Consciousness Club | January 11, 2023

Veith Weilnhammer and The Visual Perception Lab








The Ghost in the Shell

Subjectivity

  • What are the mechanisms of subjective experience?

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 subjective 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

Neural Mechanisms

  • Constructing unambiguous conscious experiences from ambiguous sensory information

Models of Bistability


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

Natural environments

  • One frame predicts the next

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 and likelihood

Computational Psychiatry


  • Are hallucinations caused by weak or strong priors?

Bistable Perception


Computational Psychiatry


Outlook


Outlook


Outlook


Outlook


Summary

Adaptive Perception

  • How to balance internal predictions with external sensory information?

Graded Ambiguity


Perceptual Modes


  • Externally and internally-biased modes of perception

Outlook


  • Confidence Database: 4500 humans, 22 million choices
  • IBL Database: 165 mice, 1.5 million choices

Summary

Thanks a lot for your attention!

Bibliography


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

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

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

Weilnhammer, Chikermane, Sterzer. Bistable perception alternates between internal and external modes of sensory processing. iScience 2021.

Weilnhammer, Stuke, Standvoß, Sterzer. Humans and mice fluctuate between external and internal modes of sensory processing. BioRxiv 2022.