Learning movement sequences with music changes brain connectivity. Behavioural relevance pending…

Research Spotlight #2 Moore, E., Schaefer, R., Bastin, M., Roberts, N., & Overy, K. (2017). Diffusion tensor MRI tractography reveals increased fractional anisotropy (FA) in arcuate fasciculus following music-cued motor training. Brain and Cognition, 116, 40-46. 

A couple of weeks ago my mum emailed me a link to a BBC news article which she rightly knew would be of interest to me. It reported on a study by researchers mainly from the University of Edinburgh, and the title of the BBC article was: “Learning with music can change brain structure, says study“. This of course grabbed my attention, as I thought it could provide a neuroscientific counterpart to my PhD student John Dyer’s recent work, which had found that triggering a melody with one’s movements helped in learning and recalling a complex bimanual coordination task (tracing a diamond with one hand and a triangle with the other to create a 4:3 rhythm). The study by Moore et al. on which the BBC article was based is indeed interesting, but probably creates more questions than it answers. It also ties in neatly with an ongoing issue in neuroscience – trying to draw conclusions from neural measures when the behavioural framework within which they should fit is incomplete.

The study involved people learning different patterns of finger movements on their left (non-dominant hand), e.g. index-ring-middle-pinkie-ring-index-ring-middle. You can try yourself and see that it is not that easy – hence room for some learning to happen. Everyone in the study learned the task with a kind of Guitar Hero style video to show them which order the fingers had to be pressed. Importantly, one group practiced with just the video (‘control group’), while the other additionally heard musical pitches (presumably like keys on a piano) to indicate the finger order of the sequence to press. This was the key difference between the groups – one had a ‘musical’ version of the task while the other didn’t. They learned the sequences at home, and the task sped up as they got more confident at producing the sequences. They were tested at performing the rehearsed sequences as well as some sequences that they hadn’t rehearsed at three stages: before training, midway through training and after training. MRI scans of their brains were also recorded before and after training. These were used to measure changes in the organisation of fibres which connects neural cells between the auditory and motor regions of the right-hemisphere of the brain (i.e. the side of the brain which would be responsible for sending muscle signals to the left hand). The hypothesis was that learning with the musical sounds may entail greater auditory-motor linkages in the brain hemisphere involved in coordinating the task-to-be-learned.

The results of the study showed that both groups got better at the task, that is, they completed a greater number of correct sequences as a result of training. However, there were no differences in how much the music and control groups improved, that is both groups were getting pretty much the same number of correct sequences by the end of training. This is rightly taken to show that the musical tones did not influence learning (at least in terms of correct sequences). There was also evidence of a training-dependent change in the organisational structure of the axons connecting auditory and motor regions of the brain for the musical group in the right hemisphere, but not in the left hemisphere or at all in the control group. It could be noted that the changes in neural organisation were small (4% change in the main measure, all measures hovering around the 0.05 p-value), but for such a ‘light’ intervention, this may be all the more compelling – if just adding a little music to the task can change the brain, imagine what you could do if you really went to town with musical movement training!

As I said earlier, these results are certainly interesting. The lack of difference in the learning measure between the group, when one might expect the sound to be helpful, points to a need to understand better if and how sound could lead to enhanced learning of the task (e.g. through movement sonification rather than just as a guide). Also, the apparent change in neural fibres in the music group, although small, may represent a fairly surprising amount of neural plasticity in such a short space of time, more than would be expected (although I cannot comment on whether a 4% difference is that surprising or not as I am not up on what counts as small/large changes in neuroplasticity measures).

In spite of these interesting aspects, there are some limitations on what can be taken from this paper and a number of further questions raised. Firstly, it is a shame that the performance of the task was only examined using correct sequences performed. While it is always a good idea to have a primary learning measure, other measures like timing accuracy or movement kinematics may have revealed group differences which would help with understanding what the neural changes correspond to. If the neural changes are not functional for the movements involved, but rather underpin some audio-motor mapping or association which is simultaneously being acquired by the learners, then this might have been examined by looking for disruptions in performance for the music group when an incongruous finger-tone mapping is introduced following training. It is also possible that using movement sonification (fingers trigger the sounds), rather than sounds as mere cues, may have led to enhanced learning for the music group. Each of these additional measures or experimental conditions might have led to observable behavioural effects, through which the neural changes could be interpreted. As it is, however, it cannot be determined yet whether the observed changes in brain have some functional significance, or are merely an artifact, comparable to an indentation in one’s middle finger following a period of intensive handwriting.

To be fair, the authors do acknowledge that the lack of measured learning differences between the two groups limits the conclusions that can be made with regard to the neural data. Nevertheless, they do propose that the study may be valuable for clinical practice, e.g. for movement rehabilitation in Stroke survivors. The mismatch between the excitement over the seeming neural transformation (less in the paper itself but more in its media coverage) and the lack of corresponding behavioural differences between the learning conditions is telling. Recently, a group of pretty eminent neuroscientists published an excellent critique of a trend in the neurosciences to focus disproportionately on the activity and structures of individual neural cells, or networks of cells, without giving due attention to the situated task and behaviour of the organism that such neural activity is supposed to subserve. Studying the properties of stomach acid molecules is supposed to help us understand digestion; studying the brain should help us understand behaviour.

One might ask – if the researchers had carried out the study as a purely behavioural experiment, would they have then been motivated to repeat it with MRI analysis? My guess is that the behavioural component would need to have been more convincing, in which case the cart may be in front of the horse on this one.

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Musicians keeping together in time

I gave a guest lecture yesterday on the topic of ‘Action’ in Music Psychology. This was for a colleague/friend, Trevor Agus, who runs a course called Music Psychology for students enrolled on Music programmes in the School of Arts, English and Languages. We amuse ourselves that he teaches Music Psychology to music students, while I teach Psychology of Music to psychology students. This was the second time I have given this class.

It is an odd thing for me to teach a class on Psychology of Action to music students, not least because I almost could have become a music student myself at one point in my life. Instead, I became a student of philosophy and psychology, and then movement, and then movement in music, etc. Ah, well. It feels very different trying to impart a message about motor coordination and skill acquisition to musicians than to impart the same message to psychologists. The things that feel the need for emphasis differ, and the ideas that capture the room differ too.

One idea from the class that I was happily reminded of in preparing for it is the complex challenge of musicians coordinating with each other in ensemble performance. It is a miraculous thing enough that one nervous-muscular-skeletal system can coordinate its own behaviour to give rise to musical performance, but it is even more miraculous that many of these systems can not only coordinate their own sounding actions, but also coordinate with each others’ actions. Much of the research into this phenomenon is focussed on either measuring timing between musicians (e.g. the correlations of note interval variations between musicians), or on identifying the perceptual signals that might support musicians in the task of interpersonal musical coordination. In the latter case, the visual cues from body movements and gestures (both intentional and unintentional) seem to play a pretty big part in helping musicians to stay coordinated with each other while enacting a performance.

An example of this that I used in the class is from a concert by the Penguin Cafe Orchestra filmed for the BBC in the mid-80s. In the performance of Air á Danser, a section of the piece involves the group slowing down together a couple of times, then speeding back up to resume the flow of the music. Simon Jeffes, the leader of the group, conducts this process through a combination of head movements, eye contact and body gestures, with the result that around a dozen separate musicians are able to control the timing of their actions as a single unified system. The video clip of the whole track is embedded below, and the section in particular begins at around 1:05. It’s a lovely example of multisensory interpersonal coordination in musical performance, as well as being a very charming piece of music (in my opinion, at least).

Instruments as (complex) landscapes

Today, I attended a very interesting seminar by Dr Scott McLaughlin at the Sonic Arts Research Centre, titled ‘Material Cartographies as Composition’. Scott discussed his approach to musical composition, which involves using multi-stable/chaotic properties of instruments or sound-producing materials (e.g. mics and speaker feedback) as the basis of his compositions. The complex interactions between performers and such chaotic or multi-stable systems forms the topology/cartography/landscape* over which each piece unfolds. A key idea is that once a landscape of interaction is set-up, e.g. by bringing a skilled musician to an ‘instrument’ that responds in a determinate-but-chaotic way, unpredicted sonic things can happen within a reasonably constrained set of conditions. A nice example presented was of a guitar player controlling feedback by moving the guitar around in front of an amplifier. This has the effect of changing the pitches of the feedback in ways that are constrained by the laws of physics, but which are not straightforward to control, given all the complex parameters involved (guitar string tension, resonant frequencies, millimetre distance between guitar and speaker, etc.).

I liked Scott’s approach, particularly the fact that he seemed to have a genuine interest and respect for the ideas he imports from complex systems theory, rather than merely applying the terminology in its colloquial use. However, one question which I had was the degree to which these instruments or landscapes are learn-able to a performer. That is, are the compositions simply the accidents of imparting energy into a complex responding system, or could a user acquire some degree of mastery of the systems? This is an important question for me, coming at this from the perspective of a psychologist interested in skill acquisition. Understanding if and how musicians can learn to perceive and manipulate the regularities (invariant patterns) in complex systems may help in understanding skilful adaptability in lots of areas of life, not just in experimental music.

Part of Scott’s answer to this question, which I think is a useful starting point, is to think of games. Take card games. Even though the rules of a game of poker might be constant, no two poker matches are identical**. Hence, individual poker matches are deterministic but chaotic systems (in some description). When people first start to learn the game, play often faltering, clumsy, and unsatisfying. Over practice, as the patterns and outcomes become perceivable and players learn to detect and act on these, more fluid and satisfying play ensues. In a sense, skilled poker players are experts in managing chaotic, complex systems. While this is a useful analogy, card games generally do have a number of explicit rules which can anchor the learner in discovering the more complex patterns that emerge during different iterations of game-play. With highly indeterminate, complex systems – like some of the instruments Scott described – it is not quite as clear what would anchor a musician’s behaviour in order to get the process of learning off the ground.

Another point Scott made would be that the cultural context of practice in which the musician is skilled, and in which the performance occurs, may also constrain this process. This is a very interesting idea, one that I have become increasingly interested in. However, my challenge, as a psychologist, is going to be figuring out how to scientifically research such a multifaceted problem. This issue is something I will probably devote quite some space to on this blog towards, in the hope of get this research question off the ground.

A final point from today’s seminar that I want to mention here is Scott’s response to a question from Paul Stapleton. As Scott was talking, Paul and I were sat next to each other, and a number of times we spotted ideas that resonated with our own discussions around musical improvisation and skilful adaptability. Paul asked why Scott had not mentioned ‘improvisation’, given how relevant it seemed to the ideas in the seminar. Scott replied that he had found that when he tried to explicitly instruct musicians to improvise in his topology/landscape compositions, the results had generally been ‘shit’. This creates a very interesting question about improvisation as something that interaction within a complex system requires (to manage all the unpredictable fluctuations and chaotic behaviours) versus improvisation as intentional variation within a relatively stable, predictable set of constraints. I cannot yet decide if these are two separate senses of ‘improvisation’ or two flavours of a common concept. Hmmm….

 

*these terms were used semi-interchangeably, with acknowledgment of important conceptual distinctions

**this is true, at least in part, because the likelihood of two shuffles of a deck of cards producing the same ordered deck is astronomically small.