Understanding auditory learning disabilities
Dr Jennifer Linden, a researcher at the UCL Ear Institute, received a grant from Deafness Research UK to study how neurons in the brain contribute to a specific variation in electrical activity recorded that can be recorded from the scalp.
[Project Grant, 2007-2008]
Known as the mismatch negativity (MMN), the effect occurs only when a change is heard in an ongoing or repeated sound. The MMN is thought to be related to auditory learning and short-term memory for sounds, and can be used to assess sound discrimination ability, even in newborn babies. It has also proven to be useful for identification of central auditory processing deficits, i.e. hearing problems that occur when the brain interprets sounds incorrectly, even though the ear may detect sounds normally.
Abnormal MMN responses have already been observed in a wide range of clinical conditions associated with central auditory processing impairments, including dyslexia, specific language impairment, autism, schizophrenia, and hearing loss. Different types of MMN abnormalities are associated with different disorders, suggesting that the MMN might be used to distinguish different forms of central auditory dysfunction.
Although it has great potential, the diagnostic and clinical value of the MMN is currently limited by our lack of understanding of the neural mechanisms underlying the phenomenon. The aim of this study was to investigate this further by recording the MMN and neural activity in an animal model while it performed a sound discrimination task.
The team successfully identified activity in individual cells that are possible correlates of the MMN. Usually, it is only possible to see an MMN that is the result of the activity of a large population of neurons. The results have enabled the team to apply for further funds for a larger project to compare neural activity with behaviour.
The research should lead not only to new insights regarding the mechanisms of auditory learning and short-term memory for sounds, but ultimately to a new understanding of hearing problems in the many children and adults suffering from auditory learning disabilities and central auditory processing deficits.
