When you read a book and listen to music, the brain doesn’t keep these two tasks nicely separated. In a new article just out, I show that there is a brain area which is busy with both tasks at the same time (Kunert et al., 2015). This brain area might tell us a lot about what music and language share.
The brain area which you see highlighted in red on this picture is called Broca’s area. Since the 19th century, many people believe it to be ‘the language production part of the brain’. However, a more modern theory proposes that this area is responsible for combining elements (e.g., words) into coherent wholes (e.g., sentences), a task which needs to be solved to understand and produce language (Hagoort, 2013). In my most recent publication, I found evidence that at the same time as combining words into sentences, this area also combines tones into melodies (Kunert et al., 2015).
What did I do with my participants in the MRI scanner?
Take for example the sentence The athlete that noticed the mistresses looked out of the window. Who did the noticing? Was it the mistresses who noticed the athlete or the athlete who noticed the mistresses? In other words, how does noticed combine with the mistresses and the athlete? There is a second version of this sentence which uses the same words in a different way: The athlete that the mistresses noticed looked out of the window. If you are completely confused now, I have achieved my aim of giving you a feeling for what a complicated task language is. Combining words is generally not easy (first version of the sentence) and sometimes really hard (second version of the sentence).
Listening to music can be thought of in similar ways. You have to combine tones or chords in order to hear actual music rather than just a random collection of sounds. It turns out that this is also generally not easy and sometimes really hard. Check out the following two little melodies. The text is just the first example sentence above, translated into Dutch (the fMRI study was carried out in The Netherlands).
If these examples don’t work, see more examples on my personal website here.
Did you notice the somewhat odd tone in the middle of the second example? Some people call this a sour note. The idea is that it is more difficult to combine such a sour note with the other tones in the melody, compared to a more expected note.
So, now we have all the ingedients to compare the combination of words into a sentence (with an easy and a difficult kind of combination) and tones in a melody (with an easy and a difficult kind of combination). My participants heard over 100 examples like the ones above. The experiment was done in an fMRI scanner and we looked at the brain area highlighted in red above: Broca’s area (under your left temple).
What did I find in the brain data?
The height of the bars represents the difference in brain activity signal between the easy and difficult versions of the sentences. As you can see, the bars are generally above zero, i.e. this brain area displays more activity for more difficult sentences (not a significant main effect in this analysis actually). I show three bars because the sentences were sung in three different music versions: easy (‘in-key’), hard (‘out-of-key’), or with an unexpected loud note (‘auditory anomaly’). As you can see the easy version of the melody (left bar) or the one with the unexpected loud note (right bar) hardly lead to an activity difference between easy and difficult sentences. It is the difficult version (middle bar) which does. In other words: when this brain area is trying to make a difficult combination of tones, it suddenly has great trouble with the combination of words in a sentence.
What does it all mean?
This indicates that Broca’s area uses the same resources for music and language. If you overwhelm this area with a difficult music task, there are less resources available for the language task. In a previous blog post, I have argued that behavioural experiments have shown a similar picture (Kunert & Slevc, 2015). This experiment shows that the music-language interactions we see in people’s behaviour might stem from the activity in this brain area.
So, this fMRI study contributes a tiny piece to the puzzle of how the brain deals with the many tasks it has to deal with. Instead of keeping everything nice and separated in different corners of the head, similar tasks appear to get bundled in specialized brain areas. Broca’s area is an interesting case. It is associated with combining a structured series of elements into a coherent whole. This is done across domains like music, language, and (who knows) beyond.
[Update 13/11/2015: added link to personal website.]
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Hagoort P (2013). MUC (Memory, Unification, Control) and beyond. Frontiers in psychology, 4 PMID: 23874313
Kunert R, & Slevc LR (2015). A Commentary on: “Neural overlap in processing music and speech”. Frontiers in human neuroscience, 9 PMID: 26089792
Kunert R, Willems RM, Casasanto D, Patel AD, & Hagoort P (2015). Music and Language Syntax Interact in Broca’s Area: An fMRI Study. PloS one, 10 (11) PMID: 26536026
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DISCLAIMER: The views expressed in this blog post are not necessarily shared by my co-authors Roel Willems, Daniel Casasan/to, Ani Patel, and Peter Hagoort.