The role of predictive processes in altered states of consciousness

Veith Weilnhammer and The Visual Perception Lab








The Ghost in the Shell

Subjectivity

  • How does subjective experience occur at all?

Neural Mechanisms

  • What are the neural events that generate conscious experience?

Scale

  • What is the scale at which conscious experience emerges from biological activity?

Function

  • What is the evolutionary function of conscious experience?

Detection

  • How can we detect conscious experience outside of the human mind?

5 problems

Mechanisms

Sensory Inputs

Executive Function

Attention

Experimental Dissociation

Sensory Ambiguity

Bistable Perception

Bistable Perception

Bistable Perception

Bistable Perception

Predictive Coding


Predictive Coding


Predictive Coding


Predictive Coding


Predictive Coding


Predictive Coding


Model-based fMRI


  • Prediction errors are encoded in IFC and V5/hMT+.

Model-based fMRI


  • Prediction errors are encoded in IFC and V5/hMT+.

Model-based fMRI


  • Prediction errors are fed forward from V5/hMT+ to IFC.

Model-based fMRI


  • Perceptual content can be decoded from V5/hMT+.

Model-based fMRI


  • Prediction errors are generated in suppressed V5/hMT+ voxels.

Feedforward Processing

  • Suppressed voxels in V5/hMT+ encode perceptual conflict.
  • IFC receives feedforward information about perceptual conflict.

Feedback processing

  • Is the prefrontal representation of perceptual conflict relevant for conscious experience?
  • Causal intervention: theta-burst stimulation in IFC and vertex

TMS

TMS

TMS

TMS

TMS

Hybrid model

  • IFC detects and resolves perceptual conflict during bistable perception.

Summary

Feedforward processing

  • Individual frames are processed independently

Feedforward processing

  • Individual frames are processed independently

Natural environments

  • Individual frames are strongly autocorrelated

Feedback

  • Predictive coding compresses the input and saves energy

Feedback

  • There is extensive feedback connectivity within the brain

Circularity

  • The balance between predictions and prediction errors needs to be regulated

Hallucinations

Computational Psychiatry


  • Imbalance between in the precision-weighting of prior an likelihood

Computational Psychiatry


  • Weak vs. strong priors: Corlett et al. (TICS 2019); Sterzer et al. (Biol. Psych. 2018)

Bistable Perception


Computational Psychiatry


Outlook


Outlook


Outlook


Outlook


Summary

Thanks a lot for your attention!

Bibliography


Weilnhammer, Fritsch, Chikermane, Eckert, Kathak, Stuke, Sterzer. An Active Role of Inferior Frontal Cortex in Conscious Experience. Current Biology 2021.

Weilnhammer, Lukas, Eckert, Stuke, Heinz, Sterzer. Psychotic Experiences in Schizophrenia and Sensitivity to Sensory Evidence. Schizophrenia Bulletin 2020.

Weilnhammer, Stuke, Sterzer, Schmack. Hierarchical Predictions for Perceptual Decisions. Journal of Neuroscience 2018.

Weilnhammer, Stuke, Hesselmann, Sterzer, Schmack. A Predictive Coding Account of Bistable Perception. PLOS Computational Biology 2017.

Schmack, Weilnhammer, Heinzle, Stephan, Sterzer. Learning what to See in a Changing World. Frontiers in Humans Neurocience 2016.