The intrinsic membrane properties of the neurons in the cortices of the inferior colliculus were studied in 300-µm transversal slices. The membrane properties, including the sub- and superthreshold, of the neurons were determined by intracellular stimulations with current injections. Of 49 intracellularly recorded neurons, 21 were successfully stained with intracellular biocytin injection. Morphologically all of the 21 neurons were identified as multipolar. Physiologically three firing patterns (onset, regular and adapting) were identified on the basis of response patterns to depolarizing current injections. Onset neurons had a non-linear, and regular and adapting neurons had linear current-voltage relationships. In conclusion, with the multipolar cell morphology and three physiological firing patterns, these neurons may be playing important roles in the processing of sound information mediating the reflexive orienting responses of the eye, head and body.

The intrinsic membrane properties of the neurons in the cortices of the inferior colliculus were studied in 300-µm transversal slices. The membrane properties, including the sub- and superthreshold, of the neurons were determined by intracellular stimulations with current injections. Of 49 intracellularly recorded neurons, 21 were successfully stained with intracellular biocytin injection. Morphologically all of the 21 neurons were identified as multipolar. Physiologically three firing patterns (onset, regular and adapting) were identified on the basis of response patterns to depolarizing current injections. Onset neurons had a non-linear, and regular and adapting neurons had linear current-voltage relationships. In conclusion, with the multipolar cell morphology and three physiological firing patterns, these neurons may be playing important roles in the processing of sound information mediating the reflexive orienting responses of the eye, head and body.