Insights & Outcomes: Darting eyes, faculty honors, and overgeneralization
This month, Insights & Outcomes begins the academic year with some revelations about certain rapid eye movements, new research on the relationship between substance abuse and the tendency to overgeneralize, and details of a trio of faculty honors.
The (darting) eyes have it
Our eyes are constantly darting from point to point, a trait of the primate visual system called a saccade that allows us to track objects of interest in our environment. Yet these rapid movements don’t cause our vision to be continuously blurred. The reason is that our brains are like a smart cameras: Unlike a typical camera, which will snap blurry photographs if the lens darts back and forth, the modern smart camera prevents a picture from even being taken if the image will be fuzzy. During the rapid movement of the eyes between two points, known as a saccade, the brain momentarily blunts our perception of movement.
This serves an important role: For instance, saccades help a mother chimpanzee keep track of multiple active babies at play, alert to the movement of predators, without being becoming distracted by the effects of nausea.
“When we are glancing back and forth, we see a stable percept,” said Yale’s Anirvan Nandy, assistant professor of neuroscience. “We don’t see the motion blur during eye movements, which we would if our visual system were a passive camera.”
In a new study, a team of Yale neuroscientists led by Nandy and Monika Jadi, assistant professor of psychiatry and neuroscience, set out to discover neural mechanisms behind this reduction in visual sensitivity called saccadic suppression. They focused on a crucial area of the visual cortex called V4, which allows us to recognize complex forms.
They found that the rapid eye movements are accompanied by the activation of inhibitory neurons in the layers of V4 that also receive visual signals. This activation suppresses activity throughout area V4, an equivalent of preventing a picture from being taken in primate visual systems.
Without this suppression, the darting of the eyes would cause disorientation and severe nausea in people and other primates, Nandy said. And while it technically means that animals lose some visual sensitivity, saccadic suppression prevents a disruptive sense of disorientation — which, in the case of the mother chimp, would make her less able to keep her babies safe, Jadi said.
“If we don’t have this suppression then we are subject to incorrect judgments about the outside world,” she said.
Nandy and Jadi are co-senior authors of the paper published in the journal Cell Reports.
Addiction and overgeneralization
People rarely experience the same situations twice. This is why we generalize, by applying knowledge of past events to new ones. Yet, while generalizations are a crucial tool in navigating life, overgeneralization can provoke crippling fear in those with anxiety who tend to link a new experience with one that even vaguely resembles a past traumatic event.
For a new study, a group of Yale researchers, led by Elizabeth Goldfarb, assistant professor of psychiatry and of psychology, wanted to know if a tendency to overgeneralize might also characterize substance abuse as well. To better understand this, they taught a game to two groups of people in an online experiment: One group was composed of people who met the National Institute of Alcohol Abuse and Alcoholism’s (NIAAA) definition of risky drinkers and the other did not. Each player was told which cards would win them tokens. Some tokens showed pictures of alcohol, while others did not. Then, players were then asked which cards they would like to play with.
After learning to associate cards with alcohol- and non-alcohol-related outcomes, riskier drinkers were more likely to play with cards that even remotely resembled the one paired with alcohol tokens, showing that they generalized alcohol associations more broadly. When they changed the game and the same cards were associated with “penalty” tokens, the risky drinkers again were more likely to generalize alcohol associations more broadly.
“Our findings show that this process of overgeneralization, which is known to play a role in anxiety, is also relevant in substance use, with risky drinkers showing a tendency to overgeneralize associations with alcohol, leading them to seek out situations that are similar to those which they previously associated with reward and alcohol,” said Goldfarb, who is a professor at Yale School of Medicine and the Faculty of Arts and Sciences.
Goldfarb notes that patients can relapse and feel cravings when placed in a situation that vaguely reminds them of having used alcohol before — in essence they overgeneralize much like people with anxiety do. Yale’s Sanghoon Kang, Grace Larrabee, and Sanya Nair are co-authors of the study, which was published in the journal Psychological Science. The research was funded by the NIAAA and Yale’s Center for the Translational Neuroscience of Alcohol (CTNA).
Postdoctoral Mentoring Prize to Carlson, Rutherford
Professors John Carlson and Helena Rutherford have been awarded Yale’s 2023 Postdoctoral Mentoring Prize.
Carlson, Eugene Higgins Professor of Molecular, Cellular, and Developmental Biology, and Rutherford, associate professor in the Child Study Center, were each recognized as “a faculty member who exemplifies the role of a mentor and who has provided exceptional mentoring to one or more postdoctoral scholars during the previous year.”
Nominees are identified by current postdocs.
“Postdocs are important contributors to the university’s education and research mission and having a supportive and effective faculty mentor is vital for their success at Yale,” said Erin Heckler, associate provost for postdoctoral affairs. “This year, the Yale Postdoctoral Association’s Mentoring Committee and the Office for Postdoctoral Affairs received 23 excellent nominations for faculty mentors. In their nominating letters, professors Carlson and Rutherford stood out for their robust commitment as holistic mentors who support their postdoc mentees’ career and professional development as independent researchers.”
Barron’s contributions to information theory
Andrew Barron, the Charles C. and Dorothea S. Dilley Professor of Statistics and Data Science in the Faculty of Arts and Sciences, recently won the 2024 Claude E. Shannon Award for consistent and profound contributions to the field of information theory.
Barron joined the Yale faculty in 1992 and has written or co-written more than 80 peer-reviewed publications, book chapters, and publications in conference proceedings. He holds multiple patents for his discoveries and is a former chair of the Department of Statistics.
The Shannon Award, first presented in 1974, is the highest honor given by the IEEE Information Theory Society. The organization is the premier professional society dedicated to advancing the mathematical underpinnings of information technology for the benefit of humanity. Information theory encompasses the processing, transmission, storage, and use of information, and the foundations of the communication process.
Barron will deliver his Shannon Award lecture at the IEEE International Symposium in Information Theory in Athens next July.