Montoya Samantha A, Moser Hannah R, Kamath Rohit S, Chong Li Shen, Grant Andrea N, Marjańska Małgorzata, Sponheim Scott R, Engel Stephen A, Olman Cheryl A, Schallmo Michael-Paul
Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN.
Department of Psychiatry and Behavioral Sciences, University of Minnesota, Minneapolis, MN.
medRxiv. 2025 Aug 19:2025.08.15.25333221. doi: 10.1101/2025.08.15.25333221.
People with psychotic psychopathology (PwPP) often experience subtle variations in visual perception, which can be quantified experimentally. In the contrast surround suppression illusion, a central pattern appears to have lower contrast in the presence of a surrounding pattern. PwPP typically show weaker contrast suppression from the surround than controls, but the mechanisms underlying this difference are still poorly understood.
We assessed perceptual and neural surround suppression in 38 controls, 44 first-degree biological relatives of PwPP, and 64 PwPP as part of the Psychosis Human Connectome Project. To better understand neural mechanisms contributing to diminished surround suppression we quantified contrast discrimination thresholds and examined 7 tesla fMRI responses in the lateral geniculate nucleus (LGN), primary visual cortex (V1), and lateral occipital complex (LOC). Additionally, we measured the concentration of γ-aminobutyric acid (GABA; an inhibitory neurotransmitter) in occipital cortex using 7 T MR spectroscopy.
Responses in LOC showed the expected effect of weaker surround suppression in PwPP and relatives versus controls. However, in V1 we found no differences in surround suppression strength between controls, relatives, and PwPP. Additionally, we saw no behavioral evidence for reduced surround suppression in PwPP. Suppression metrics were not significantly correlated with occipital GABA levels or symptom measures. Multi-voxel pattern analysis of V1 fMRI responses revealed a group difference in decoding Surround vs. No Surround, with a trend toward lower accuracy in PwPP vs. controls.
Our results suggest subtle differences in visual center-surround processing among people with schizophrenia. Possible explanations for the discrepancy with previous findings include differences in task design and the deployment of spatial attention across groups. Poorer decoding of center vs. surround may suggest neural representations of spatial context in V1 are less reliable in PwPP.
患有精神病性精神病理学的人（PwPP）常常经历视觉感知的细微变化，这些变化可以通过实验进行量化。在对比度周边抑制错觉中，中央图案在存在周边图案时似乎具有较低的对比度。PwPP通常表现出比对照组更弱的周边对比度抑制，但这种差异背后的机制仍知之甚少。
作为精神病人类连接组项目的一部分，我们评估了38名对照组、44名PwPP的一级生物学亲属和64名PwPP的感知和神经周边抑制。为了更好地理解导致周边抑制减弱的神经机制，我们量化了对比度辨别阈值，并检查了外侧膝状体（LGN）、初级视觉皮层（V1）和枕外侧复合体（LOC）中的7特斯拉功能磁共振成像（fMRI）反应。此外，我们使用7T磁共振波谱测量了枕叶皮层中γ-氨基丁酸（GABA；一种抑制性神经递质）的浓度。
LOC中的反应显示出预期的效果，即PwPP及其亲属与对照组相比，周边抑制较弱。然而，在V1中，我们发现对照组、亲属和PwPP之间在周边抑制强度上没有差异。此外，我们没有发现PwPP中周边抑制减弱的行为证据。抑制指标与枕叶GABA水平或症状测量值没有显著相关性。对V1 fMRI反应的多体素模式分析揭示了在解码周边与无周边时的组间差异，PwPP与对照组相比有准确性较低的趋势。
我们的结果表明精神分裂症患者在视觉中心-周边处理方面存在细微差异。与先前研究结果不一致的可能解释包括任务设计的差异以及各组之间空间注意力的分配。中心与周边的解码较差可能表明PwPP中V1的空间背景神经表征不太可靠。
