Functional ontogeny in the central auditory pathway of the Mongolian gerbil. A 2-deoxyglucose study

The 2-deoxyglucose (2-DG) autoradiographic technique was used to map functional activity in the central auditory system of the mongolian gerbil, throughout the period of functional onset. Uptake of 2-DG during exposure to 105 dB SPL wide band noise (WBN) was compared to silence in adults and in neonates at 12, 14, 16 and 18 days after birth (DAB). At 12 DAB, WBN exposure increased 2-DG uptake relative to silence only in the ventral cochlear nucleus. At 14 DAB, 2-DG uptake increased during WBN in the entire cochlear nuclear complex, superior olivary complex, and ventral nucleus of the lateral lemniscus. These stimulus-evoked increases in 2-DG uptake were at adult levels. However, little or no stimulus-evoked increase was seen in higher auditory nuclei at 14 DAB. By 16 DAB, 2-DG uptake also increased during WBN exposure in the dorsal nucleus of the lateral lemniscus, inferior colliculus and medial geniculate nucleus. By 18 DAB, WBN exposure produced increases in 2-DG uptake of medullary and pontine auditory nuclei which exceeded those seen in adults. At higher levels of the pathway, increases were comparable to those seen in adults. WBN-induced increases in 2-DG uptake observed in the cochlear nuclear and superior olivary complexes of neonates were comparable in all regions at all ages, even at 12 DAB. However, the 2-DG uptake increases observed at 16 and 18 DAB were appreciably greater in those regions of the inferior colliculus and medial geniculate nucleus which respond to high frequencies.