Friday, 20 December 2013

The Musical Brain

2013 BNA Christmas Symposium overview

by Jonathan Smith

How does the human brain distinguish music from noise? What brain regions are active when we react to music? Do we all share an intrinsic musicality? How do you make a duck into a soul singer?

These important questions were discussed this month in an annual Christmas symposium held by the British Neuroscience Association (BNA). Speakers from all over the UK were invited to present their findings on the special relationship between Homo sapiens and music. These talks were also interspersed with live music, refreshments and humorous ‘Christmas Crackers’ such as the latter question asked above. In this article I summarise the research discussed in this exciting symposium.

Distinguishing music from noise by pattern-detection
It’s rare to be in a completely silent environment, even in university exams! Being able to tell apart rhythm from random noise is very advantageous. This is because we can be alerted to someone’s footsteps for example, which can let us calculate all sorts of useful information such as the proximity, speed and even mood of the walker.

Dr Maria Chait from the University College London (UCL) demonstrated that humans are incredibly sensitive to rhythmic, repeating sounds. This is even the case when our attention is diverted to other tasks - showing that there is continuous, sub-conscious processing that is very effective at detecting rhythms in our auditory inputs. This might go some way to explaining why all human societies feature some form of rhythmic musical tradition, including genres like polyrhythmic African drumming and thumping dance floor beats.

The Beat in society
It’s clear that an important component of most music is a regular pulse, or beat. The beat provides a regular structure on which we can build harmonies, rhythms and melodies. As demonstrated by the audience in a clapping task, humans are very good at detecting the beat of a piece of music and then moving in sync with it - in other words, dancing. Any Youtube video search would also reveal that our fascinating ability starts at an early age. What is happening in the brain when we detect a beat?

In studies by Dr Katie Overy of the University of Edinburgh, participants were tested to see if they could tell if the beat was repeated in patterns of fours, threes or twos, corresponding to 4/4, 3/4 and 2/4 times for musicians. Using fMRI scans to show active brain regions, Dr Katie Overy showed that groups of neurons deep inside the brain called the Basal Ganglia are very active when carrying out this task. The Basal Ganglia are highly connected regions that are really important in both sensory and motor processing, so this might be an interesting link between listening and moving to a beat. Not only this, but diseases involving the Basal Ganglia, such as Parkinson’s Disease, result in impaired beat detection. Perhaps by using music in more therapies we can provide better ways of treating Parkinson’s Disease and other Basal Ganglia disorders.

The emotional response to music
As most would agree, the soundtrack to a film deeply influences how a scene is portrayed. For instance, dissonant melodies convey discomfort and fear whereas smooth, major keys give a sense of calm and peace. At its most extreme, a piece of music can literally make our hairs stand up on end and give us the ‘chills’. This strong emotional response was measured by Dr Alan Watson of Cardiff University.

Dr Alan Watson’s lab used lie detectors to find out when we get the chills from a piece of music. This is due to the fact that lie detectors are very sensitive to changes in autonomic nervous system activity, such as sweating and pulse rate. Since our autonomic nervous system changes in response to strong emotions, the lie detector is a nifty way of showing when we get the chills! Using various imaging studies, the researchers were able to show that the chills are accompanied by a huge release of dopamine in the ‘pleasure’ circuits in the brain. This thus helps to explain why we can react so strongly to music.

Congenital Amusia and musicality
Some individuals are unable to enjoy music. Some, for example, even have trouble distinguishing between Happy Birthday and the National Anthem. These people may suffer from a condition called Congenital Amusia, a disorder of interpreting musical patterns. Yet, studies of these unique individuals may uncover just how innate musicality can be in the human brain. Dr Lauren Stewart from UCL collaborated with the BBC to carry out some of these studies.

Using a test called the Montreal Battery, the researchers found that people with this disorder have difficulty distinguishing musical tones compared with controls. They even have some trouble in detecting changes in speech tones, such as a question or a command. The research got more elaborate. The experimenters designed an artificial nonsense language and asked participants to detect if they heard a particular word in a phrase e.g. Pa-ti-ba. Interestingly, amusics were no different to controls, even when the ‘language‘ was replaced by musical tones! This indicates that amusia-sufferers may not have an absolute deficit in distinguishing pitches, but rather a lower confidence when doing so. This also indicates that a form of musicality is present in all individuals but can be honed by constant practice.

Dementia and music
Most of us are acquainted with someone who is going through the pain of dementia. It’s a very isolating ordeal for all involved and it’s expected to get much more common within the next few decades. Is music a good way of maintaining contact with sufferers who are gradually losing other precious memories?

Dr Jason Warren from UCL began by emphasising the complexity of music as a cognitive function. It’s encoded in many brain regions and evokes strong emotional and associative memories of events of that concert, party etc. All types of dementia have unique patterns of brain region damage. For example, Frontotemporal dementia (FTD) has specific damage in the knowledge-encoding temporal regions and the motor and emotion-encoding frontal regions of the brain. It turns out that FTD patients have selective impairments in identifying scary and angry music. This may prove to be an effective diagnostic tool because music is a much more robust memory than current tests using the memory of faces.

Peter Todd of the Alzheimer’s Society gave a fascinating talk about his experiences. He organises weekly singing groups called Singing for the Brain. The only difference here is that the participants are dementia sufferers at all stages of the disease. While it might not seem easy to pull off a group session with this requirement, the results of these groups are very encouraging. The groups have even performed at festivals and for BBC Radio 4! The aim of the groups is to include everyone at a personal level, no matter what level of dementia they are suffering. One heartwarming example of the good effects of these groups is of one patient who had lost his short-term memory. He couldn’t even remember that he had been in a singing group for the last hour! However, after every session, it was clear from his posture and manner that he was very upbeat from singing with the group, despite not being able to remember why! Examples like this emphasise the importance of music in social bonding for potentially lonely individuals going through dementia.

It’s clear that music has been an integral part of human history. This shown by the presence of music in every human culture on Earth and the sheer amount of processing power devoted to music in our brains. The brain is a pattern-seeking machine and it has progressed from interpreting primitive vocalisations in forests to sophisticated music forms. Our emotional connection to music and musicality is preserved to a certain extent in everyone. It also proves to be an effective tool for identifying dementia symptoms and also encourages social inclusion for dementia sufferers.

Oh, and if anyone was curious about how you turn a duck into a soul singer, the answer is: Put it in the microwave until its Bill Withers.