Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.26.113373v1?rss=1 Authors: de Filippo, R., Rost, B., Stumpf, A., Cooper, C., Tukker, J., Harms, C., Beed, P., Schmitz, D. Abstract: Serotonin (5-HT) affects multiple physiological processes in the brain and is involved in a number of psychiatric disorders. 5-HT axons reach all cortical areas; however, the precise mechanism by which 5-HT modulates cortical network activity is not yet fully understood. We investigated the effects of 5-HT on slow oscillations (SO), a synchronized cortical network activity universally present across species. SO are observed during slow-wave sleep and anesthesia and are considered the default cortical activity pattern. Combining opto- and pharmacogenetic manipulations with electrophysiological recordings, we discovered that 5-HT inhibits SO within the entorhinal cortex (EC) by activating somatostatin-expressing (Som) interneurons via the 5-HT2A receptor (5-HT2AR). This receptor is involved in the etiology of different psychiatric disorders and mediates the psychological effects of many psychoactive serotonergic drugs, suggesting that 5-HT targeting of Som interneurons may play an important role in these processes. Copy rights belong to original authors. Visit the link for more info