Modulation of Ether-à-Go-Go Related Gene (ERG) Current Governs Intrinsic Persistent Activity in Rodent Neocortical...

Area of Science:

• Neuroscience
• Cellular Electrophysiology
• Ion Channel Function

Background:

• Cholinergic receptor activation enhances cortical neuron excitability, but the underlying cellular mechanisms remain unclear.
• Persistent firing, crucial for cognitive functions like short-term memory, is a common neuronal activity pattern.
• Ether-a-go-go-Related Gene (ERG) channels are primarily studied in the heart, with limited understanding of their role in the brain.

Purpose of the Study:

• To investigate the ionic mechanisms responsible for persistent firing in neocortical pyramidal cells following cholinergic receptor activation.
• To identify the role of Ether-a-go-go-Related Gene (ERG) channels in mediating hyperexcitability and persistent firing in the neocortex.

Main Methods:

• Intracellular recordings were performed in rat neocortical brain slices.
• The effects of chemically diverse ERG channel blockers (terfenadine, ErgToxin-1, E-4031) on neuronal firing patterns were assessed.
• Input resistance and membrane potential changes were measured during persistent firing induction.

Main Results:

• ERG channel blockers abolished persistent firing and increased input resistance in deep pyramidal cells.
• Calcium accumulation during stimulation appeared to attenuate ERG currents, leading to depolarization and persistent firing.
• ERG currents normally oppose prolonged neuronal discharges and enhance poststimulus repolarization.

Conclusions:

• A reduction in ERG K+ channel currents contributes significantly to persistent firing in neocortical pyramidal cells.
• Modulation of ERG channels may underlie various forms of persistent neuronal activity observed in vivo.
• Understanding ERG channel function in the brain is critical, especially given links between ERG mutations and neurological disorders like schizophrenia.