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Visual mental imagery (VMI) and visual hallucinations (VH) are linked in neurodegenerative and psychiatric conditions. Stronger VMI correlates with increased VH, potentially due to heightened top-down visual processing.

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Area of Science:

  • Neuroscience
  • Psychiatry
  • Cognitive Psychology

Background:

  • Visual mental imagery (VMI) involves internal visualization, while visual hallucinations (VH) are perceptions without external stimuli.
  • Understanding the interplay between VMI and VH is crucial in neurodegenerative and psychiatric disorders.

Purpose of the Study:

  • To review the relationship between VMI and VH in Parkinson's disease (PD), Alzheimer's disease (AD), Dementia with Lewy bodies (DLB), and schizophrenia (SCZ).
  • To explore the neurobiological underpinnings and cognitive factors connecting VMI and VH.

Main Methods:

  • Literature review of studies investigating VMI and VH in specified patient populations.
  • Analysis of neuroimaging findings and cognitive assessments, particularly reality monitoring.

Main Results:

  • A positive association between VMI vividness and VH occurrence was found in PD, AD, and SCZ.
  • Patients with VH in PD and SCZ exhibited reality monitoring deficits.
  • Neuroimaging implicated temporo-occipital regions for both VMI and VH, with additional frontal connectivity issues in SCZ.
  • Individuals experiencing VH generally possess stronger VMI, suggesting dominant top-down processing.

Conclusions:

  • Heightened VMI may predispose individuals to VH, particularly in conditions with disrupted reality monitoring and thought processes.
  • Hyper-functioning of visual associative areas might contribute to vivid internal imagery and subsequent misattribution in psychiatric conditions.