Harmony of the neurons

I’ve just finished reading This is your Brain on Music, by Daniel Levitin. It’s a good read, even though it sometimes feels like it was written using an outliner, with sudden changes of topic and facts seemingly thrown in at random.

I’m a non-musician, so I found the parts on the structure of music really interesting. I was quite surprised to find out how arbitrary things like the Western scales are. I always assumed music would tell us a lot about the brain – for instance why should a minor key sound sad – but I didn’t know enough about the subject to find the answers. It does seem to me that music is playing on our innate sense of dynamics, and we interpret melodies using the same mechanisms we use to predict the movement of projectiles and prey, although Levitin seems to think the major/minor thing is mostly just cultural conditioning. He does support this dynamics hypothesis when he talks about the “trajectories” of melody and how different composers use this knowledge to exploit our expectations. Expectation seems to be the key, since he points out that we like music that’s challenging enough to be unpredictable yet simple enough not to sound random. It’s a kind of exercise for the brain that tunes our ability to predict in general.

For me, the most interesting parts relate to memory and classification. He demonstrates that we store cortical schemas consisting only of properties that are invariant. For example, if you try to sing Bohemian Rhapsody you’re very likely to sing it in the right key and at the right tempo. Because you’ve only ever heard the one rendition of it, you store all of its properties in memory. But sing Happy Birthday and it could come out in any old key, because you’ve heard it in so many keys and tempos that your brain only stores the relative notes (or, at least, all the distinct memories interfere to cancel out the key). Key isn’t an invariant property for Happy Birthday but it is for Bohemian Rhapsody, and key is stored separately from melodic shape. This is interesting because sensory invariance is the most striking aspect of perception, and up until now I’ve only thought about it from the angle of vision (e.g. we can recognize an object regardless of its location, scale and orientation). But invariance applies to hearing and touch too, and I hadn’t thought of it in terms of the construction of schemas for categorizing the world at large. It gave me pause for thought.

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About stevegrand
I'm an independent AI and artificial life researcher, interested in oodles and oodles of things but especially the brain. And chocolate. I like chocolate too.

2 Responses to Harmony of the neurons

  1. Ben Turner says:

    Hi Steve – first, I have to say that Creation is one of the reasons I’m in the field I’m in now (computational cognitive neuroscience). However, in a past (and related) life, I was a music student, so I figured I’d put in a few cents, and a plug for my former mentor, David Huron. Since you mentioned expectations, you should check out his book, Sweet Anticipation, which is an entire treatise on the role of expectation in musical emotions. It doesn’t speak too much to the arbitrariness of Western scales (I’m pretty sure he’d say the minor-sad thing is just enculturation, although there are some perceptual features that tie the minor scale to sadness), but it’s a good read. Anyhoo, it’s great that you’ve got an online presence again, and keep it up this time!

  2. stevegrand says:

    Thanks Ben, I’ll certainly check that out.

    I find it hard to believe that the minor scale is sad just because people tell us it is. Intuitively it feels more like we follow the trajectory of notes using brain systems designed for tracking motion, and we sense the “half-heartedness” of its curve, somehow, but I can’t cope with converting from intervals to frequencies to logarithmic frequencies to make sense of it – I’m a musical numbskull.

    Delighted to hear Creation played a part in converting you to computational neuroscience (assuming you’re glad you made the move, of course)!

    Cheers,
    Steve

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