Amygdala modulation of multiple memory systems: hippocampus and caudate-putamen

Area of Science:

• Neuroscience
• Cognitive Psychology
• Behavioral Neuroscience

Background:

• The hippocampus and caudate-putamen are implicated in different memory systems.
• The amygdala's role in modulating these memory processes is not fully understood.

Purpose of the Study:

• To investigate the distinct mnemonic roles of the hippocampus and caudate-putamen.
• To examine the modulatory influence of the amygdala on hippocampal and caudate-putamen memory processes.

Main Methods:

• Five experiments utilized water maze tasks (hidden and visible platforms).
• Pharmacological manipulations involved post-training intrahippocampal, intracaudate, and intra-amygdala amphetamine injections.
• Preretention intrahippocampal, intracaudate, and intra-amygdala lidocaine injections were used to assess memory blockade.

Main Results:

• Hippocampal amphetamine enhanced hidden platform memory; caudate-putamen amphetamine enhanced visible platform memory.
• Amygdala amphetamine enhanced memory in both tasks.
• Lidocaine injections selectively blocked the effects of amphetamine in the respective brain regions, demonstrating a double dissociation.

Conclusions:

• The hippocampus and caudate-putamen play distinct roles in spatial memory formation.
• The amygdala exerts a modulatory influence on both the hippocampal and caudate-putamen memory systems.