Central Histamine Boosts Perirhinal Cortex Activity and Restores Forgotten Object Memories

Area of Science:

• Neuroscience
• Pharmacology
• Memory Research

Background:

• Establishing methods for retrieving lost long-term memories remains a challenge.
• Central nervous system histamine is crucial for learning and memory; antihistamines impair these functions.
• Histamine H3 receptor inverse agonists may enhance memory by increasing histamine release.

Purpose of the Study:

• To investigate if histamine H3 receptor inverse agonists promote the retrieval of forgotten long-term object memory in mice.
• To explore the underlying mechanisms of memory retrieval enhancement.
• To assess the efficacy of betahistine in promoting memory retrieval in humans.

Main Methods:

• Utilized mouse behavior, calcium imaging, and chemogenetic manipulation.
• Administered histamine H3 receptor inverse agonists (thioperamide, betahistine) to mice.
• Conducted a randomized, double-blind, placebo-controlled crossover trial in human participants.

Main Results:

• Histamine H3 receptor inverse agonists induced recall of forgotten memories in mice up to one month post-training.
• Memory recovery was mediated by histamine release in the perirhinal cortex, activating the histamine H2 receptor.
• Human trials showed inverse agonists were particularly effective for difficult-to-remember items and subjects with poorer performance.

Conclusions:

• Histamine H3 receptor inverse agonists represent a novel therapeutic strategy for enhancing long-term memory retrieval.
• These findings reveal a significant interaction between central histamine signaling and memory engrams.
• The study provides evidence for the role of histamine in memory recall and consolidation.