Thursday, 2 February 2012

Musical training protects auditory processing speed

Neurons in the auditory pathway have the fastest temporal responses of any sensory neurons.  And this makes sense:  visual, tactile, taste and smell stimuli don’t change as quickly as sounds do, so the neurons supporting those senses don’t have to be as fine-tuned in time as those that support hearing.

It has been known for a while that the auditory pathway in older brains doesn’t work as quickly as in younger brains, so that, quite apart from actual hearing loss, older people have a harder time understanding speech because they just can’t listen fast enough to be able to properly register to such high-speed auditory input.

But now a new study has shown that musical training can reduce or eliminate this decrease in neuronal processing speed in the auditory pathway.  The study, conducted in the lab of Nina Kraus at Northwestern University compared brainstem auditory responses to the sound “da” in four groups of people:  younger and older non-musicians, and younger and older musicians.  What they found was revealing:  older non-musicians had much slower responses to the transition between the consonant and the vowel in the sound “da”, compared to younger non-musicians.  In contrast, the auditory responses of older musicians were very similar to those of younger musicians.

(Figure from Parbery-Clark, 2012.  Panel A shows the temporal characteristics of the sound “da”, while Panels B and C show the subjects’ brainstem responses to the sound, as measured by EEG)

Musical training therefore acts in a protective fashion to maintain the auditory processing speed of older adults, which undoubtedly helps them to be able to understand speech.  The question now is whether musical training starting later in life can help elderly people regain auditory skills that they have lost.

Parbery-Clark A, Anderson S, Hittner E, Kraus N. (2012) Musical experience offsets age-related delays in neural timing.  Neurobiology of Aging in press, doi: 10.1016/j.neurobiolaging.2011.12.015

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