Measuring Pain-Evoked Brain Activity in Neonates Using a Flat-Tip Probe Coupled to EEG

Begin with a settled infant wearing an electroencephalography, or EEG cap, with electrodes contacting the scalp.

The active electrode is positioned at the skull vertex, the reference electrode behind the left ear, and the ground electrode on the right forehead.

Hold the infant's right hand horizontally.

Record the background EEG to establish a baseline.

Next, take a flat-tip probe connected to a contact trigger device fixed to the EEG recording system and apply a mild pain stimulus to the hand.

The probe sends a signal to the computer, marking the stimulus trigger time.

The stimulus activates nociceptors  — the skin's pain-sensitive sensory neurons — opening ion channels.

This allows positive ion influx, generating action potentials.

These action potentials propagate from the nociceptors through the Aδ fibers and project to the spinal cord, from where they reach the brain.

The active electrode captures the brain signals, generating the EEG that identifies the pain response.