Significance of the paralemniscal tegmental area for audio-motor control in the moustached bat, Pteronotus p. parnellii: the afferent off efferent connections of the paralemniscal area.

Abstract

The paralemniscal tegmental area has been determined in the brain of the New World moustached bat, Pteronotus p. parnellii, by electrical microstimulation eliciting echolocation calls and pinna movements. It is located in the dorsal tegmentum rostral and medial to the dorsal nucleus of the lateral lemniscus and is characterized by medium sized and large neurons. Tracer injections (WGA-HRP) showed that the most intense input to the paralemniscal tegmental area originates in the intermediate and deep layers of the homolateral superior colliculus. The strong projections from the ipsi- and contralateral nucleus praepositus hypoglossus most probably contributes vestibular information. Further inputs in descending order of intensity are from the substantia nigra, the contralateral paralemniscal tegmental area, the putamen, the ventral reticular formation in its lateral portions, the medial cerebellar nucleus and the dorsal reticular formation. Efferent projections of the paralemniscal tegmental area reach the putamen bilaterally, the nucleus accumbens and other parts of the basal ganglia, the pretectal area, the substantia nigra, the intermediate and deep layers of the superior colliculus bilaterally and the tegmental area ventral to it. Connections to the dorsal part of the periaqueductal grey, the cuneiform nucleus and the parabrachial region are important in the context of vocal control, whereas projections to the medial portion of the contralateral facial nucleus may interfere with the control of pinna movement. The findings suggest that the paralemniscal tegmental area is involved in audio-motor control of vocalization and pinna movements in bats; connectional and functional similarities and disparities to tegmental regions described in other mammals are discussed.