Alumni Talk Series: Sven Ohl (Berlin) and Thorsten Kahnt (Chicago)
Sven Ohl was a member of doctoral cohort 2009−2012. He is now a postdoctoral member of Martin Rolfs Emmy Noether Independent Junior Research Group at the Institute of Psychology at Humboldt-Universitaet zu Berlin. Sven will speak about „The impact of eye movements on vision and memory”. Abstract: A vast amount of information enters the visual system with each new fixation, but only a small part of it is consciously perceived and stored in visual memory. Cueing of attention selectively prioritizes information over another – however, it is unclear how selection is realized in the absence of informative cues. In this talk I will present a series of experiments demonstrating that saccades serve as a fundamental and ecologically relevant selection mechanism for vision and memory that is effective in the absence of informative cues. In a second part, I will address the question of whether physiological signals influence the generation of eye movements and show that ongoing heartbeat is coupled to the generation of microsaccades. These findings together highlight an orchestration of mind, actions and body that shape how we perceive and remember the world around us. Thorsten Kahnt was a member of doctoral cohort 2007−2011. After a postdoc in Zurich he became an assistant professor in neurology at the University of Chicago and heads the Kahnt Laboratory (http://labs.feinberg.northwestern.edu/kahnt/). Thorsten will speak about “How the human brain represents future rewards for goal-directed behavior”. Abstract: Decades of research have shown that the orbitofrontal cortex (OFC) plays a key role in goal-directed behavior. However, it is still not entirely clear what computations are carried out within the OFC that make this region so critical for these functions. I will present recent studies from our lab suggesting that the OFC supports goal-directed behavior by signaling expectations about specific outcomes. Our experiments use functional magnetic resonance imaging (fMRI) and food odors, which offer a convenient way to independently manipulate the value and the specific identity of rewards. We analyze fMRI data using pattern-based methods that can detect distributed representations of expected outcomes. Our results demonstrate that the human OFC signals future rewards using both identity-specific and general value codes. Moreover, they reveal how satiety alters OFC representations and enables phenomena like sensory-specific satiety. These findings are in line with recent proposals that the OFC hosts a “cognitive map” of task space, containing the current state of the relevant environment. Such maps could support goal-directed behavior by enabling mental simulations and inferences about the value of unexperienced states and outcomes. All are welcome.
