Genetic dissociation of acquisition and memory strength in the heat-box spatial learning paradigm in Drosophila

Learn Mem. 2006 Jan-Feb;13(1):72-83. doi: 10.1101/lm.45506. Epub 2006 Jan 17.

Abstract

Memories can have different strengths, largely dependent on the intensity of reinforcers encountered. The relationship between reinforcement and memory strength is evident in asymptotic memory curves, with the level of the asymptote related to the intensity of the reinforcer. Although this is likely a fundamental property of memory formation, relatively little is known of how memory strength is determined. Memory performance at different levels in Drosophila can be measured in an operant heat-box conditioning paradigm. In this spatial learning paradigm, flies learn and remember to avoid one-half of a dark chamber associated with a temperature outside of the preferred range. The reinforcement temperature has a strong effect on the level of learning in wild-type flies, with higher temperatures inducing stronger memories. Additionally, two mutations alter memory-acquisition curves, either changing acquisition rate or asymptotic memory level. The rutabaga mutation, affecting a type-1 adenylyl cyclase, decreases the acquisition rate. In contrast, the white mutation, modifying an ABC transporter, limits asymptotic memory. The white mutation does not negatively affect classical olfactory conditioning but actually improves performance at low reinforcement levels. Thus, memory acquisition/memory strength and classical olfactory/operant spatial memories can be genetically dissociated. A conceptual model of operant conditioning and the levels at which rutabaga and white influence conditioning is proposed.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / physiology*
  • Adenylyl Cyclases / genetics
  • Adenylyl Cyclases / physiology*
  • Animals
  • Association Learning / physiology*
  • Conditioning, Operant / physiology*
  • Drosophila
  • Drosophila Proteins / genetics
  • Drosophila Proteins / physiology*
  • Eye Proteins / genetics
  • Eye Proteins / physiology*
  • Female
  • Male
  • Memory / physiology*
  • Mutation
  • Reinforcement, Psychology
  • Spatial Behavior / physiology
  • Temperature

Substances

  • ATP-Binding Cassette Transporters
  • Drosophila Proteins
  • Eye Proteins
  • w protein, Drosophila
  • Adenylyl Cyclases
  • Rut protein, Drosophila