Binaural Interaction in Human Auditory Steady State Responses, ABR and MLR

Effects of Sleep

Abstract

Binaural interaction (BI) in human auditory 40Hz steady state responses (SSRs), ABR and MLR were measured in the waking state and during sleep of 20 adults with normal hearing. The SSRs were elicited with sinusoidally amplitude-modurated (SAM) tones at 500Hz or with tone-pips of 2-1-2 cycles at the same frequency. ABR and MLR were recorded with the same tone-pips at a stimulus interval of 115ms. Stimulus intensity was fixed at 45dBnHL. BI was represented numerically in the ratio in amplitudes of binaurally evoked responses to summed monaural responses for the right and left ears.
The mean values of RI in the responses were significantly higher (p<0.01) during sleep than in the waking state. The result suggested that sleep acted as a suppressive factor to the BI in the responses. Among the responses, the BI-values became lower in the order, ABR (slow component), SAM-tone SSR, tone-pip SSR, MLR (Pa), both in the waking and sleep states. Significant difference was found during sleep between the BI-values in MLR and each of other 3 responses. However, the significant difference in the BI-values between MLR and tone-pip SSR disappeard in the waking state.