The Discovery of a "Music Area" (or something close to it) in the Human Brain
In Distinct Cortical Pathways for Music and Speech Revealed by Hypothesis-Free Voxel Decomposition, authors Sam Norman-Haignere, Nancy G. Kanwisher and Josh H. McDermott announced the discovery of a set of neurons in the human primary auditory cortex which primarily respond to music.
There are various caveats to this discovery, including the limitation that activity of neurons in the human brain is primarily observed via fMRI. Subject to choice of magnetic field strength (a fairly standard 3 Tesla machine was used in the research reported in the paper), each voxel (ie each pixel in the image) represents "hundreds of thousands" of neurons, so our current best views of human brain activity are very fuzzy.
The Six Responses
The authors used a statistical approach which allowed them to identify six distinct components of response in the primary auditory cortex, each component defined by the aspect of sound that it responds to:
- Low frequency sounds
- High frequency sounds
- Fast temporal modulation and coarse-scale spectral modulation
- Fine spectral modulation and slow temporal modulation
The statistical approach used allowed the authors to identify components of response where different components might co-exist within individual voxels. Of course such a voxel represents "hundreds of thousands" of neurons, and one might suppose that individual neurons within such voxels belong primarily to only one of the six response components (but verifying that supposition is way beyond the capability of any existing imaging technology).
Response Component Six: Music
The most significant of the six response components is the last one, component six, which is a response to music. It is significant because this is the first time anyone has convincingly identified a music-specific processing region in the human brain (although past work has found limited evidence for localisation of music processing in the brain, as the paper's authors list in the discussion section of their paper).
Response Component Five: Language
But also of interest is component five, which is a response to the sounds of speech.
What is particularly of interest is the non-language specific nature of this response. That is, component five is a response to the sounds of spoken language, whether or not that language is the native language of the listener.
As it happens, this response is a very close match to the response which I have hypothesized as both an evolutionary pre-cursor to our response to music, and also as a component of the mechanism of language acquisition, where it matters simply for the infant learning language to identify which sounds are language and which sounds aren't language.
I first published this hypothesis about a response to language-like sounds in my blog article Music and Daydreaming (6 May 2015), and I elaborated further on it in later articles, in particular Music, Twin Speak and the Language Prototype, Music and the Language Prototype in a Venn Diagram, Music: The Third Reality and Language, Displacement, and the State of Mind Induced by Music.
Where Do We Go From Here?
My theory does make one prediction about responses to speech and music in infants and in older humans (be it older children or adults), which is:
- The brain of an infant learning its first language will respond to the sounds of spoken language in a manner similar to how people' brains respond to music (at whatever age), whereas the brain of any person past the initial stages of learning a language will not have that response to the sounds of spoken language.
Apparently it is possible to do research involving fMRI scans of young babies, so this is a prediction that could be tested in practice.