Revisiting the supratrigeminal nucleus in the rat.

Area of Science:

• Neuroscience
• Anatomy
• Physiology

Background:

• The supratrigeminal nucleus (Vsup) is crucial for jaw movement control.
• Its precise location and cytoarchitecture in rats have remained undefined.
• Previous studies in cats suggested its role as a premotoneuron pool.

Purpose of the Study:

• To cytoarchitectonically distinguish the rat Vsup from surrounding structures.
• To determine if the Vsup receives central axon terminals from trigeminal mesencephalic nucleus (Vmes) neurons.
• To electrophysiologically identify the Vsup.

Main Methods:

• Examined rat Vsup cytoarchitecture.
• Used transganglionic tracer applications to specific jaw nerves.
• Performed electrophysiological recordings after masseter nerve stimulation.

Main Results:

• Identified Vsup medially adjacent to the trigeminal principal sensory nucleus (Vp).
• Observed dense Vmes primary afferent terminals in Vsup, particularly the medial part.
• Confirmed Vsup identification via evoked potentials following masseter nerve stimulation.

Conclusions:

• The rat Vsup is cytoarchitectonically and electrophysiologically identifiable.
• It exhibits somatotopic termination of trigeminal primary afferents.
• Strong termination of spindle Vmes primary afferents occurs in the Vsup.