Response of brainstem trigeminal neurons to electrical stimulation of the dura.

The extracellular response of medullary trigeminal neurons to electrical stimulation of the dura was studied in anesthetized cats. Fifty-six medullary trigeminal units were excited by stimulation sites near major dural vessels with an average latency of 11.0 ms. Many units also responded to infraorbital nerve shock and had cutaneous receptive fields that included the ipsilateral periorbital region. These cutaneous responses were either wide dynamic range or nociceptive specific in type. Electrical stimulation of the midbrain periaqueductal gray region suppressed the response of medullary trigeminal units to either dural stimulation or infraorbital nerve shock. Medullary trigeminal neurons that receive convergent inputs from dura and facial skin may provide a physiological substrate for the cutaneous referral of dural sensation.