Multisensory Perception of Self Motion: Psychophysics and Functional Neuroanatomy
Prof. Dr. Mark Greenlee (University of Regensburg)
Abstract. With our sensory systems, we experience our environment through the senses of touch, hearing, sight, smell and taste. In addition, we have a vestibular organ, which informs us about self motion and thus contributes to maintaining balance and posture. We combined caloric vestibular stimulation with visual stimulation to analyze the interaction between the visual and vestibular sensory systems in self-motion perception. We have used these modes of stimulation to study the neural interactions during simulated self motion1. For this purpose, congruent and non-congruent visual-vestibular stimulus combinations are used to investigate their influence on the perception of self motion, on direction discrimination of optic-flow fields and on the corresponding neuronal correlates of the self-motion perception. We have measured brain activity in healthy participants using the method of functional magnetic resonance imaging (fMRI). Moreover, we use the method of diffusion-weighted MRI in conjunction with probabilistic fiber tracking to analyze the anatomical connectivity between vestibular and visual cortical regions. By comparing the structural and functional connectivity of the human brain at rest (i.e., resting state), it will be shown how parts of the visual-vestibular network are interconnected.
Finally, the suppression of the vestibular cortex has been examined during the processing of visual motion. When attention is focused on moving visual stimuli, activity in the vestibular cortex is suppressed. We used the method of repetitive transcranial magnetic stimulation (TMS) and functional MRI to determine the neuronal source of this inhibition in the vestibular cortex. The results of these investigations provide new insights into the multisensory integration of visual and vestibular information in self-motion perception.
Bio. Mark W. Greenlee – University professor (tenured), Institute for Experimental Psychology, University of Regensburg.
Bachelor studies (Wayne State Univ., Detroit MI/USA, 1974-79), Diploma (Masters) in Psychology (Univ. of Freiburg, Germany, 1979-84), Dr. rer. nat. (PhD) (Faculty of Biology, Univ. of Freiburg, 1984-86), Habilitation (Medical Faculty, Univ. of Freiburg, 1989); postdoctoral fellowships 1992-93 in Oslo (Feodor-Lynen Fellow, Alexander von Humboldt Foundation) & 1993-94 at Univ. London (Royal Holloway College, England), 1995-99 Schilling Research Professor (Univ. of Freiburg), 1999-03 Associate Professor (Cognitive Neuropsychology, Univ. of Oldenburg), since 2003 full Professor, tenured (Univ. Regensburg, Experimental Psychology & Methodology), since 2015 elected board member of Regensburg Center of Neuroscience; 2008/2016/2019 Harris Visiting Prof. Dartmouth College (NH/USA).