Plasticity of binaural interaction. I. Effect of early auditory deprivation

Abstract

The importance of early binaural stimulation for the expression of binaural interaction in the inferior colliculus of the rat was investigated by unilateral and bilateral sound deprivation. Deprivation was achieved through ligation of one or both of the external auditory meatuses 10 days after birth. After 3-5 mo. of deprivation, the ligatures were removed, and responses of single units in the inferior colliculus were recorded while click stimuli were presented binaurally. The interaural intensity difference of the clicks was varied over a range of 40 dB, in 10 dB steps. Units in animals bilaterally deprived had normal binaural interaction between the antagonistic contralateral and ipsilateral inputs. In the inferior colliculus contralateral to the deprived ear of unilaterally deprived animals, suppression of unit activity evoked by ipsilateral input was dominant over contralateral facilitation. Ipsilateral to the deprived ear, unit activity was essentially unaffected by ipsilateral input. Early asymmetrical deprivation of auditory input apparently results in partial or complete loss of binaural interaction at the inferior colliculus of the rat.