How the brain conquers space
An international research team led by biologist Prof. Andrew Parker from Otto von Guericke University Magdeburg has succeeded in demonstrating, without invasive procedures, how the human brain perceives and processes spatial depth and distances. The scientists used high-resolution magnetic resonance imaging to visualize the activity of small, distinct processing units in humans non-invasively for the first time.
Woman undergoing high-resolution MRI scan to measure brain activity (Photo: Shutterstock)
Bernstein member involved: Kristiane Krug
The study results provide important insights for the diagnosis and possible treatment of central visual disorders that originate not in the eye itself, but in the brain. “We can now track very precisely how the brain processes spatial information,” says Prof. Andrew Parker. “This gives us a better understanding of how depth perception disorders arise and how they could be diagnosed or treated in the future.”
In addition, the work explains a fundamental principle of visual orientation that is important for medicine, robotics, virtual reality systems, and other technological applications. People who can see with both eyes can recognize distances and depth differences, for example, when a ball is flying toward them. The perception of spatial depth arises from the comparison of the slightly different images from both eyes.
It was previously known that individual nerve cells process certain stimuli such as shape, movement, or depth. However, it remained unclear how this information is combined and organized in humans. Prof. Parker’s team has now been able to show that the brain uses individual groups of nerve cells for this purpose, each of which responds to specific characteristics such as shape, movement, or depth. These so-called receptive fields form the basis for processing the many image impressions that our brain assembles in fractions of a second.
For the study, test subjects viewed specially developed 3D patterns while a particularly sensitive MRI device recorded their brain activity. The test subjects lay in a cylindrical channel that generates a strong magnetic field. They viewed the 3D images with a specially developed viewer that presents visual patterns to the left and right eyes independently of each other. When the depth of the patterns was changed, small changes in local blood flow within the visual cortex could be detected with the MR scanner with an accuracy of 1-2 mm.
From this data, the research team reconstructed how the brain processes different depth levels. The activity patterns indicated that the human brain is particularly sensitive to small differences in depth.
The study was published under the title “Receptive fields from single-neuron recording and MRI reveal similar information coding for binocular depth” in the Proceedings of the National Academy of Sciences (PNAS), one of the world’s leading scientific research journals. PNAS publishes peer-reviewed articles from biology, medicine, physics, and related disciplines and is one of the most cited scientific journals worldwide.
Researchers from Otto von Guericke University Magdeburg, the University of Oxford, the Leibniz Institute for Neurobiology in Magdeburg, and the University of Pisa participated in the study.
