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Trigeminal responses evoked by painful electrical stimulation
P Svensson1, M Bakke, L Michler
1Department of Prosthetic Dentistry and Stomatognathic Physiology, Royal Dental College, University of Aarhus, Denmark.
Journal of Oral Rehabilitation
|May 12, 1998
Summary
This study investigated trigeminal sensory and motor responses using electrical stimuli in healthy males. Higher stimulus intensity prolonged masseter muscle suppression, indicating altered trigeminal reflex pathways.
Area of Science:
- Neuroscience
- Physiology
Background:
- The trigeminal system integrates sensory and motor functions, crucial for orofacial activities.
- Understanding trigeminal reflexes informs treatments for neurological and pain disorders.
Purpose of the Study:
- To investigate trigeminal sensory and motor responses to varying electrical stimulus intensities and locations.
- To analyze the effects on masseter muscle activity and evoked potentials.
Main Methods:
- 10 healthy males received electrical stimuli (single pulse or 21 ms train) at varying intensities above pain threshold.
- Masseter muscle EMG, bite force, and evoked vertex potentials were recorded during 10% maximal voluntary contraction.
- Stimulation was applied to three distinct perioral regions.
Main Results:
- Increased stimulus intensity significantly prolonged the duration and shortened the latency of masseter muscle exteroceptive suppression.
- Evoked vertex potential amplitude remained unchanged with varying stimulus intensities.
- Both evoked potentials and exteroceptive suppression varied significantly across the three stimulated perioral regions.
Conclusions:
- Trigeminal reflex excitability and central processing are intensity-dependent.
- The spatial distribution of afferent input influences trigeminal sensory-motor integration.
- Results highlight the role of polysynaptic reflex circuits and central processing in trigeminal function.