A double dissociation revealing bidirectional competition between striatum and hippocampus during learning

Area of Science:

• Neuroscience
• Cognitive Science
• Behavioral Neuroscience

Background:

• The multiple memory systems framework posits distinct neural circuits for different memory types.
• Hippocampal circuits process spatial information, while striatal circuits handle instrumental conditioning.
• Prior research suggests unidirectional competition, where hippocampal disruption enhances striatal learning.

Purpose of the Study:

• To investigate if memory system competition is bidirectional.
• To determine if striatal impairment can enhance hippocampal learning.

Main Methods:

• Utilized excitotoxic lesions and genetic manipulations in mice.
• Impaired dorsal striatal function via lesions or inhibiting cAMP response element-binding protein.
• Disrupted dorsal hippocampal function using excitotoxic lesions.

Main Results:

• Impairment of dorsal striatal function impaired cued learning but enhanced spatial learning.
• Lesions of the dorsal hippocampus disrupted spatial learning and enhanced cued learning.
• Demonstrated a double dissociation, indicating bidirectional competition between memory systems.

Conclusions:

• Striatal and hippocampal memory systems exhibit bidirectional competition.
• This competition supports the parallel operation of distinct memory systems.
• Findings provide strong evidence for the multiple memory systems framework.