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Positive Symptoms Schizophrenia: Hallucinations and Delusions01:26

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Schizophrenia is a complex psychiatric disorder characterized by a range of symptoms that significantly impact cognition, behavior, and emotional regulation. Among these, the positive symptoms stand out as they involve the addition or exaggeration of normal mental functions, deviating markedly from typical behavior and perception. Hallucinations and delusions are prominent positive symptoms, each profoundly affecting the individual's experience of reality.
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Hallucinations as top-down effects on perception.

Albert R Powers1, Megan Kelley1, Philip R Corlett1

  • 1Department of Psychiatry, Yale University.

Biological Psychiatry. Cognitive Neuroscience and Neuroimaging
|June 20, 2017
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Summary
This summary is machine-generated.

This study explores how the brain integrates information hierarchically. It proposes that hallucinations may arise from aberrant top-down predictive coding in perception.

Keywords:
ConnectivityHallucinationsModularityNeuroimagingNeuropsychologyPredictive CodingPsychosis

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Area of Science:

  • Cognitive Neuroscience
  • Cognitive Neuropsychiatry
  • Computational Neuroimaging

Background:

  • A central debate in cognitive neuroscience concerns information integration across hierarchical brain networks.
  • The concept of 'cognitive penetration' challenges strictly modular views of mental organization.
  • Evidence for and against top-down influences in perception remains contested within cognitive science.

Purpose of the Study:

  • To review the evidence supporting and refuting top-down influences in perceptual processes.
  • To examine cognitive penetration through the lens of a predictive coding model of perception.
  • To propose a framework for understanding altered perceptual processes in mental illness, specifically hallucinations.

Main Methods:

  • Comprehensive review of existing literature on top-down influences in perception.
  • Integration of findings with a predictive coding framework for perception.
  • Application of computational neuroimaging literature to support theoretical arguments.

Main Results:

  • Evidence suggests that higher-level cognition can indeed influence perceptual processes in a 'top-down' manner.
  • A predictive coding model offers a viable mechanism for understanding these top-down effects.
  • These mechanisms provide a potential explanation for altered perception in psychiatric conditions.

Conclusions:

  • Hallucinations can be conceptualized as top-down effects on perception, driven by faulty perceptual priors.
  • Altered predictive coding mechanisms may underlie perceptual disturbances in mental illness.
  • This perspective reconciles hierarchical processing with cognitive influences on perception.