Synaptic responses to CL-constant stimuli. A–D, EPSCs. Top traces, The excitatory responses with different ipsilateral sound intensities. A, Suppression. B, Enhancement. C, Nonmonotonic enhancement. D, No change. BF tones were used. The BF of each neuron was 17.0, 10.5, 12.5, and 4.0 kHz. The sound intensities of contralateral stimuli were 30, 60, 50, and 60 dB. E–G, IPSCs. E, Suppression. F, Enhancement. G, No change. BF of each neuron was 12.5, 10.5, and 11.0 kHz. The sound intensities of contralateral stimuli were 40, 40, and 30 dB. H, The population of each type of responses to CL-constant stimuli in the groups classified by the responses to ABL stimuli. Con, Contra-preferred response; U, U-shaped response; Cen, center-preferred response; N, no ipsilateral response.