Periaqueductal gray and the region of the paralemniscal area have different functions in the control of vocalization in the neotropical bat, Phyllostomus discolor.

The periaqueductal gray matter and the region of the paralemniscal area were neuroanatomically delineated in the brain of the neotropical bat Phyllostomus discolor[Wagner (1843) Arch. Naturgesch., 9, 365-368] and were probed with electrical microstimulation for eliciting vocalizations. In a well-delimited rostral portion of the periaqueductal gray exclusively, communication calls could be triggered at low stimulation currents. Communication calls as well as echolocation calls could be elicited at the dorsal and ventral edges of this area. Pharmacological stimulation with microdialysed kainic acid in this particular periaqueductal gray area demonstrated that neurons and not fibres of passage are activated for triggering vocalization. Solely echolocation calls were emitted upon electrical microstimulation or with microdialysed kainic acid in the region of the paralemniscal area. The periaqueductal gray appears to be involved in vocal pathways that control both communication calls and echolocation calls, while the region of the paralemniscal area seems to be specialized for control of echolocation calls only. Respiration is similarly influenced by stimulation in the periaqueductal gray and the region of the paralemniscal area. Periaqueductal gray and paralemniscal area interact differently with the final common pathway for vocalization, and may represent different functional organization in the vocal controlling pathways for communication calls and echolocation calls.