Advanced imaging techniques used to map auditory brain structurePress release 5 February 2013
Maastricht researchers published in Nature Communications
Researchers from Maastricht University (UM) have shown for the first time in humans that a ‘tonotopic map’ exists deep in the brain, in the ‘inferior colliculus’. The research team used advanced functional magnetic resonance imaging (fMRI) techniques. In the future, high-resolution functional maps of the inferior colliculus may be used to optimise methods for placing implants in patients with impaired hearing. The research, conducted in collaboration with the Center for Magnetic Resonance Research in Minneapolis, was recently published in the online journal Nature Communications.
The researchers, led by Federico De Martino and Michelle Moerel, used a scanner with an ultra-high magnetic field (7 Tesla) to study the inferior colliculus, an area in the middle of the brain with an 8mm diameter that processes auditory information. They measured subjects’ brain responses to simple sounds at different frequencies and to a broad range of natural sounds (such as human voices, animal cries, musical instruments and environmental sounds). The analysis of this brain activity in the inferior colliculus revealed that the neuronal populations, which respond to different sound frequencies, are arranged in a specific order and thus form a ‘tonotopic map’.
Earlier experiments conducted by the UM researchers have shown that different pitch levels (higher versus increasingly lower sounds) are processed in the auditory system in a systematic way. This is the first time that they have explored the deeper and evolutionarily older areas of the brain. Until now, this type of research could only be conducted on animals because the resolution of imaging techniques (3 Tesla MRI) used in humans was insufficient.
The results of this study pave the way for future studies into the role of subcortical brain structures in the perception of sound. In the future, it may be possible to use the high-resolution functional maps of the inferior colliculus to optimise methods for placing implants in patients with impaired hearing.
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