I received a Talent grant from the
Amsterdam Brain and Cognition centre (ABC).
The project is be hosted by Simon van Gaal at the University of Amsterdam.
We collaborate with Anouk Schrantee at Amsterdam University Medical Centre (AMC)
and Serge Dumoulin and Tomas Knapen at the Spinoza Centre for Neuroimaging in Amsterdam
to investigate biochemical and neural processes underlying conscious perception.
Influential theories of consciousness propose that "recurrent processing", the dynamic information exchange between brain regions, is crucial for consciousness. What is so special about recurrent processing that it should yield conscious perception? In this project we explore the role of recurrent processing in conscious perception by administering Memantine, an uncompetitive NMDA antagonist, to healthy subjects. NMDA receptors are uniquely involved in recurrent but not feedforward processing. Blocking NMDA receptors will therefore interfere directly and specifically with recurrent processing.
We assess the influence of Memantine on basic characteristics of visual responses by measuring population receptive fields using 7T-fMRI. For each voxel we determine the location and shape (e.g. size of center and surround) of the aggregate response selectivity of the neurons in that voxel. Additionally, participants perform psychophysical experiments to test the influence of Memantine on the perception of several visual illusions. As the perception of illusions occurs without direct "bottom-up" support from the stimulus, we hypothesize that hampering recurrent processing reduces illusion-strength and the likelihood that illusions will occur. We also record eye movements during all experiments to assess how these are affected by Memantine and how eye movements influence perception.
By combining pharmacological interventions with state-of-the-art human neuroimaging techniques we aim to directly link the biochemical (neurotransmitters) with the system-level (brain regions) mechanisms underlying conscious perception.