Approach memory turns to avoidance memory with age

Area of Science:

• Neuroscience
• Developmental Psychology
• Animal Behavior

Background:

• Early memory formation and modification during development are not well understood.
• Key questions remain regarding the influence of acquisition age versus retention age on memory expression.

Purpose of the Study:

• To investigate the ontogenetic modification of early memories in rat pups using odor-shock conditioning.
• To determine if memory output is primarily dictated by the age of acquisition or the age of retention.

Main Methods:

• Odor-shock conditioning was performed on rat pups at post-natal day 6 (P6) and post-natal day 12 (P12).
• Anisomycin was administered post-acquisition to assess memory consolidation and induce retrograde amnesia.
• Retention tests were conducted 24 hours after acquisition, with additional testing at P13 for P6-acquired memories.

Main Results:

• Acquisition at P6 resulted in an approach response, while acquisition at P12 led to an avoidance response when tested 24 hours later.
• Anisomycin injection immediately post-acquisition caused retrograde amnesia at both P6 and P12, confirming memory consolidation.
• A spontaneous reversal of the conditioned response from approach to avoidance was observed for memories acquired at P6 and tested at P13.
• Amnesia induced at P6 was persistent when tested at P13, suggesting stable memory trace alterations.

Conclusions:

• Memory consolidation is an active process in early development at both P6 and P12.
• The maturation and/or competition of memory traces contribute to the observed spontaneous reversal of conditioned responses.
• Developmental stage significantly influences the expression and modification of early learned behaviors.