Basal Forebrain and Brainstem Cholinergic Neurons Differentially Impact Amygdala Circuits and Learning-Related...

Area of Science:

• Neuroscience
• Neurobiology
• Cholinergic System Research

Background:

• The central cholinergic system and amygdala are crucial for motivation and memory.
• Specific roles of distinct cholinergic projections to the amygdala remain incompletely understood.

Purpose of the Study:

• To investigate how different amygdala-projecting cholinergic neurons from the basal forebrain and brainstem impact amygdala circuits and behavior.
• To elucidate the synaptic mechanisms and functional consequences of these distinct inputs.

Main Methods:

• Utilized optogenetic circuit-mapping in choline acetyltransferase (ChAT)-cre mice.
• Performed in vitro photo-activation of ChAT terminals and in vivo electrophysiology.
• Assessed changes in neural activity, receptor activation, and learning-related behaviors.

Main Results:

• Brainstem ChAT inputs to the central lateral amygdala are excitatory via AMPA/NMDA receptors.
• Basal forebrain ChAT inputs to the basal nucleus trigger acetylcholine release, causing biphasic inhibition-excitation and enhancing theta/gamma rhythmicity.
• Brainstem ChAT activation transiently increased central lateral amygdala activity independently of cholinergic receptors, while basal forebrain activation induced opposing behavioral changes in learning.

Conclusions:

• Distinct cholinergic inputs from the basal forebrain and brainstem exert differential control over amygdala function.
• These pathways contribute to emotional memory formation by modulating neural oscillations and driving associative learning.
• Findings provide insights into how the brain encodes salient information via cholinergic modulation of amygdala networks.