Impaired visual signals might contribute to schizophrenia
By observing the eye movements of schizophrenia patients while playing a simple video game, a VCH Research Institute and UBC researcher has discovered a potential explanation for some of their symptoms including difficulty with certain everyday tasks.
Dr. Miriam Spering, lead on the study and research scientist with the Brain Research Centre, showed that compared to healthy control participants, schizophrenia patients had a harder time tracking a moving dot on a monitor and predicting its trajectory. However, the impairment of their eye movements was not severe enough to explain the difference in their predictive performance, suggesting a breakdown in their ability to interpret what they saw.
The study found that patients were having trouble generating or using what is known as an “efference copy” – a signal sent from the eye movement system in the brain that indicates the direction and how much the eyes have moved. The efference copy helps validate visual information seen by the eyes. It is believed that the brain of schizophrenia patients fills in the blanks by extrapolating from prior experience, contributing to psychotic symptoms such as hallucinations.
By understanding the cause of these symptoms, Dr. Spering’s vision is to develop a mobile app that patients can use to practice eye movement skills, improving their ability to do common tasks that involve motion perception, such as walking along a crowded sidewalk.
Dr. Spering is now conducting the same experiment on people with Parkinson’s disease. In addition to muscle tremor and stiffness, Parkinson’s patients have poor visual perception and impaired eye movements. Dr. Spering is trying to see if the two are connected; if so, eye movement exercises might improve vision in Parkinson’s patients.
There are also possible applications to enhance performance in sports. Dr. Spering is working with the UBC baseball team to study eye movements and ways increase performance in the field through visual training exercises.
Dr. Spering’s schizophrenia research was published in a recent issue of the Journal of Neuroscience. For the full media release, click here.