Canada Research Chair discovers how the brain remembers visual targets relative to other visible landmarks. This work could help those with brain damage.
Doug Crawford, scientific director of VISTA (Vision: Science to Applications), Distinguished Research Professor and the current Tier 1 Canada Research Chair in Visual-Motor Neuroscience, has devoted his career to understanding how the brain uses vision to plan movement. His work at the York Centre for Vision Research (CVR) ̶ a global leader in this rapidly evolving field ̶ has focused on the control of visual gaze in 3D space, eye-hand coordination and spatial memory during eye movements. This kind of cutting-edge research could lead to the development of devices capable of restoring vision or mobility.
"VISTA is developing technologies that will keep Canadian industry on the cutting edge while also helping people with vision-related problems. It’s the economic and health benefits of those applications that people will feel in their everyday lives."
Crawford’s latest research with former York graduate student Ying Chen, funded by the Canadian Institutes of Health Research (CIHR) and published in Frontiers in Systems Neuroscience (2017), suggests that targeting gaze relative to a visual landmark is different from simply gazing from memory. He sits down with Brainstorm to explain the significance and impact of this research.
Q: What were the objectives of this research, just published in Frontiers in Systems Neuroscience?
A: We were trying to determine what brain areas are active when you remember the location of an object relative to some other visual landmark, and then look that way with your eyes, as opposed to simply looking where you remember the object to be, relative to your own person. In scientific terms, this is called allocentric versus egocentric coding.
Q: How did you go about conducting this research?
A: We put people inside of a magnetic resonance imaging (MRI) magnet, showed them visual stimuli in the dark and measured their eye movements. In the allocentric task, we asked people either to remember the location of a visual stimulus relative to another landmark, which we shifted before asking them to move their eyes; whereas in the egocentric task we asked them to remember where they saw it independent of the landmark.
Later, we analyzed the data to see which brain areas were activated, and which were sensitive to object location relative to the landmark.
Q: What did you find, and did anything surprise you about the key findings?
A: As we expected, both tasks activated areas of the brain involved in eye movements, but the allocentric task, where people used the landmark, produced more memory activation in the ventral stream of vision ̶ areas running along the back and bottom of the brain. The egocentric task, where people just remembered where they saw the target, produced more dorsal stream activation at the back top of brain.
One thing we didn’t expect was that the ventral stream areas continued to be involved in coding direction during the eye movement in the allocentric task. This is something that one doesn’t ordinarily see in standard eye movement tasks.
Q: What are the implications and/or practical applications of this research?
A: One motivation for this line of research is to understand how the brain has different ways of doing things, but that this may rely on different brain areas. This is relevant for people with brain damage because it means that when one function is lost, some other brain area might replace that function.
So in this example, if brain damage affects the way people perceive or remember things using egocentric mechanisms, then these patients might train their brain to rely more on allocentric mechanisms. Knowing how these different functions relate to different brain areas can help to understand patient’s deficits and how to address them.
Q: How would you characterize the impact of this work?
A: The immediate impact is for understanding how the brain works through fundamental, discovery science. Even though various studies have shown that fundamental science has more long-term impact than applied research, it’s often hard to predict what that impact will be.
In this case, I plan to work with some of my clinical collaborators to make sure that this work gets applied for the benefit of patients with brain damage in the coming years. But my work also gets cited by people working on biologically inspired robots. We have a lot of strength in computer vision and robotics right here at York, so this is something I would like to pursue as well.
“I plan to work with some of my clinical collaborators to make sure that this work gets applied for the benefit of patients with brain damage.”
Q: What does this research say about York’s leadership in this area?
A: York’s CVR has often been evaluated as one of the top vision research centres in the world. Our recent success at winning a highly competitive Canada First Research Excellence Fund (CFREF) Grant for our VISTA program signals York’s intend to reach the top of this list, and the Canadian government’s confidence that we can reach that goal.
The current research demonstrates our continued expansion into new areas of interdisciplinary research. We started with visual psychophysics ̶ behavioral tests of vision, then added in computer vision and biological recordings of brain activity. And with the purchase of a research-dedicated MRI, we’ve made our mark in functional brain imaging.
“York’s CVR has been evaluated as one of the top vision research centres in the world. Our recent success at winning a major CFREF Grant for our VISTA program signals York’s intend to reach the top of this list… and the Canadian government’s confidence that we can reach that goal.”
With the new VISTA program, you can expect to see much more leadership in terms of engaging our partners in industry, hospitals and government in this research.
Q: What can you say about the importance of funding this kind of research?
A: It’s important that we explain the benefits of our research to Canadians, for Canada’s wealth and well-being, because we can’t do this vital work without funding, and some of this funding will always have to come from public sources.
VISTA is involved in both fundamental and applied research, and is developing technologies that will keep Canadian industry on the cutting edge while also helping people with vision-related problems. It’s the economic and health benefits of those applications that people will feel in their everyday lives. But it’s the publicly funded fundamental research that feeds this process.
The article, “Cortical activation during landmark-centered vs. gaze-centered memory of saccade targets in the human: An FMRI study,” was published in Frontiers in Systems Neuroscience (2017). To learn more about Crawford’s work, visit his faculty profile, his Visuomotor Neuroscience Lab, the VISTA website or the CVR website.
By Megan Mueller, manager, research communications, Office of the Vice-President Research & Innovation, York University, email@example.com