Takemura Lab Seminar: Masaya Harada (University of California, Berkeley, USA)
Date and Time
April 15th, 2026, 1:30-2:30 PM
Format
onsite-only format
Language
Presentation is in English or Japanese, depending on the audience. Slides will be in English.
Speaker
Masaya Harada
Postdoctoral Research Scholar
Department of Neuroscience, University of California, Berkeley, USA
Title and Abstract
Title: A midbrain cholinergic circuit controls the selection of innate defensive behavior.
Abstract: Animals must rapidly select defensive strategies, such as freezing or flight, in response to threatening stimuli, but the underlying neural mechanisms remain unclear. In this study, by comparing laboratory and wild-derived mouse strains, we demonstrate that a midbrain cholinergic circuit dictates the selection of defensive strategies. In response to looming stimuli, the Brazil-derived strain exhibited sustained freezing, whereas the USA-derived strain displayed a high frequency of escape. The superior colliculus (SC) governed this decision via a dual-threshold mechanism: weak activity induced freezing, while strong activity triggered escape. Excitatory cholinergic input from the parabigeminal nucleus (PBG) amplified SC activity via nicotinic receptors, driving the escape tendency observed in the USA-derived strain. Furthermore, local inhibition of nicotinic receptors within the SC selectively abolished escape behavior. These results demonstrate that this midbrain cholinergic circuit acts as a core mechanism shaping the selection of innate defensive behaviors.