CBBS Best Paper of The Year 2016

CBBS spokesman Prof. Dr. Toemme Noesselt (right) presents the certificate and corresponding check to lead author Dr. Ying Huang (middle) and co-author Dr. Artur Matysiak. Photo: OVGU/Harald Krieg and LIN/R. Blumenstein

How does the acoustic working memory function? Award for LIN scientists and CBBS members for best publication of 2016

Language, music, and many environmental sounds consist of a continuous sequence of sound events. In order to be able to recognize meaningful patterns in these sequences, our auditory system must relate the sound events to one another. This requires that individual events have to be stored over some period of time. How our brain accomplishes this short-term storage is still largely unknown and subject of intensive research. So far, there are indications that this storage takes place in certain areas of the frontal lobe in the anterior region of the cerebral cortex. Some researchers, however, assume that involvement of the frontal lobe only is insufficient, because of the high accuracy with which sound events must be recalled, and that the auditory system itself must also be involved in short-term storage.

A research team at the Leibniz Institute for Neurobiology in Magdeburg (Y. Huang, A. Matysiak, P. Heil, R. König and M. Brosch) has now identified neuronal mechanisms in studies on humans and macaque monkeys, which contribute to the short-term storage of sound events in the auditory cortex. The researchers instructed their human and monkey subjects to perform auditory tasks that require memorization of individual tones for a few seconds, and during the performance of these tasks the associated brain activity was recorded. In human subjects, the electromagnetic activity of a relatively large population of nerve cells was acquired by means of magnetoencephalography, a modern imaging method with high temporal resolution; in the monkeys, the electrical activity of individual nerve cells in the auditory cortex was recorded by means of fine microelectrodes. In both series of experiments, it was shown that relevant information is stored in the auditory cortex for a short time, reflected in the fact that nerve cells continue to remain active after the tone has subsided. A crucial part of the success of these studies results from the fact that subjects of both species had to perform several different auditory tasks. By comparing the results within each subject group, it could be excluded that the persisting activity merely reflects other auditory and cognitive processes.

The results are essential for basic research as they allow developing more precise models of the neuronal implementation of short-term memory. They also show that invasive experiments on non-human primates represent an indispensable resource for understanding neuronal mechanisms of memory and other cognitive processes with a spatial and temporal resolution which is currently not accessible in humans. The results could also help to develop new treatment approaches for patients with short-term memory deficits. For example, it could be tested whether such patients, where persistent activity is artificially generated by electric stimulation of the cerebral cortex, improve in remembering sound events.