A 2010 paper in "Physics of Life Reviews" speculates that the vocalizations of ancient humans have developed into two forms. The first type is more concrete and became language. The second type is more emotional and became music. The human brain evolved, and the latter "singing" grew more complex.
Functional magnetic resonance imaging, fMRI, is a brain imaging technique used to "see" the brain at work. It reveals the neural structures that are involved during specific tasks such as the processing of music. This protocol is gradually elucidating the neuroanatomy of music.
Auditory Cortex
The primary auditory cortex is located in the temporal lobe on the side of the head. It's the main processing center for sound and music. A 2010 report in the "Proceedings of the National Academy of Sciences of the United States of America" looked at fMRI scans in newborn infants. Two stimuli were presented. Music caused activation in the auditory cortex, whereas noise activated the emotional centers deeper in the brain. These effects reveal that music activates the auditory cortex, and that the ability to differentiate between music and noise occurs at a very young age.
Cingulate Cortex
The anterior cingulate cortex forms a collar around the corpus callosum in the center of the brain. This cingulate controls two distinct types of processes. First, it mediates autonomic responses such as heart rate. Second, it mediates rational behaviors such as decision making.
A 2008 study in the journal "Neuroreport" tested the effects of minor scales on fMRI scans in healthy adults. Minor keys are typically associated with feelings of sadness, and this hypothesis was supported by the brain imaging results. Activation was found in the left parahippocampal gyrus, left medial prefrontal cortex, and bilateral ventral anterior cingulate. Taken together, these structures form part of the limbic system. That area controls emotional responses, and it is activated by music.
Broca's Area
Broca's area is found in the frontal lobe of the brain. It lies along the inferior frontal gyrus. Paul Pierre Broca discovered that injury to this location affects speech. The area also appears important to music. A 2007 investigation in the "Journal of Neuroscience" evaluated the fMRI scans of professional musicians relative to those of control subjects. Both groups were given a three-dimensional mental rotation task. Broca's area was activated only in the musicians. These results suggest that years of musical training has created a circuit in the inferior frontal gyrus which can be drawn upon for other types of learning.
Processing Pathway
The authors of 2009 study in the "Annals of the New York Academy of Sciences" used a different technique to determine the neural structures involved in musical processing. This report looked at electrical changes in the brain caused by listening to music. The auditory cortex was activated within 200 ms. The orbito-frontal cortex was activated within 500 ms. And the limbic system was activated within 1200 ms. These latencies reveal a specific brain circuit for the processing of music.
References
- "Physics of Life Reviews;" Musical Emotions: Functions, Origins, Evolution; L. Perlovsky; March 2010
- "Proceedings of the National Academy of Sciences of the United States of America;" Functional Specializations for Music Processing in the Human Newborn Brain; D. Perani et al.; March 7, 2010
- "Neuroreport;" Music in Minor Activates Limbic Structures: A Relationship with Dissonance?; A. C. Green et al.; May 7, 2008
- "Journal of Neuroscience;" Broca's Area Supports Enhanced Visuospatial Cognition in Orchestral Musicians; V. Sluming et al.; April 4, 2007
- "Annals of the New York Academy of Sciences;" The Birth of Musical Emotion: A Depth Electrode Case Study in a Human Subject with Epilepsy; D. Dellacherie et al.; July 2009
