See, Hear, Feel

EP70: Dr. Mel Goodale on the duplex account of high-level vision

July 12, 2023 Professor Christine J Ko, MD/Dr. Mel Goodale Season 1 Episode 70
See, Hear, Feel
EP70: Dr. Mel Goodale on the duplex account of high-level vision
Show Notes Transcript

I initially misinterpreted Dr. Goodale's research on the duplex account of high-level vision (listen to hear how), and yet his insights into visual perception are fascinating. We also touch on gas lighting (not gaslighting) and how that relates to visual perception of form; ultimately, it is humbling to recognize that there is much that physicians don't know (and didn't know) about neuroanatomy, physiology, and pathomechanisms of disease. Dr. Melvyn Alan Goodale, PhD, FRSC, FRS is a Canadian neuroscientist. He is a Distinguished University Professor and the founding Director of the Brain and Mind Institute at the University of Western Ontario. He holds appointments in the Departments of Psychology, Physiology & Pharmacology, and Ophthalmology at Western. Goodale's research focuses on the neural substrates of visual perception and visuomotor control; his research has demonstrated that visual perception is functionally independent of the visual control of action. He developed the “duplex” account of high-level vision with his colleague, David Milner. He was awarded the Donald O. Hebb Distinguished Contribution Award (CSBBCS) in 1999, the Hellmuth Prize for Scientific Achievement (Western) in 2007, and the Richard C. Tees Award for Distinguished Leadership (CSBBCS) in 2008. He is the author of Sight Unseen: An exploration of conscious and unconscious vision, 2nd edition.

[00:00:00] Christine Ko: Welcome back to SEE HEAR FEEL. Today, I am extremely excited to be with Dr. Mel Goodale. Dr. Mel Goodale, PhD, is a Canadian neuroscientist. He's a Distinguished University Professor and the Founding Director of the Brain and Mind Institute at the University of Western Ontario. He holds appointments in the Departments of Psychology, Physiology, and Pharmacology, as well as Ophthalmology at Western. Dr. Goodale's research focuses on the neural substrates of visual perception and visual motor control. His research has demonstrated that visual perception is functionally independent of the visual control of action. He developed the duplex account of high level vision with his colleague David Milner. He was awarded the Donald O. Hebb Distinguished Contribution Award in 1999, the Hellmuth Prize for Scientific Achievement in 2007, and the Richard C. Tees Award for Distinguished Leadership in 2008. He's the author of a book, Sight Unseen, which is a fascinating read and has a subtitle, an Exploration of Conscious and Unconscious Vision, which is in its second edition.

[00:01:08] Welcome to Mel. 

[00:01:09] Mel Goodale: Thank you very much. 

[00:01:10] Christine Ko: First I'd like to ask what got you into visual neuroscience in the first place? 

[00:01:15] Mel Goodale: Yeah. I'm an English immigrant. I came over with my parents to Canada when I was six. It was such a life-changing event. I'd been brought up in London, England, after the war, in a kind of suburban town just outside of London. I lived in an apartment with my parents. And suddenly I was in Calgary, Alberta, living in a house on the edge of the prairie, all kinds of, life around me. I became incredibly intrigued with all of nature in that wonderful environment. At age 17, I was lucky enough to go off to university, and I was determined to become a doctor like you. And much, much happened during that first year. I was a very young 17, and the direction of my life changed enormously. The first thing was I encountered psychology for the first time, particularly the brain basis of behavior and cognition and thinking and so on. I really fell in love with the subject. And the second thing was I discovered the social life of university, and so even though I was an honor student in high school, my grades just went down the toilet, and medical school was increasingly not an option. When I barely finished my first degree, I took what's now called a gap year, where you take a year off and get yourself organized mentally. I went back to England actually, and I traveled around the country taking odd jobs, trying to find myself ostensibly. After many months of living in rather damp apartments with dubious roommates, I decided that maybe it was time to come back to academic life. I had a professor I knew well back in Calgary, who somehow recognized a diamond in the rough, and I wrote to him and asked if there was any possibility with my terrible grades that I could get into grad school, and probably something that wouldn't happen today, but I was able to get into graduate school in Calgary, University of Calgary. And I was assigned to a supervisor, Rod Cooper, who was a student of Donald Hebb. And he was studying vision And so I studied vision, because he was my supervisor, and it was a great match. I really liked the subject, and I've never regretted it. I've enjoyed so much learning about how the visual system works and how it controls our behavior, allows to see the world. So that's really how it started. 

[00:03:32] Christine Ko: Yeah, that's cool because you obviously, from what I've read of your work and speaking to you just a little bit right now, you still really love and are excited by your work. It's interesting to hear how some of that was a little bit of serendipity, to be able to land where you landed. 

[00:03:46] Mel Goodale: I think that's actually something of a lesson for undergraduates. Things can go off in many different directions, and [yes] often people find themselves doing things they never dreamed in a million years and loving it. 

[00:03:58] Christine Ko: I mentioned in the introduction you have the duplex account of high level vision, meaning you've proposed that there are two visual pathways in the brain. One for visual perception and one for the visual control of actions. Can you talk about that a little bit and why we need two systems? 

[00:04:15] Mel Goodale: This story about two visual systems came from a patient that I talked about with David in the book, Sight Unseen. And D, as we called her in the literature, we know her as DF. She had real problems seeing the form of objects. She was fine with color, she was fine with the surface properties of objects, whether they looked like wood or plastic or metal, but she just couldn't tell you the orientation, the shape. One day she was being tested with a pencil. She correctly guessed it was a pencil because it was one of those yellow pencils that has the distinctive glossiness and yellow that you associate with that kind of pencil. But she couldn't tell us what position we were holding it in. She just couldn't tell us. Then she reached out. And lo and behold, she grabbed the pencil properly. So if it was being held vertically, then she rotated her hand in flight to the orientation of the pencil and grabbed it. And if it was horizontal, she rotated her hand horizontally. And then we went on to test that in the lab. And so there was this really sharp dissociation between perception of that form of objects, but she could use their form and orientation and so on to control her hand when she was grasping the objects. That was a big revelation to us. Patients have really revealed so much about these different pathways. Ultimately, everything boils down to action. There is a system dedicated to the interface between us and the world and moving around. And then there is a system which allows us to have a representation of the world that's informed by previous experience and knowledge and so on. The requirements for each of those systems are very different. 

[00:05:55] Christine Ko: How do your ideas about this organization, this sort of duplex model of the visual system relate to consciousness and attention? 

[00:06:05] Mel Goodale: Our conscious visual experience to the world depends upon what we call the vision for perception system, the system that allows us to represent the world. We're not always conscious of what we see but we're certainly conscious of many things that are out there. Consciousness of the visual appearance of objects depends upon this vision for perception system, which is a system that flows from early visual cortex down eventually into the temporal lobe. Structures that are involved in memory, social interaction, emotional behavior, and so on, and also makes contact with frontal lobes that are important for executive decision making and planning and communicating and so on. That ventral stream for perception is necessary for having conscious, visual experience of the world. Now the part of the brain that does the processing for the visual control of action, a pathway that also comes from early visual areas and goes up to the posterior parietal cortex at the top of the brain and makes contact with somatosensory areas, with motor areas, sends projections down to the spine, to the brain stem and spine. Those projections allow us to be conscious of the actions we perform, but never the visual information that's being used to control those actions. The visual part of that control is inaccessible to consciousness. It's just an automatic transformation from the visual information into a series of motor movements. 

[00:07:38] Christine Ko: When I first read about this duplex system that you had proposed, I thought it was analogous to System 1, System 2 processes, metacognition.

[00:07:49] Mel Goodale: It's not related to that at all. It's a very different thing.

[00:07:52] Christine Ko: For thinking, System 1 and System 2 don't localize anywhere in the brain, but there's this fast processing and slow processing, and so I had mistakenly thought, oh this, your work is evidence for I can process visual things very quickly.

[00:08:10] Mel Goodale: The timing issue is complex because there are aspects of the visual control of movement that really require very rapid control. Catching a ball, for example, or trying to swat an insect. So those things are really rapid, where you've got some kind of almost autopilot you're on. Changes in the trajectory of your hand movement happen within 80 to a hundred milliseconds. If, on the other hand, you ask someone, tell me when the target moves. And it moves in exactly the same way as when you were trying to swat it or touch it, what you find is instead of it taking 80 to a hundred milliseconds, It takes something like 400 milliseconds to get the the comment out there. It takes a very long time. Perception can afford to be slow, whereas action has to be fast. 

[00:09:00] Christine Ko: Oh, it's interesting. So you think visual control of action is actually probably faster? 

[00:09:04] Mel Goodale: Yeah, I do believe it's faster. The visual pathways that actually go from the eye up into the posterior parietal cortex are on neurons that have very fat axons, very fast myelinated axons, the magnocellular system. Whereas both magno and small cell input goes to the perceptual system. So the perceptual system gets a lot of detail that's fairly slow. Which isn't necessary for action: you can work with a rough and ready shape outline. 

[00:09:32] Christine Ko: Yeah. This is from your book, where you make this comment that, "The boundary between perception and knowledge is not a sharp one. Not only does perception inform knowledge, but also knowledge constantly informs perception. We have all experienced perceptual learning. The novice, whether he's a beginner at microscopy, birdwatching, or military surveillance, will literally not see things in the same way as the expert. This use of knowledge to shape our perceptual experience, what we call top-down processing, is a principle used in many machine recognition systems." And you say," In a real sense, what we see in our perceptual experience is determined in large part by what we already know." 

[00:10:11] Mel Goodale: I couldn't have said it better myself. That illustrates a very important thing, that perceptual process depends very much on previous information, previous experience, very top-down controlled. 

[00:10:26] Christine Ko: There's some degree of controversy in dermatopathology where experts can look at the same thing and call it something different, meaning that the diagnosis, the medical diagnosis for the same thing is different, if you show it to one versus another. Going back to your quote from your book, it makes sense because knowledge informs perception, perception informs knowledge. So depending on what school of thought that a given dermatopathologist has been taught in, and what things they've been taught to see and weigh and use, that's probably why we end up at different places. 

[00:11:05] Mel Goodale: My work certainly explains the process, and you've put it very well, that people come through different labs, different traditions, different training regimens, and so therefore they apply what they've learned in the past to interpreting what they see. Absolutely true. I think that happens. It's not unusual. Radiologists that I've talked to, looking at an MRI of a tumor or whatever; clearly experience becomes very important. 

[00:11:30] Christine Ko: Do you have ideas on the implications for these two visual systems in clinic and in rehabilitation? 

[00:11:37] Mel Goodale: Damage to certain parts of the brain results in certain kinds of visual agnosias, prosopagnosia, difficulty in face recognition and so on, versus uh, visual motor control. I'll give you an example that sort of goes back to the 19th century, earliest early 20th century. You may have heard of hysterical blindness, which was very common in places like Vienna, and very Freudian; mostly middle class women who who couldn't see things properly. And then they would throw a ball at them, or they would move their hand rapidly, and suddenly the person would grab it, or push the hand away. What's interesting is it mirrors very much the kind of behavior we saw in DF, in D. And D of course suffered carbon monoxide poisoning. The pathway that serves the form vision area in the brain is quite susceptible to carbon monoxide poisoning. In fact, something like 90% of the cases of visual form agnosia, which is what DF suffers from, is from carbon monoxide poisoning. So now let's go back to Vienna and think about the fact that something that was introduced was gas lighting, and the people who had gas lighting were middle class, and the people who stayed home were women. And, you can well imagine this slow carbon monoxide poisoning that might have been going on. This is conjecture, [right] but might have been going on. In that situation, the physicians, the psychiatrists who dealt with such individuals would have no notion necessarily of the relationship between different brain areas and different aspects of visually guided behavior and visual perception and so on.

[00:13:19] I think there are situations like this where we have to be aware that vision is very complex and that you can have visual information that can be transformed into behavior in some settings with a lesion or a stroke or something of that kind and be completely at loss for another set of behaviors.

[00:13:39] Christine Ko: Wow, that's fascinating. They actually really maybe had a medical problem, but, they're like, you're "hysterical". You're just making it up. Do you have any final thoughts? 

[00:13:48] Mel Goodale: Yeah, a couple of things. One thing I'd like to say is that, first of all, it's been a pleasure to talk to you. And the second thing is I just wanna underline again or underscore again how grateful I and my colleagues in neuropsychology, cognitive neuroscience, are to the many people who sadly have had some kind of brain insult and so on, have devoted so much of their time, and have been so good natured, and allowed us to, to study their deficits and what that can tell us about how the brain works, even though it, it may have absolutely no impact on their condition. I'm very grateful to them, and I don't think they get enough credit. 

[00:14:26] Christine Ko: Yes. Thank you for spending time with me and explaining your work to me, it's been really educational. 

[00:14:32] Mel Goodale: Oh, I've been delighted to talk to you.