  Intensity-tuned auditory cortex neurons may be formed by intensity-tuned
synaptic excitation. Synaptic inhibition has also been shown to enhance, and
possibly even create intensity-tuned neurons. Here we show, using in vivo whole
cell recordings in pentobarbital-anesthetized rats, that some intensity-tuned
neurons are indeed created solely through disproportionally large inhibition at
high intensities, without any intensity-tuned excitation. Since inhibition is
essentially cortical in origin, these neurons provide examples of auditory
feature-selectivity arising de novo at the cortex.
