In a new study, researchers in Australia are challenging the theory that the right hemisphere of the brain is associated with feelings and emotions.

The study, conducted by Dr Sharpley Hsieh and colleagues from Neuroscience Research Australia (NeuRA) and published in the journal Neuropsychologia, discovered that individuals with semantic dementia have a hard time recognizing emotion in music. Semantic dementia is a disease where parts of the left hemisphere in the brain are severely affected.

The researchers examined individuals with Alzheimer's disease, semantic dementia and healthy people without either disease. The team played the participants new pieces of music and asked them whether the song was sad, happy, peaceful or scary.

The researchers took images of the participants' brains using MRI in order to statistically compare the diseased regions of the brain to the answers provided in the musical test.

Individuals with Alzheimer's and semantic dementia find it difficult to distinguish whether a human face looks happy or sad as the amygdala in the right hemisphere is diseased.

The researchers found that participants with semantic dementia also find it difficult to determine whether a piece of music is sad or happy because the anterior temporal lobe in the left hemisphere is diseased.

Dr. Hsieh explained:

"It's known that processing whether a face is happy or sad is impaired in people who lose key regions of the right hemisphere, as happens in people with Alzheimer's and semantic dementia.

What we have now learnt from looking at people with semantic dementia is that understanding emotions in music involves key parts of the other side of the brain as well.

Ours is the first study from patients with dementia to show that language-based areas of the brain, primarily on the left, are important for extracting emotional meaning from music. Our findings suggest that the brain considers melodies and speech to be similar and that overlapping parts of the brain are required for both."

Written By Grace Rattue