Excitatory postsynaptic potentials trigger a plateau potential in rat subthalamic neurons at hyperpolarized states

Area of Science:

• Neuroscience
• Cellular Electrophysiology

Background:

• The subthalamic nucleus (STN) is critical for basal ganglia circuitry and motor control.
• Understanding STN neuron regulation is key to deciphering basal ganglia function.

Purpose of the Study:

• Investigate the interaction between intrinsic membrane properties and synaptic inputs in STN neurons.
• Characterize the generation and properties of long-lasting plateau potentials in STN neurons.

Main Methods:

• Whole-cell recordings from rat STN neurons (postnatal days 14-20).
• Stimulation of glutamate receptor-mediated excitatory synaptic potentials (EPSPs).
• Voltage-clamp and current-clamp techniques to assess membrane properties and channel involvement.

Main Results:

• EPSPs evoked plateau potentials in a subpopulation of STN neurons in a voltage-dependent manner, requiring hyperpolarization below -75 mV.
• Plateau potentials were inducible by current injection in approximately half of tested STN neurons.
• L-type Ca(2+) channels, Ca(2+)-dependent K(+) channels, and TEA-sensitive K(+) channels were implicated in plateau potential generation.
• The early phase of the plateau potential was robust against perturbations, supporting sustained action potential firing.

Conclusions:

• Excitatory synaptic potentials in hyperpolarized STN neurons can trigger plateau potentials via specific ion channels.
• Approximately 50% of STN neurons possess the capacity to convert transient synaptic excitation into prolonged output firing through this mechanism.