Features of Action Potentials from Identified Thalamic Nuclei in Anesthetized Patients

Area of Science:

• Neuroscience
• Electrophysiology
• Neuron Science

Background:

• Extracellular action potentials (APs) are crucial for understanding neuronal activity.
• Microelectrode recordings (MERs) are used to capture these electrical signals.
• Deep brain stimulation (DBS) provides an opportunity to study neuronal properties in vivo.

Purpose of the Study:

• To characterize the electrophysiological properties of extracellular action potentials (APs) in human thalamic nuclei.
• To analyze the features of mean action potentials (mAPs) derived from MERs.
• To investigate variations in AP properties across different thalamic nuclei.

Main Methods:

• Collected extracellular action potentials (APs) using microelectrode recordings (MERs) from five patients undergoing centromedian deep brain stimulation (DBS) under general anesthesia.
• Pooled APs from the same cell to generate mean APs (mAPs).
• Quantified amplitudes, durations, first derivative values (dV/dt), and repolarization slopes of mAPs.

Main Results:

• A total of 1109 mAPs were analyzed, predominantly positive (98.47%) and triphasic (93.69%).
• A small positive/negative (P/N) deflection (V1) preceded depolarization in most mAPs.
• Significant differences in mAP percentages and specific relationships between dV/dt and depolarization were observed across thalamic nuclei.

Conclusions:

• Human thalamic nuclei exhibit distinct electrophysiological properties of extracellular action potentials (APs), even under general anesthesia.
• A capacitive current, likely responsible for V1, is common in thalamic APs.
• Subtle differences in repolarization phases are neuron-specific, highlighting regional heterogeneity.