FriSem

Speaker: James Mac Shine, Faculty of Medicine, and Brain and Mind Center, The University of Sydney 

Title: Noradrenergic modulation of brain network topology and energy landscape dynamics mediates conscious resolution of perceptual ambiguity

Abstract: Perception is thought to rely upon evolving activity within a recurrent, distributed thalamocortical network whose interconnections are modulated by bursts of noradrenaline. To test this hypothesis, we leveraged a combination of pupillometry, fMRI and recurrent neural network modelling of an ambiguous figures task. Shifts in the perceptual interpretation of an ambiguous image were associated with peaks in pupil diameter, implicating noradrenergic gain alteration in the perceptual switch. We trained a 40-node recurrent neural network to perform a similar perceptual categorisation task, manipulated the gain of the RNN to mimic the effect of noradrenaline and observed an earlier perceptual shift as a function of heightened gain. We then used a dimensionally-reduced form of the RNNs activity to develop two novel predictions: perceptual switches should occur with peaks in low-dimensional brain state velocity and with flattened energy landscape dynamics. We used whole-brain fMRI data to confirm these predictions. These results confirm the core role of the noradrenergic system in the large-scale network reconfigurations that mediate perception.