Telemetrically recorded neuronal activity in the inferior colliculus and bordering tegmentum during vocal...

In order to find out whether the inferior colliculus, in addition to its auditory decoding function, also has an auditory gating function in the sense that it treats self-produced sounds differently from external ones, we have explored the inferior colliculus and bordering tegmentum for neurones reacting differently to self-produced vocalizations and vocalizations produced by conspecifics. The experiments were made in the squirrel monkey (Saimiri sciureus), using a telemetric extracellular recording technique which allowed to register neuronal activity in freely moving animals during natural vocal communication. The results show that the neurones of the central nucleus of the inferior colliculus do not react differently to self-produced and group mate vocalizations of the same type. In the external nucleus of the inferior colliculus, in addition to classical auditory neurones, neurones are found which react to the vocalizations of group mates, but not to self-produced vocalizations. In the paralemniscal area just below the inferior colliculus, there are neurones which are active during self-produced vocalization, but not during vocalization produced by other animals. The results suggest that the external nucleus of the inferior colliculus and bordering tegmentum are involved in vocalization-dependent auditory gating processes.