Researchers: Alexander Fingelkurts, Andrey Fingelkurts, Iiro Jääskeläinen, Christina Krause, Natalia Lebedeva, Riikka Möttönen, Klaus Riederer, Jukka Saari, Mikko Sams, Kaisa Tiippana
Our neurophysiological studies focus on the investigation of the neural basis of audiovisual speech perception. Our aim is to find out in which brain areas, and at which stage of information processing, auditory and visual features of speech are integrated. Two experiments have been done using the 306-channel neuromagnetometer in the Low Temperature Laboratory.
In the first experiment the relation of speech production and visual speech perception was investigated by using the 'Talking Head' (see below for a description) as a stimulus. The results suggest that motor cortical areas are activated during perception of visual speech. The second experiment focused on the role of auditory areas in audiovisual speech perception. We found out that the change in visual features of speech, which gave rise to an illusory change in auditory perception, activated auditory areas.
|Figure 40: The neural activation in the auditory areas of the left hemisphere elicited by a change in visual speech|
Individual HRTFs have been applied for the investigation of the brain activation while auralizing filtered pink noise in the frontal and right hemispheres. The sound was reproduced by a set of custom-made high quality tube headphones (Unides Design Ay.) and the recordings were made with the 306-ch MEG instrument. The special interest is in comparing the metrics in the cortical representations of the different three-dimensional auditory spaces, i.e., front-back, left-right and horizontal planes. This work is done in collaboration with the Brain Research Unit at the Low Temperature Laboratory, HUT.
We have also done preliminary experiments using a multi-channel optical imaging device, which measures the hemodynamic changes in the brain. Our EEG laboratory is ready and an experiment investigating the relation between memory processes and audiovisual speech perception will be started during spring 2001.