ng/ml) elicited no demonstrable enhancement of CM from 9-TEs. However, animals exposed to bryostatin concentrations higher than 1.0 ng/ml exhibited no behavioral learning.Sharp-electrode intracellular recordings of type-B photoreceptors in the eyes from animals conditioned in vivo with bryostatin revealed changes in input resistance and an enhanced long-lasting depolarization (LLD) in response to light. Likewise, quantitative immunocytochemical measurements using an antibody specific for the PKC-activated Ca 2ϩ /GTP-binding protein calexcitin showed enhanced antibody labeling with bryostatin.Animals exposed to the PKC inhibitor bisindolylmaleimide-XI (Ro-32-0432) administered by immersion prior to 9-TE conditioning showed no training-induced changes with or without bryostatin exposure. However, if animals received bryostatin before Ro-32, the enhanced acquisition and demonstrated recall still occurred. Therefore, pathways responsible for the enhancement effects induced by bryostatin were putatively mediated by PKC.Overall, the data indicated that PKC activation occurred and calexcitin levels were raised during the acquisition phases of associative conditioning and memory initiation, and subsequently returned to baseline levels within 24 and 48 h, respectively. Therefore, the protracted recall measured by the testing regime used was probably due to bryostatininduced changes during the acquisition and facilitated storage of memory, and not necessarily to enhanced recall of the stored memory when tested many days after training.

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“…Hermissenda shows a positive phototaxis expressed by movement toward an illuminated area. If illumination (CS) is paired with high-speed rotation (US), positive phototaxis behavior is inhibited (46). Several groups (47,48) have suggested that application of serotonin might induce the activation of protein kinase C (PKC) known to alter K+ current conductances which ultimately lead to long-term excitability changes in the photoreceptors.…”

Section: A) Serotonin (5-ht)mentioning

confidence: 99%