Cortical tooth pulp evoked potentials in freely moving rat.

Area of Science:

• Neuroscience
• Dental Research
• Animal Models

Background:

• Investigating tooth pulp evoked potentials (TPEP) requires reliable methods for chronic stimulation and recording.
• Previous studies often limited by acute preparations or restrained animal behavior.

Purpose of the Study:

• To develop and validate a method for chronic tooth pulp stimulation (TPS) in rats.
• To characterize tooth pulp evoked potentials (TPEP) in unrestrained animals over several weeks.
• To identify optimal recording sites and factors influencing TPEP amplitude and waveform.

Main Methods:

• Chronic implantation of electrodes in the upper incisor of rats for tooth pulp stimulation (TPS).
• Recording of tooth pulp evoked potentials (TPEP) in the somatosensory cortex of unrestrained rats.
• Systematic exploration of recording sites, stimulus intensity, and electrode placement.
• Acute experiments to assess current spread to the alveolar nerve.

Main Results:

• A reliable method for chronic TPS and TPEP recording in unrestrained rats was established, lasting several weeks.
• The most favorable recording site for high-amplitude TPEPs (1000-2000 µV) was identified in the somatosensory cortex (1 mm anterior of bregma, 3 mm lateral).
• TPEP amplitudes were dependent on behavioral state, stimulus intensity (s-shaped curve), and electrode configuration. Current spread was minimal.

Conclusions:

• Chronic electrode implantation provides a robust model for studying TPEP in awake, behaving rats.
• Somatosensory cortex recordings reveal significant TPEP amplitudes sensitive to stimulation parameters and behavioral context.
• This method facilitates long-term investigations into trigeminal sensory processing and pain mechanisms.