Cholinergic Reinforcement Signaling Is Impaired by Amyloidosis Prior to Its Synaptic Loss

Area of Science:

• Neuroscience
• Alzheimer's Disease Research
• Cholinergic System Function

Background:

• Alzheimer's disease (AD) is linked to amyloidosis and cholinergic system dysfunction, impacting learning and memory.
• The precise nature of acetylcholine signaling in plasticity and its alteration by amyloidosis remains poorly understood.

Purpose of the Study:

• To optically measure acetylcholine release in response to predicted, predicted, and predictive events in the visual cortex of a preclinical AD mouse model.
• To investigate how amyloidosis impacts acetylcholine signaling and its reinforcement qualities before synaptic degeneration.

Main Methods:

• Utilized optical measurement techniques to quantify acetylcholine release profiles in a mouse model of AD with developing amyloidosis.
• Examined acetylcholine signaling in response to unexpected, predicted, and predictive events in the visual cortex.
• Identified and analyzed three distinct stages of amyloidosis.

Main Results:

• Acetylcholine demonstrated reinforcement signaling, reporting behaviorally relevant outcomes and adapting release profiles with experience.
• Cholinergic responses in amyloid-bearing mice were impaired across three stages of amyloidosis, diverging from controls.
• Amyloidosis degraded signaling of unexpected rewards/punishments and attenuated experience-dependent changes in acetylcholine responses to predictive cues and outcomes.

Conclusions:

• Acetylcholine functions as a reinforcement signal that is impaired by amyloidosis prior to cholinergic system degeneration.
• Disrupted cholinergic activity, including transient hyperactivity, may serve as an early functional biomarker for AD.
• Findings enhance understanding of acetylcholine signaling in AD and inform potential therapeutic intervention timing.