Every medical student learns that perception relies on neural pathways that link each sense organ - the eye or the ear, etc - to specific parts of the brain, culminating in particular regions of the cerebral cortex that are associated with each sense.
But a major challenge in neuroscience is to understand how sensory signals are transformed as they move from one stage of each pathway to the next. In the visual system, standard techniques have provided considerable insight into this by identifying the different patterns of light and dark which excite neurons at each level of the pathway. However, the same approach has not led to such a clear understanding of how sound feature preferences change across the auditory system, which contains an unusually large number of subcortical stages.
In a new paper published in Current Biology, former DPhil student Michael Lohse, now a Sir Henry Wellcome Postdoctoral Fellow at UCL, Professor Andrew King and Departmental Lecturer Dr Ben Willmore present a simple but ground-breaking technique that enabled them to show exactly how sound information is transformed as it moves from the ear, up through the regions of the auditory system, to the auditory cortex, a high-level region which is crucial for our perception of sound. This approach led to the surprising discovery that much of the high-level, sophisticated processing that is important for the complex functions of the auditory cortex is in fact performed by lower, subcortical brain regions, which have often been thought of as simple relays.
The study by Lohse and colleagues provides surprising new insight into the important and sophisticated contribution of subcortical processing to high-level processing of sound, and also reveals new ways in which the cortex influences subcortical processing. It contributes to an exciting developing picture of the vital roles of subcortical processing and top-down connectivity in our ability to perceive, understand and respond to sounds.
'I am excited to see how other neuroscientists will use our new methods to explore how information is transformed in other parts of the brain, resulting in the brain processes that we need to perceive, think, feel and survive.' Says Dr Ben Willmore, the Oxford team lead author.
Read the article here