Optical detection of embryogenetic expression of vagal excitability in therat brain stem

We traced and identified the ontogenetic expression of neural excitability related to the vagus nerve in the embryonic rat brain stem. Multiple-site o ptical recordings of neural activities revealed two response areas in the E 12 rat brain stem: one corresponding to the dorsal motor nucleus of the vag us nerve, and the other reflecting the activities of sensory nerve fibers. In embryos younger than E11, no optical response was identified, suggesting that excitability of the motoneurons and/ or sensory nerve fibers is first generated no later than E12. A contour line map of the neural responses su ggested that, in contrast to older embryos, the functional organization of the vagal nucleus is not orderly at the time of the initial expression of n eural excitability. NeuroReport 11:3759-3763 (C) 2000 Lippincott Williams & Wilkins.