a The default stimulus used in the present study consisted of a 200 ms CF masker presented at 40 dB above the unit’s threshold, followed by a 20 ms CF probe, with a 10 ms delay between masker offset and probe onset. b Responses of a MNTB single unit (CF = 56 kHz, threshold = 14 dB SPL) to the default stimulus. Horizontal black bars represent the masker (200-ms CF tone at 40 dB above threshold, in this case 54 dB SPL) and probe stimuli (20-ms CF tone at 46 dB SPL). Gray shaded areas indicate the analysis windows used to quantify responses to the stimuli, and to measure spontaneous activity.