Overall area of research
The focus of the Cognitive Neuroscience Laboratory is the processing of sensory information in the central nervous system and the influence of cognitive factors on these processes. The model system we have concentrated on for our research is the highly developed ability to process visual motion information in higher primates.
Research at the Cognitive Neuroscience Laboratory is aimed at understanding the neural basis of visual perception. Vision is an active process that is far more than a passive registration of our environment. Rather, on its way from the eyes to and through the cortex, visual information is heavily modulated by numerous processes that enhance some aspects while diminishing others. This allows us to filter out unwanted information and concentrate the brain's processing abilities on relevant information.
The accurate representation of visual motion in the environment is one of the most important tasks of the visual system. Correspondingly, research in the CNL concentrates on this ability as a model for sensory information processing in general.
We use various techniques. While our emphasis is on recording the activity of neurons in the visual cortex of macaque monkeys and measuring human perceptual abilities with psychophysical methods we also use theoretical approaches and functional brain image.
The visual system of man and other highly evolved animals is an evolutionary success story. In primates as many as 1.5 million axons exit the retina, supplying a wealth of detailed information about the visual environment. Unfortunately, at any given moment much of this information is behaviorally irrelevant. If evolution would not have also endowed the nervous system with mechanisms to control the flow of information, only a small fraction of our processing capabilities could be devoted to critical aspects of the incoming sensory signals. The development of a fovea, a central part of vision with superior accuracy and a disproportionally large cortical representation, combined with the ability to make fast and accurate eye movements to foveate interesting aspects of the visual environment are amongst the sensory specializations aimed at sifting the chaff from the wheat in visual information processing. In addition to these bottom-up mechanisms the visual system uses attention as a powerful top-down mechanism to optimize the use of its processing resources.
The ability to perceive motion is one of the most important abilities of visual systems as motion on the retina conveys a plethora of important cues about predators and preys, about the spatial layout and other properties of objects in the scene but also about the self-motion of an organism. Survival thus often depends on an accurate and fast analysis of motion information. Not surprisingly, the visual cortex of primates contains areas specialized for the representation of visual motion information. In rhesus monkeys, one of them, the medio-temporal area MT, has been intensively investigated. It contains a very high proportion of direction-selective neurons, i.e. cells that encode the direction of motion within their receptive fields.
Our research has concentrated on the neural representation of motion information in this area and how attention changes this representation and consequently visual perception and performance.
Research methods used
In the past, the Cognitive Neuroscience Laboratory has concentrated on two techniques
- Cortical extracellular recordings, i.e. the recording of the activity of neurons in the visual cortex of macaque monkeys and
- Psychophysics, i.e. measurements of human perceptual abilities
Current and future work will also include
- Computational Neuroscience, i.e. approaches that elucidate the theoretical aspects of sensory information processing and
- Functional Brain Imaging, i.e. non-invasive methods that measure the activity of various brain structures.
Specific research directions
Within the field of research outlined above the Cognitive Neuroscience Laboratory has several areas of interest. They include
- The role of attention in modulating visual motion processing
- Attentional, sensory, and perceptual issues in the processing of transparent motion.
- Theoretical, psychophysical, and physiological issues in recovering the 3-dimensional shape of moving objects ('Structure-from-motion')
- The role of the cerebellum in visual motion processing and attentional control
- Perceptual aspects and the neural basis of speed perception
- The influence of neurological diseases on the ability to control and use attention