Phox2b expressing neurons in the most rostral medulla of newborn rats.

Phox2b expressing cells in the parafacial region of the ventral medulla are proposed to play a role in central chemoreception and postnatal survival. We have showed that pre-inspiratory (Pre-I) neurons in the parafacial region (pFRG/Pre-I) in neonatal rats express Phox2b and are postsynaptically CO(2) sensitive. Recent evidence examining Phox2b expression established more clearly the cell architecture of the pFRG, and that Phox2b expression is the most noticeable characteristic of pFRG/Pre-I neurons. Here, we briefly review these recent findings. We also show a unique distribution of Phox2b expressing cells in the most rostral medulla, which could be an interesting target for neurophysiological analysis.