Neural origin of evoked potentials during thalamic deep brain stimulation

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Closed-loop deep brain stimulation (DBS) offers potential for improved treatment of neurological disorders like Parkinson's disease and essential tremor through automated parameter adjustment.
• The evoked compound action potential (ECAP), a signal from activated neurons near the DBS electrode, is a potential feedback mechanism for closed-loop systems.

Purpose of the Study:

• To characterize the evoked compound action potential (ECAP) across various stimulation parameters during deep brain stimulation (DBS).
• To identify the specific neural elements that contribute to the ECAP signal.
• To assess the ECAP's viability as a feedback signal for closed-loop DBS.

Main Methods:

• Recorded ECAPs during thalamic DBS in anesthetized cats.
• Developed and utilized computer simulations to model ECAPs from a population of thalamic neurons.
• Administered pharmacological agents (tetrodotoxin, lidocaine, isoflurane, CNQX, APV, muscimol) to probe the neural basis of the ECAP.

Main Results:

• Experimental and computational ECAPs exhibited similar shapes and correlated characteristics across stimulation parameters (R(2) = 0.80-0.95).
• ECAP signal energy increased with higher DBS amplitudes and pulse widths, and was greater at 10-Hz vs. 100-Hz stimulation.
• Pharmacological interventions confirmed ECAP reflects neural activation extent, synchronization, and postsynaptic potentials.

Conclusions:

• The ECAP signal provides valuable information regarding the type and extent of neural activation during DBS.
• ECAP characteristics are influenced by stimulation parameters and specific neural pathways.
• The ECAP demonstrates potential as an effective feedback control signal for closed-loop DBS systems.