Critical period for the development and maintenance of binaural interaction

Abstract

A determination of the critical period for the development and maintenance of binaural interaction was made by unit recording at the inferior colliculus of neonatal and sound deprived rats. Collicular units are activated by clicks delivered to the contralateral ear. An indication of binaural interaction in normal adult rats is the suppression of this activity by ipsilateral clicks that are of equal or greater intensity. Such binaural interaction was evident in the unit activity of young rats during the first week after the onset of hearing. Monaural deprivation beginning at 10 days after birth (DAB) and continued for three to five months abolished binaural interaction. The same duration of deprivation had much less effect if begun at 30 days and no effect if initiated at 60 days. The result indicate that the essential connections for binaural interaction are genetically predetermined and present at the onset of hearing at 10 DAB. The critical period for experiential validation of binaural interaction begins at the onset of hearing and extends up to 60 DAB. These conclusions should be considered specific to the rat. [Work supported by NIH Grant NS-13052.]