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Seeing faces: evidence suggesting cortical disinhibition in the genesis of visual hallucinations.

Giuseppe Iaria¹, Christopher Fox², & Jason Barton³

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1. University of British Columbia, Medicine
2. University of British Columbia, Ophthalmology and Visual Sciences
3. UBC, Neurology and Ophthalmology

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Manuscript

Date:

Received 22 April 2008 19:58 UTC; Posted 22 April 2008

Subjects:

Neuroscience

Tags:

• visual cortex
• Fusiform Gyrus
• Hallucinations
• Faces
• Trees

Abstract:

The neural mechanisms responsible for triggering visual hallucinations are poorly understood. Here, we report a unique patient whose hallucinations consist exclusively of faces, and which could be reliably precipitated by looking at trees. Using functional Magnetic Resonance Imaging (fMRI), we found that, while face hallucinations was associated with increased neural activity in a number of cortical regions, including low-level visual areas, there was significant decreased activity in the right fusiform face area, a region that is empirically defined by increase activity during veridical perception of faces. These findings indicate key differences in how hallucinatory and veridical perceptions lead to the same phenomenological experience of seeing faces, and are consistent with the hypothesis that hallucinations may be generated by decreased inhibitory inputs to key cortical regions, in contrast to the excitatory synaptic inputs underlying veridical perception.

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This document is licensed to the public under the Creative Commons Attribution 3.0 License

How to cite this document:

Iaria, Giuseppe, Fox, Christopher, and Barton, Jason. Seeing faces: evidence suggesting cortical disinhibition in the genesis of visual hallucinations.. Available from Nature Precedings <http://hdl.handle.net/10101/npre.2008.1827.1> (2008)

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