Center-Surround Processing in Psychosis

Area of Science:

• Neuroscience
• Visual Perception
• Psychopathology

Background:

• People with psychotic psychopathology (PwPP) exhibit altered visual perception.
• Contrast surround suppression is a visual illusion where a central pattern's contrast is reduced by a surrounding pattern.
• PwPP typically display weaker contrast surround suppression than controls, but underlying mechanisms remain unclear.

Purpose of the Study:

• Investigate perceptual and neural mechanisms of surround suppression in PwPP and their relatives.
• Examine visual cortex and lateral geniculate nucleus (LGN) responses using fMRI.
• Assess the relationship between surround suppression, GABA levels, and symptom severity.

Main Methods:

• Assessed surround suppression in 38 controls, 44 relatives, and 64 PwPP.
• Quantified contrast discrimination thresholds and 7 tesla fMRI responses in LGN, V1, and LOC.
• Measured occipital GABA concentration using 7 T MR spectroscopy.

Main Results:

• Lateral occipital complex (LOC) showed weaker surround suppression in PwPP and relatives compared to controls.
• No significant group differences in surround suppression strength were observed in V1.
• Behavioral measures and suppression metrics did not correlate with GABA levels or symptom severity.

Conclusions:

• Subtle differences in visual center-surround processing exist in PwPP.
• Discrepancies with prior research may stem from task design and attentional differences.
• Findings highlight the complexity of visual processing alterations in psychotic psychopathology.