Descending projections from the thalamus and related structures to the tectum are evolutionarily conserved. Here we characterize basic properties of the mouse auditory thalamotectal pathway and compare them to a homologous pathway in the frog: a species that does not contain a neocortex or an additional corticocollicular pathway. Mouse auditory thalamotectal neurons were found to not stain for the calcium-binding markers typically found in the mammalian thalamus. However, many tectal-projecting cells from the brachium of the inferior colliculus were observed to be GABAergic. In addition, mouse thalamotectal neurons in vitro were found to not demonstrate the low-threshold bursting that is commonly found in thalamocortical neurons. The latter two properties - descending inhibition and lack of bursting - are also found in the frog thalamotectal system. However, these properties are not found in mammalian neocortically-projecting thalamic neurons. Given the divergence of amphibians and mammals hundreds of millions years ago, these data suggest that the thalamotectal projection represents an ancient pathway for providing top-down modulation of acoustic responses in the auditory midbrain. This work is presented in homage to Professor Albert Feng, who pioneered a comparative approach to understanding the auditory system, particularly with respect to the auditory midbrain in amphibians and mammals.
|Original language||English (US)|
|Journal||Proceedings of Meetings on Acoustics|
|State||Published - Nov 2 2015|
|Event||170th Meeting of the Acoustical Society of America 2015 - Jacksonville, United States|
Duration: Nov 2 2015 → Nov 6 2015
ASJC Scopus subject areas
- Acoustics and Ultrasonics