Vision
Vision is the dominant sense in humans. We built our cities and buildings, furnished our homes and offices, and designed our transportation and appliances with the assumption that the users will have full vision - with occasional concessions for the visually impaired. We point at things, play sports, drive cars, and read body and facial expressions.
When we are not actively interacting with our world, we watch television: on average 4 to 5 hours per day. In short, we live in a sighted culture.
The importance of vision is also reflected in our brain. About 25% of the human cerebral cortex is involved in visual processing, which is more than for any other sense. In closely related primates, such as macaques, the relative cortical surface area occupied by the visual system is even larger: about 50%. But the absolute cortical surface area of macaque visual cortex is about 20% of that in humans despite similar numbers of nerve fibers coming from the eyes in both species. The increased number of neurons in the human visual cortex presumably reflects additional visual processing required for uniquely human skills such as language.
Studies of the visual system have a long history. The detailed knowledge of the visual system draws many scientists to vision. These scientists are not studying the visual system per se. They use the visual system either as a model to develop and validate new methods, or they use the visual system to investigate other neural properties, such as attention or consciousness. In short, I study the visual system not just for the sake of vision itself, but also as a model for the rest of the brain and as a rich database to validate new methods.
Representative publicationWandell BA, Dumoulin SO, Brewer AA (2009) Visual cortex in humans. In: Squire LR (ed.) Encyclopedia of Neuroscience. Volume 10: pp. 251-257. Oxford: Academic Press. [html].
Approach
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. These data analysis techniques are inspired by biological models, and focus on extracting more information from the underlying neural population than "activity". With these new analysis techniques I aim to uncover unique perspectives on our brain and behavior.
Representative publicationDumoulin SO, Wandell BA (2008) Population receptive field estimates in human visual cortex. NeuroImage. 39: 647-660.
Recommended (Faculty of 1000 evaluations) by A Hyvärinen (2007) and J Trachtenberg (2008).
Main topics
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. The visual cortex contains many maps of the visual world. These maps cover the occipital lobe, and extend into parietal, temporal and frontal cortex. These visual field maps are linked to functional and perceptual properties of the visual system. Representative publicationsHarvey BM, Dumoulin SO (2011) The relationship between cortical magnification factor and population receptive field size in human visual cortex: constancies in cortical architecture. Journal of Neuroscience. 31: 13604-12612.
Wandell BA, Dumoulin SO, Brewer AA (2007) Visual field maps in human cortex. Neuron. 56: 366-383.
Dumoulin SO, Bittar RG, Kabani NJ, Baker CL, Le Goualher G, Pike GB, Evans AC (2000) A new anatomical landmark for reliable identification of human area V5/MT: A quantitative analysis of sulcal patterning. Cerebral Cortex. 10: 454-463.
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 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.
Representative publicationsDumoulin SO, Dakin SC, Hess RF (2008) Sparsely distributed contours dominate extra-striate responses to complex scenes. NeuroImage. 42: 890-901.
Dumoulin SO, Baker CL, Hess RF, Evans AC (2003) Cortical specialization for processing first- and second-order motion. Cerebral Cortex. 13: 1375-1385.
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, and focus on a variety of conditions that affect the visual system. Representative publicationsLevin N, Dumoulin SO, Winawer J, Dougherty RF, Wandell BA (2010) Cortical maps and white matter tracts following long period of visual deprivation and retinal image restoration. Neuron. 65: 21-31.
Masuda Y, Dumoulin SO, Nakadomari S, Wandell BA (2008) V1 projection zone signals in human macular degeneration depend on task, not stimulus. Cerebral Cortex. 18: 2483-2493.
Dumoulin SO, Jirsch JD, Bernasconi A (2007) Functional organization of human visual cortex in occipital polymicrogyria. Human Brain Mapping. 28: 1302-1312.