Effect of LMAN on learning of introductory vocalizations produced before the song by male zebra finch

Abstract

Performing motor actions like a tennis serve or a basketball free throw requires coordination between sensory inputs and motor outputs, which is learned through practice and experience through trial and error. Similarly, songbirds like zebra finch learn songs by listening and imitating their father's songs. Their song consists of repeats of a short-duration vocalization, ‘introductory note’ (IN), followed by a consistent sequence of syllables, ‘motifs’. Song learning involves the sensory acquisition and the motor phase. Brain regions involved in the acquisition and production of songs include the anterior forebrain pathway (AFP) and motor pathway. AFP is a cortical-basal ganglia circuit with LMAN as its output brain region. Any disruption to AFP during the song learning phase affects the accuracy of motif copying. However, INs, similar to motifs, have both learned and innate components. Hence, any damage to LMAN in male juvenile zebra finch during the song learning phase may influence IN learning. I performed bilateral electrolytic LMAN lesions on juvenile zebra finches during the song learning phase to check this. Next, I quantified and compared the percentage similarity in IN and motif with the extent of LMAN lesioned. Further, I validated the lesion efficacy by quantifying the volume of LMAN remaining in cresyl violet stained sagittal brain sections. My results suggest that lesions of LMAN affect learning of the acoustic structure of both INs and motifs and the number of INs. However, it is difficult to draw firm conclusions due to the small number of birds.