Scopolamine infused into perirhinal cortex improves object recognition memory by blocking the acquisition of...

Area of Science:

• Neuroscience
• Cognitive Psychology
• Animal Models

Background:

• Previous studies indicated scopolamine paradoxically improved object recognition memory.
• This effect was hypothesized to result from blocking the acquisition of interfering information.

Purpose of the Study:

• To directly test if blocking acetylcholine receptors in the perirhinal cortex (PRh) prevents proactive and retroactive interference in object recognition memory.
• To further elucidate the role of acetylcholine in the acquisition of object information.

Main Methods:

• Modified the spontaneous object recognition memory task to introduce interfering objects before the sample phase (proactive interference) or during the retention delay (retroactive interference).
• Administered intra-PRh infusions of scopolamine, a muscarinic receptor antagonist.
• Assessed the impact of scopolamine on object recognition memory under conditions of proactive and retroactive interference.

Main Results:

• Presentation of an interfering object during the retention delay disrupted recognition (retroactive interference).
• Intra-PRh scopolamine infusions prevented this retroactive interference.
• Presentation of an interfering object before the sample phase disrupted recognition (proactive interference).
• Intra-PRh scopolamine infusions prevented this proactive interference.

Conclusions:

• Blocking muscarinic cholinergic receptors in the PRh disrupts the acquisition of interfering object information.
• This disruption facilitates object recognition memory by reducing interference.
• Provides strong evidence for acetylcholine's critical role in acquiring object information within the PRh.