Biology

Dr. Raghav Rajan
Ramalingaswami Fellow, DBT, IISER Pune

Abstract:

All movements are believed to be preceded by “preparatory” neural activity in many brain areas and this activity is thought to be important for initiating movements. Much of this knowledge comes from research on monkeys and rats, where, animals are trained to memorize a sensory cue and then make the appropriate movement (typically a simple reaching or licking movement) after a “GO” signal. While such experiments have yielded many insights, very little is known about how more natural, self-triggered, movements (like human speech or a tennis serve) are initiated.

One well-studied example of a natural, self-triggered, movement is the song of an adult, male zebra finch, a songbird. Song consists of a stereotyped sequence of sounds interleaved with silent gaps and much is known about how song is produced. However, how and where in the brain, song is initiated remains poorly understood. Over the last 6 years, work in my lab has suggested the presence of two preparatory stages before song initiation, namely, (1) gradual changes in neural activity starting ~0.5s before the start of a song bout and (2) a second phase where the bird repeats a simple vocalization multiple times. We have characterized multiple aspects of these two stages and I will discuss these results. Based on these results, we propose that songbirds are an excellent model system to study how the brain initiates natural, self-triggered, movements.