Midbrain regions involved in call production in Java sparrows.

Calling has been evoked from the midbrain of Java sparrows by currents of less than 200 micro A. Minimum thresholds were found in the medial nucleus intercollicularis, higher threshold sites surrounded these. Additionally, more ventral sites were found. Calling evoked did not resemble natural calls, but was similar to that produced after bilateral denervation of the syrinx. These results indicate that the nucleus intercollicularis acts as a controller rather than an organizer of calling.