Duration tuning in the mouse auditory midbrain

Temporal cues, including sound duration, are important for sound identifica tion. Neurons tuned to the duration of pure tones were first discovered in the auditory system of frogs and bats and were discussed as specific adapta tions in these animals. More recently duration sensitivity has also been de scribed in the chinchilla midbrain and the cat auditory cortex, indicating that it might be a more general phenomenon than previously thought. However , it is unclear whether duration tuning in mammals is robust in face of cha nges of stimulus parameters other than duration. Using extracellular single -cell recordings in the mouse inferior colliculus, we found 55% of cells to be sensitive to stimulus duration showing long-pass, short-pass, or band-p ass filter characteristics. For most neurons, a change in some other stimul us parameter, (e.g., intensity, frequency, binaural conditions, or using no ise instead of pure tones) altered and sometimes abolished duration-tuning characteristics. Thus in many neurons duration tuning is interdependent wit h other stimulus parameters and, hence, might be context dependent. A small number of inferior colliculus neurons, in particular band-pass neurons, ex hibited stable filter characteristics and could therefore be referred to as "duration selective." These findings support the idea that duration tuning is a general phenomenon in the mammalian auditory system.