The BK-mediated fAHP is modulated by learning a hippocampus-dependent task

Area of Science:

• Neuroscience
• Cellular Biology
• Learning and Memory

Background:

• Intrinsic neuronal excitability is a plastic property modulated by learning alongside synaptic changes.
• Action potential (AP) properties, including height, width, and frequency, are regulated by ion channels.
• The fast after-hyperpolarization (fAHP) influences AP duration and calcium influx, mediated by BK channels in CA1 hippocampal pyramidal cells.

Purpose of the Study:

• To investigate alterations in BK-mediated fAHP in hippocampal neurons following trace eyeblink conditioning.
• To determine the role of BK channels in modulating neuronal firing frequency and intrinsic excitability after learning.

Main Methods:

• Current clamp electrophysiology in hippocampal neurons.
• Analysis of action potential properties and fast after-hyperpolarization.
• In vitro and in vivo assessment of neuronal firing frequency with and without BK-channel blockade.

Main Results:

• Learning trace eyeblink conditioning reduced the fAHP and increased AP duration in hippocampal CA1 neurons.
• BK-channel blockade elevated both evoked (in vitro) and spontaneous (in vivo) firing frequency of CA1 neurons.
• A reduction in BK-mediated fAHP is integral to the increased neuronal excitability associated with hippocampus-dependent learning.

Conclusions:

• The BK channel plays a critical role in controlling intrinsic neuronal excitability.
• Reduced BK-mediated fAHP is a key mechanism underlying increased neuronal excitability after hippocampus-dependent learning.
• Modulation of BK channels contributes to the neural plasticity underlying learning and memory.