Interpretation affects visual perception
Dr. Hendrikje Nienborg is investigating how visual information is processed in the brain. Her most important finding is that the way we interpret visual information influences visual processing and perception. The neuroscientist uses awake mammals to investigate the mechanisms in the visual cortex that underlie visual perception. Dr. Nienborg was awarded an ERC Starting Grant worth 1.9 million euros for her research into the neural foundations of visual perception.
”We believe that we see what we actually see. Or in other words, our expectations have an influence on and determine what we actually see,” said Nienborg giving the example of a person who is waiting for someone on a misty day and knows that the person will be wearing a red jacket. The person waiting has a blurred, unclear view and will in consequence be specifically looking for something red. If a shape then appears in the distance, the person waiting will automatically see the approaching thing in a reddish hue. Expectation therefore affects what a person actually sees.
Nienborg uses mammals to analyse the signals and neural circuits that affect visual perception. The animals were shown simple picture objects on a screen, such as a disc behind or in front of a ring, and had to discriminate between the different positions of the ring. Initially, the experimental set-up was chosen so that the animals were able to easily discriminate between the position of the ring. The three-dimensional appearance of the pictures was then manipulated so that the animals were unable to reliably discriminate between the two ring positions, a situation similar to that where a person is waiting for someone in a foggy environment. The blurred picture required the animals to guess; sometimes they saw the disc behind the ring and sometimes in front of it. This observation provided Nienborg with new insights, as the picture that the animals saw was always identical, but their interpretation of the sensory input was not. She therefore concluded that the difference in what the animals think they saw must be due to how their brain deciphers visual perception.
What is the role of the cortex?
Nienborg focused on what is happening in the secondary cortex of the brain. Brain recordings revealed that nerve cells that are specialised in 3D depth perception are involved in visual processing.
Based on this finding, Nienborg is now working on a model that is different from earlier views that assumed a bottom-up process, i.e. the direct stimulus-driven perception and transmission of information from the eye to the cortex. Nienborg’s experiments have shown that it is not only the eye that plays a role in how we perceive things, but also how visual information is processed in the cortex. The signals in the higher processing centres in the cortex are called “feedback signals”. Nienborg’s experiments also suggest that even simple visual tasks (e.g. the discrimination between different ring positions) are interpreted in the cortex on the basis of experiences and expectations, amongst other things. These processes are referred to as top-down processes.
Nienborg finds her field of research fascinating, as it almost enables her to read the thoughts of the animals. She can deduce the decision the animals will take with a high level of probability from the activity of single nerve cells. In addition, Nienborg strongly believes that memory and experience influence the processing of visual information.
Returning to Baden-Würrtemberg
Dr. Nienborg uses the ERC Starting Grant of 1.9 million euros to further expand her research. Researchers with at least 2 years of experience since completion of their PhD can apply for European Research Council Starting Grants. The ERC has supported European projects in the field of basic and pioneering research since 2007.
Nienborg, who received an email announcing that she was one of several researchers to be awarded an ERC Starting Grant, was pleased with the award, but it also meant she had to make the difficult decision to stay in the USA or return to Germany. She was informed of the award shortly after completing her PhD at the National Eye Institute of Health (NIH) in Bethesda when she was nearing the end of her contract at the Salk Institute for Biological Studies in San Diego. It was perhaps a good moment to return home. However, she had been offered a professorship in the USA, which would have meant that she could have prolonged her 9-year stay in the USA. At the same time, the ERC Starting Grant offered her the possibility to return to Europe, an opportunity that in the end was difficult to turn down. Nienborg was born in Freiburg and grew up in Lörrach, and first studied medicine in Göttingen in 1996. She has been the head of the research group “Neurophysiology of visual and decision processes” at the Tübingen Centre for Integrative Neuroscience since July 2012.
“It is still too early to say where my research results can be applied,” said Nienborg who believes that her basic research results will nevertheless contribute to gaining a better understanding of dementia and schizophrenia. These disorders are characterised by attention deficits, which in turn suggests that the deficits might also be due to the defective neural processing of visual information, and therefore worth investigating in further detail. Nienborg also envisages that her findings will help in the development of robots inspired by human information processing processes.
Dr. Hendrikje Nienborg
University of Tübingen
Werner Reichardt Centre for Integrative Neuroscience
Tel.: +49 (0)7071/ 29-88846