Reversal of relative thresholds for synaptic facilitation and increased excitability induced by serotonin and tail nerve stimulation in Aplysia sensory neurons

Silvia A. Bunge, Juliane Mauelshagen, Thomas Carew

Research output: Contribution to journalArticle

Abstract

Tail shock induces reflex sensitization in Aplysia and, in parallel, induces a number of modulatory effects in central neurons, such as increased excitability in tail sensory neurons (SNs) and facilitation of synaptic transmission from SNs to motor neurons. Both of these modulatory effects are mimicked by exogenous application of serotonin (5HT) or electrical stimulation of the tail nerve P9. In the present study we examined the activation thresholds for increased excitability and synaptic facilitation induced by either 5HT or P9 stimulation. We found that the concentration of SHT sufficient to produce a significant increase in excitability produced no significant synaptic facilitation and, conversely, that the intensity of nerve stimulation sufficient to produce significant synaptic facilitation produced no excitability changes. This reversal of relative thresh-olds for these modulatory effects may reflect the differential access of exogenous 5HT and endogenous 5HT (released by tail nerve stimulation) to the SN cell body and synaptic terminals, respectively.

Original languageEnglish (US)
Pages (from-to)259-263
Number of pages5
JournalNeurobiology of Learning and Memory
Volume67
Issue number3
DOIs
StatePublished - May 1997

Fingerprint

Aplysia
Sensory Receptor Cells
Tail
Serotonin
Presynaptic Terminals
Motor Neurons
Synaptic Transmission
Electric Stimulation
Reflex
Shock
Neurons

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Cognitive Neuroscience
  • Experimental and Cognitive Psychology

Cite this

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abstract = "Tail shock induces reflex sensitization in Aplysia and, in parallel, induces a number of modulatory effects in central neurons, such as increased excitability in tail sensory neurons (SNs) and facilitation of synaptic transmission from SNs to motor neurons. Both of these modulatory effects are mimicked by exogenous application of serotonin (5HT) or electrical stimulation of the tail nerve P9. In the present study we examined the activation thresholds for increased excitability and synaptic facilitation induced by either 5HT or P9 stimulation. We found that the concentration of SHT sufficient to produce a significant increase in excitability produced no significant synaptic facilitation and, conversely, that the intensity of nerve stimulation sufficient to produce significant synaptic facilitation produced no excitability changes. This reversal of relative thresh-olds for these modulatory effects may reflect the differential access of exogenous 5HT and endogenous 5HT (released by tail nerve stimulation) to the SN cell body and synaptic terminals, respectively.",
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AU - Carew, Thomas

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