Brain hub that helps birds learn how to sing 'goes wrong' in people with movement disorders
11:27 GMT, 21 May 2012
The part of the brain which controls how birds learn their songs could be a key to treating disorders such as Parkinson’s disease, a study shows.
Researchers have identitified a ‘smart’ brain structure – the basal ganglia – which helps young finches to learn tunes and correct them if they go wrong.
Once the song is learned motor neurones take over and the song is sung ‘automatically’, much like we learn and perform key movements like walking.
Bengalese finches are thought to learn how to sing and correct their songs using the same area of the brain that we use to perform movements
If the finch hits a dud note it is the basal ganglia which steps in to correct it and the team from the University of California, San Francisco, believe a fault with this part of the brain could be at the root of human movement disorders.
Professsor Michael Brainard explained: 'The basal ganglia can pay attention, observe what other motor structures are doing and get information even when they aren’t involved in motor control.
'They covertly learned how to improve skill performance and this explains how they did it.'
The scientists think problems with this part of the brain could be involved in movement disorders such as Parkinson’s disease and Huntington’s disease.
Actor Michael J Fox who guest starred in Curb Your Enthusiasm last year – was diagnosed with Parkinson's disease in 1991 aged 30
Lead author Jonathan Charlesworth, from the UCSF, said: 'We hope that our findings will help clinicians to interpret the symptoms of these disorders and help scientists to develop more effective treatments.'
To learn its melody, a male songbird uses trial and error to copy its father’s song, singing the tune over and over again, hundreds of times a day – making subtle changes in the pitch of the notes.
A male Bengalese finch begins the training process aged about 40 days and is finished by day 90 – just as he becomes sexually mature enough to woo the ladies with his song.
In order to achieve this, the finch’s brain must receive and process enormous amounts of information about its performance, using the data to control vocal actions which allow it to modify pitch and pattern.
This is where the basal ganlia comes in, researchers say.
Jonathan Charlesworth, a PhD graduate, said: 'It’s the first place where the brain is putting two and two together.
'If you remove the basal ganglia in a bird that hasn’t yet learned to sing, it will never learn to do so.'
Once a simple, repeated skill like typing or singing the same song is learnt, the theory suggests control of that activity is carried out by the motor pathway – the part of the nervous system that transmits signals from brain to muscles.
But if a bird sings another pitch, the basal ganglia must get involved to provide feedback that allows learning based on trial and error.
The researchers made this discovery by blocking the output of a key circuit while training the male finches to alter their song using white noise blasts.
Results showed when the basal ganglia was stopped from sending signals to the motor pathway, the birds did not change their tune or show signs of learning – but when the signals were not blocked, the finches changed the pitch of their song with no practice.
Writing for Nature, the researchers believe their findings support an idea that problems in the basal ganglia’s ability to receive information and learn from it may help movement disorders which form the symptoms of Huntington’s and Parkinson’s.