Spike Afterhyperpolarizations Govern Persistent Firing Dynamics in Rat Neocortical and Hippocampal Pyramidal Cells.

Area of Science:

• Neuroscience
• Cellular Electrophysiology
• Ion Channel Function

Background:

• Persistent neuronal firing is vital for cognitive functions but its termination mechanisms remain unclear.
• Both intrinsic and synaptic mechanisms contribute to persistent activity, yet dynamic regulation is poorly understood.

Purpose of the Study:

• To investigate the ionic mechanisms controlling the duration and termination of persistent neuronal firing.
• To elucidate the role of ether-á-go-go-related gene (ERG) channels and spike afterhyperpolarizations (AHPs) in persistent activity dynamics.

Main Methods:

• Intracellular recordings in rat neocortical and hippocampal brain slices.
• Pharmacological manipulation of ERG and SK channels, and optogenetic activation of cholinergic axons.
• Utilized a closed-loop reactive feedback system to modulate spike afterhyperpolarizations.

Main Results:

• ERG channel dynamics enable persistent firing to outlast stimuli and bridge brief pauses.
• The interaction between ERG conductance and spike AHPs regulates persistent firing duration.
• Amplifying spike AHPs induced spontaneous termination of persistent firing in neocortical and hippocampal neurons.

Conclusions:

• Spike afterhyperpolarizations provide a potent, tunable mechanism for terminating persistent firing.
• This interplay offers a generalizable model for self-terminating persistent firing modes observed in vivo.
• Findings suggest a mechanism for regulating neuronal activity relevant to short-term memory functions.