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Title: Multisensory processing in the ferret auditory cortex
Author: Hammond-Kenny, Amy J.
ISNI:       0000 0004 7232 0185
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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Our perception of events depends on the integration of information derived from different sensory modalities. Functional imaging and electrophysiological studies have shown that multisensory interactions occur even at the level of primary sensory cortices; however their functional significance remains elusive. Therefore, to explore the relationship between multisensory interactions in early auditory cortical processing areas and behaviour, we recorded activity from the auditory cortex during the performance of different auditory-visual tasks. Ferrets were trained by positive operant-conditioning to localise auditory, visual and spatiotemporally coincident auditory-visual stimuli throughout the frontal hemifield and to categorise temporally coincident auditory-visual stimuli according to their spatial congruency. Our results show that the integration of auditory and visual cues results in significantly more accurate and faster localisation responses and that spatial information can be used to merge different sensory stimuli and resolve conflicts between them. This confirmed the ferret as a good model to explore multisensory spatial processing. In total, 509 single units were identified in the auditory cortex of five animals, of which 16% were influenced by visual stimulation. Our results show that modulation of activity in response to changes in auditory stimulus characteristics directly relates to task performance. For example, animals were more likely to correctly localise stimuli when activity increased in the contralateral cortex and decreased in the ipsilateral cortex. The effects of visual co-stimulation were subtle, mainly suppressive and not clearly correlated with performance on either task. A population decoding analysis showed that auditory cortical activity is, however, informative about the task context, since we were able to decode task type from trials that were otherwise equivalent in terms of the stimuli presented. Our results support the existence of multisensory interactions in early auditory processing areas, but suggest that these areas function primarily as auditory feature detectors that operate in a task-dependent manner.
Supervisor: King, Andrew ; Nodal, Fernando Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available