Scientists have been able to provide fundamental insight into how the brain changes during critical periods for behavioural learning using high-resolution imaging.
Experts at Duke University Medical Center observed the connections between nerve cells, or synapses, of an anesthetized juvenile songbird right after he heard an adult tutors' song for the first time.
Senior author Richard Mooney, a Duke professor of neurobiology, and colleagues gathered around a laser-powered microscope in a darkened room to track changes to individual dendritic spines, important points of contact between nerve cells.
Mooney said: "We expected to see the building of new spines and loss of old spines accelerate when the juvenile heard a tutor's song for the first time. Instead, we saw exactly the opposite: hearing a tutor song rapidly stabilized previously dynamic synapses."
Lead author Todd Roberts, a postdoctoral fellow in the Department of Neurobiology, added: "Juveniles in which spines were already highly stable weren't able to learn from their tutors."
Mooney said that the songbird brain, like people's brains, is learning for an important goal, which is to perform a highly precise skill.
"Many skills, including communication skills, require great precision if you want to stay in the gene pool. A male songbird has to learn to sing precisely or he won't attract a mate."
The study was published online in the journal Nature.