“Listen to this one”: the cerebral mechanisms allowing us to recognise music

A tune comes to our ears, and we immediately recognise it: it’s our favourite song. Is it really? The first notes are familiar, but then a variation occurs, and we understand that it’s a different song. How do we manage to do that? What mechanisms does our brain activate to recognise and even anticipate a series of musical sequences?

The answer is provided by an international group of scholars. With an article published on Nature Communications, this team was the first to shed light on how our brain interprets musical meaning from a sequence of sounds.

"Finding out how the brain recognises and anticipates musical sequences allows us to obtain essential information on the cerebral mechanisms that analyse information as they evolve over time’, explains Leonardo Bonetti, first author of the study and researcher at the Department of Psychology of the University of Bologna, as well as associate professor at the Centre for Music in the Brain, Aarhus University (Denmark), and at the Centre for Eudamonia and Human Flourishing, Oxford University (Great Britain). Bonetti added that ‘the results obtained may be extended to the study of ageing to help us understand how the brain modifies the way of processing information as the years go by. These results may have significant implications for the study of dementia".

Music is an artistic form that gains significance through the combination of sounds, its constitutive elements, over time. Therefore, music is an ideal tool for this type of research. In order to unveil the cerebral mechanisms that enable us to build these musical meanings, the scholars used magnetoencephalography (MEG), a neuroimaging technique that allows for brain activity recording by measuring the magnetic fields produced by the electric currents within it.

The 83 participants in the experiment were presented with some musical sequences to memorise. Subsequently, their cerebral activity was recorded while they listened to both sequences identical to those they had previously memorised and sequences that contained some systematic variations within them.

The results revealed an elaborate net of cerebral areas that are activated and work together to process and recognise music. Starting from the auditory cortex, connections extend to deeper brain regionsinvolved in memory and prevision processes such as the hippocampus, the anterior cingulate gyrus and the medial cingulate gyrus. At the same time, this study highlighted connections that are activated on the opposite direction as well.

"When we listen to a song we know, our brain distinctly responds to every single note that composes the musical sequence, activating an exchange of information from the auditory cortex to the inner parts and viceversa’, explains Bonetti. ‘When the brain detects a variation within a known sequence, a conscious anticipation of the mistake is activated along the same path, with a particularly quick and strong response of the hippocampus and the cingulate gyrus in correspondence with the sounds that introduce the variation".

The functioning of these response mechanisms is in line with the theory of ‘predictive coding’. According to this theory, our brain is constantly at work to make predictions based on incoming sensory information. When these predictions are confirmed, or alternatively, when they are contradicted, several cerebral regions are activated accordingly, each one with specific temporal dynamics and hierarchical relations.

"The predictive coding theory provides us with an important frame to decode the complex cognitive processes of our mind, but quantitative evidence to be able to confirm it in the context of memory are still limited’, concludes Bonetti. ‘The results of this study are a step forward in this direction, as they offer data on the functional hierarchies that are activated in the brain during the recognition of both musical sequences and unexpected variations".

The study was published on the Nature Communications magazine under the title ‘Spatiotemporal brain hierarchies of auditory memory recognition and predictive coding’. Leonardo Bonetti, researcher at the Department of Psychology, participated for the University of Bologna. The study was conducted through an international collaboration between the Universities of Bologna, Oxford, and Aarhus and the Massachusetts Institute of Technology (MIT) of Boston. In addition, it was supported by the Danish National Research Foundation (DNRF), the Carlsberg Foundation and the Lundbeck Foundation.