Evidence from pupillometry, fMRI, and RNN modelling shows that gain neuromodulation mediates task-relevant perceptual...

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Perceptual updating is thought to involve network resets.
• These resets may be modulated by neuromodulatory neurotransmitters like noradrenaline.
• This process influences how the brain responds to changing sensory information.

Purpose of the Study:

• To investigate the role of neuromodulation in perceptual updating using large-scale brain analysis.
• To test if bursts of noradrenaline correlate with perceptual shifts in ambiguous figures.
• To computationally model and validate predictions about network dynamics during perceptual switching.

Main Methods:

• Pupillometry and functional magnetic resonance imaging (fMRI) were used to analyze an ambiguous figures task.
• A recurrent neural network (RNN) was trained on a perceptual categorization task to model dynamic gain changes.
• Low-dimensional RNN dynamics were used to derive macroscale predictions for fMRI validation.

Main Results:

• Peaks in pupil diameter, an indicator of neuromodulatory bursts, coincided with perceptual shifts.
• Increased neural gain in the RNN model accelerated perceptual switching during uncertainty.
• fMRI data confirmed predictions of perceptual switches occurring with peaks in brain state velocity and a flattened energy landscape.

Conclusions:

• Neuromodulatory systems, particularly noradrenaline, play a critical role in large-scale network reconfigurations for adaptive perception.
• Pupil diameter serves as a viable indirect measure of phasic neuromodulatory activity.
• Computational modeling and neuroimaging provide converging evidence for the proposed mechanism of perceptual updating.