M-BIC Lecture Series: Pieter R. Roelfsema
Head of the Department of Vision & Cognition, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
Feedforward and feedback interactions for visual perception and restoring a rudimentary form of vision in the blind
Most theories hold that early visual cortex is responsible for the local analysis of simple features while cognitive processes take place in higher areas of the parietal and frontal cortex. However, these theories are not undisputed because there are findings that implicate early visual cortex in visual cognition - in tasks where subjects reason about what they see. Are these cognitive effects in early visual cortex an epiphenomenon or are they functionally relevant for these mental operations? I will discuss new evidence supporting the hypothesis that the modulation of activity in early visual areas has a causal role in cognition. I will discuss how the modulation emerges as the interaction between brain areas, with a special role for specific classes of interneurons.
Insights into these interactions between brain regions also inspire new approaches to create a visual prosthesis for the blind, by direct interfacing with the visual cortex. To goal is to directly project images from the outside world onto the cerebral cortex, bypassing malfunctioning eyes. The electrical stimulation of electrodes in the visual cortex leads to artificial percepts called "phosphenes”. Our results show that we can elicit pattern vision by generating patterned stimulation of the visual cortex, in the same way that pixels form recognizable patterns on a screen. We are still in the proof-of-concept phase, but if successful, this research could take an important step in the direction of a visual prostheses for the profoundly blind.