Influence of mRNA and protein synthesis inhibitors on the long-term memory acquisition of classically conditioned earthworms

Hikaru Watanabe, Tomohiro Takaya, Toshinobu Shimoi, Hiroto Ogawa, Yoshiichiro Kitamura, Kotaro Oka

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19 Citations (Scopus)


We investigated the process of memory consolidation following classical conditioning of earthworms. Earthworms were conditioned in paired trials by a weak vibration as a conditioned stimulus (CS), and by light as an unconditioned stimulus (US). The occurrence of a shrinking response upon exposure to the CS increased steadily with the number of paired training trials. When the training procedure was changed by increasing the intertrial interval (ITI), it was found that only those worms trained with a 68 s ITI exhibited long-term memory retention for at least 24 h. The influence of mRNA synthesis inhibition by actinomycin-D or of protein synthesis by anisomycin on memory consolidation was also examined. Induction of the long-term memory was blocked when either of these two compounds was injected into the body cavity of the worm within 25 min of conditioning with the 68 s ITI. These results demonstrate that the long-term memory is dependent upon protein synthesis in response to the upregulation of new transcription messengers.

Original languageEnglish
Pages (from-to)151-157
Number of pages7
JournalNeurobiology of Learning and Memory
Issue number2
Publication statusPublished - 2005 Mar



  • Actinomycin-D
  • Anisomycin
  • Associative learning
  • Memory consolidation
  • Retention of memory
  • Shirinkage response
  • Ventaral nerve cord

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience
  • Behavioral Neuroscience

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