DISTRIBUTION OF TRIGEMINAL SENSORY NUCLEUS NEURONS PROJECTING TO THE MESENCEPHALIC PARABRACHIAL AREA OF THE CAT

Horseradish peroxidase (HRP) retrograde tracing experiments in the cat demonstrated projections from the trigeminal sensory nuclei to the mesencephalic parabrachial area (PBA), which is located ventral to the inferior colliculus and dorsal to the brachium conjunctivum and includes the nucleus cuneiformis and the most lateral part of the periaqueductal gray. After HRP injection into the mesencephalic PBA, HRP-labeled neuronal cell bodies in the trigeminal sensory nuclei were mainly distributed in the interpolar and caudal spinal trigeminal nuclei (Vi and Vc) bilaterally with a clear-cut contralateral dominance. In Vi, HRP-labeled neurons were mainly distributed in the lateral and medial border regions. In Vc, labeled neurons were located mainly in laminae I and V.