Serge O. Dumoulin
Most of our cognitive abilities are accomplished by about 20 billion neurons located in the cerebral cortex of our brain (see figure on the right). An estimated 20 to 50% of the neurons in the cerebral cortex respond to visual stimulation: visual cortex. The goal of my research is to understand what the neurons in visual cortex are doing and how they give rise to our visual perception.
I mainly use brain imaging techniques such as functional magnetic resonance imaging (fMRI), but also psychophysical, neurophysiological, neuropsychological and other brain imaging (e.g. DTI, MEG, EEG) approaches. The development of new data analysis techniques is an important part of my research. With these new analysis techniques I aim to uncover unique perspectives on our brain and behavior.
My research is centered around three major themes. The first two focus on the organization and the functional properties of our visual system in healthy subjects, whereas the third focuses on the visual system under clinical conditions.
Organization
The brain is organized into separate regions implicated in different functional processes. Knowledge about this organization is essential to understand the brain. In addition, quantitative measurements of the functional organization permit interspecies comparisons, detailed analyses of clinical manifestations, and enhances both the interpretability and methodological power of functional studies by allowing analyses to be localized in, constrained by, or combined in functional units.
Function
I am particularly interested in visual motion and shape perception.
The ability to move is an essential property of almost all animals. With this ability comes the requirement to detect motion of ourselves and others. Image motion provides us with information about our environment, most obviously detection of moving objects. In addition, image motion supports several other visual functions. Relative velocities may be used to distinguish shapes and forms (form-from-motion), and to provide depth-clues (depth-from-motion). Furthermore, visual motion can not only provide information about the environment, but also about the observer's own motion and posture in relation to their environment (optic flow). Thus image motion can be used to provide information about ourselves, e.g. to guide our movements and navigation, and inform us about the environment, e.g. to segment our visual world and detect movements of others.
One of the important roles of our visual system is to detect and segregate objects. Early visual neurons only process visual information in a small part of the total visual field. For example, in primary visual cortex (V1) local, oriented edges from the visual scene are extracted, and V1 has been considered as a bank of oriented filters These filters are the basis of shape perception from which later visual areas reconstruct more meaningful objects.
Clinical
Clinical conditions may alter the organization and function of the human brain. These alterations can provide insights into both the clinical manifestations themselves as well as fundamental principles of the brain. In particular, I am interested in the degree of plasticity of the human brain. In addition, studying clinical populations with new data analysis techniques can also reveal potential diagnostic usages of these techniques.