fMRI brown bag: February 29

Please join us for an fMRI brown bag given by Fan Cheng, a PhD candidate in the Kamitani lab at Kyoto University.

Time: 12:15-1:15pm

Location: Moore Hall, room 110

Toward deciphering neural representations behind visual illusions using reconstruction methods

Abstract: Visual illusions provide significant insights into the brain’s interpretation of the world given sensory inputs. Although physiological and neuroimaging studies have provided evidence of neural responses associated with illusory features, the precise impact of these neural responses on overall perceptual experience remains elusive. In my talk, I will discuss how we tackle this issue by reconstructing illusory percepts as images from brain activity at different levels of processing in the visual cortex. Our approach combines brain decoding techniques with deep neural network (DNN) representations. The reconstruction model was tested on two types of illusions: illusory lines and neon color spreading. The results demonstrate successful reconstructions of visual features not present in the actual sensory inputs, consistent with our subjective experiences. Reconstructions from individual visual areas not only revealed the areas involved in processing illusory features, extending to higher areas within the ventral cortex (a challenge for existing methods), but also unveiled detailed representations of illusions. Taken together, this framework offers a way to materialize subjective mental content into formats amenable to visual interpretation and quantitative analysis, thereby shedding new light on the brain’s internal representations of the world.