Ectopic action potentials in regular spiking neurons in the anesthetized mouse.

Area of Science:

• Neuroscience
• Computational Neuroscience

Background:

• Action potentials (APs) typically originate at the axon initial segment (AIS).
• Ectopic APs (EAPs) can also arise in distal axons and propagate antidromically.
• EAPs have been observed in pathological and non-pathological mammalian tissues.

Purpose of the Study:

• To investigate the occurrence of EAPs in layer 2/3 cortical pyramidal neurons in anesthetized mice.
• To compare in vivo EAP generation with previous in vitro findings.

Main Methods:

• Whole-cell current-clamp recordings were performed on layer 2/3 regular spiking (RS) cells in mouse somatosensory and visual cortices.
• High-frequency trains of AIS-APs were induced via direct current injection.
• Ectopic firing patterns were analyzed.

Main Results:

• EAPs were successfully induced in most tested RS cells.
• The incidence and firing profile of EAPs in vivo were comparable to in vitro observations.
• Layer 2/3 pyramidal neurons in anesthetized mice exhibit EAP generation.

Conclusions:

• Pyramidal neurons in layer 2/3 of the mouse cortex can generate EAPs in vivo.
• In vitro studies on EAP generation are valid for assessing neuronal populations' capabilities.
• Findings support the physiological relevance of EAPs in cortical circuits.