In a move almost perfectly timed for Google's celebration of Beethoven's 245th year with a special Google Doodle, MIT announced on Dec. 16 that neuroscientists at the university have pinpointed the neural ensemble in the human auditory cortex that allows humans to select and identify music apart from other sounds, like human speech or general noise.
According to the researchers, there are six respective neural populations (or a collection of connected nervous system cells, also called cultured neurons, that preside over one particular brain computation) that process and separate noise or sounds into categories for us: one for music, one for speech, and then the others for aspects of sound like frequency and pitch.
"One of the core debates surrounding music is to what extent it has dedicated mechanisms in the brain and to what extent it piggybacks off of mechanisms that primarily serve other functions," said Josh McDermott, an MIT professor and one of the scientists on the case.
To come up with a definitive answer, the researchers decided to undertake the almost impossible task of mapping the brain's auditory system, which is difficult to do due to the rough-hewn spatial resolution of fMRI, functional magnetic resonance imaging, which catalogs neural activity by charting blood flow. This activity is measured in voxels, which represent measured activity of millions of neurons with notional three-dimensional space, almost like pixels on a bitmap.
For a data set, the scientists observed the neural activity of 10 human subjects, each of whom listened to around 165 samples of sound. Using their mapping technique helped the team observe and draw up a visual rendition of where this brain activity took place.
"We think this provides evidence that there's a hierarchy of processing where there are responses to relatively simple acoustic dimensions in this primary auditory area. That's followed by a second stage of processing that represents more abstract properties of sound related to speech and music," said Sam Norman-Haignere, a postdoc at MIT's McGovern Institute for Brain Research.
To learn more about how scientists at MIT were able to identify the neural population, check out the video clip below.
Source: MIT
