Study links visual perception deficits in psychosis to altered brain connectivity

New research published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging sheds light on how psychotic disorders, such as schizophrenia, affect the brain’s ability to perceive and process visual information. The study found that individuals with psychotic psychopathology struggle with a visual task that involves identifying patterns amidst noise—akin to a “connect-the-dots” challenge. These perceptual difficulties appear to stem from altered brain activity and impaired connectivity between key visual regions.

Visual perception is a fundamental aspect of daily life, allowing us to recognize objects, navigate our environment, and interpret social cues. Previous studies have documented atypical visual processing in schizophrenia, with impairments in areas like motion detection, contrast sensitivity, and facial recognition. These deficits are not just nuisances—they are linked to the severity of psychotic symptoms and disorganized thinking.

The current study aimed to deepen our understanding of one specific visual function, called contour integration. This process enables the brain to connect spatially separated elements into a unified whole, helping us discern shapes and objects from noisy backgrounds. The researchers sought to uncover how contour integration differs among individuals with psychotic disorders, their biological relatives, and healthy controls, using both behavioral tasks and advanced ultra-high-field brain imaging.

“The biological basis of psychotic disorders, such as schizophrenia, remains poorly understood. By studying the visual system in people with psychosis, we hope to learn more about how brain functions differ in this group, as we have a reasonably good understanding of how brain activity contributes to visual perception in humans (without psychosis) and other animals,” explained study author Michael-Paul Schallmo, an assistant professor of psychiatry and behavioral sciences at the University of Minnesota, Minneapolis.

For their study, the researchers recruited a total of 141 participants: 63 individuals with psychotic psychopathology, 44 biological relatives of individuals with psychosis, and 34 healthy controls. The psychosis group included participants with schizophrenia, bipolar disorder, and schizoaffective disorder, while the relatives group consisted of first-degree family members without a personal history of psychosis. All participants were screened to ensure normal or corrected-to-normal vision and the absence of neurological conditions.

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Participants completed a contour integration task that involved determining the orientation of an egg-shaped contour formed by small visual elements called Gabor patches. The task featured three levels of difficulty: in the easiest condition, contours were presented without background elements, making them simple to discern; in the moderate condition, contours were embedded within a grid of background elements, requiring participants to distinguish the shape from visual noise; and in the most challenging condition, the alignment of the contour elements was deliberately disrupted, creating “jittered” patterns to assess the maximum level of distortion participants could tolerate while still identifying the shape accurately.

The psychosis group performed significantly worse than both the healthy controls and the relatives on the contour integration task, particularly in conditions with background noise or higher levels of jitter. Their lower accuracy indicated a reduced ability to integrate visual elements into coherent shapes. In contrast, the relatives group performed similarly to the healthy controls, suggesting that genetic liability alone does not necessarily impair contour integration.

In addition to this behavioral testing, the participants underwent ultra-high-field functional MRI scans. The researchers focused on brain regions involved in visual processing, including the primary visual cortex, lateral occipital complex, and lateral geniculate nucleus, to study how these areas interact during the contour integration tasks.

Imaging results revealed altered patterns of activity in key visual areas among individuals with psychosis. While activity in the primary visual cortex was largely similar across groups, differences emerged in the lateral occipital complex. Participants with psychosis exhibited heightened activity in this region when processing patterns with background noise. This overactivation may contribute to their struggles with figure-ground segmentation, the ability to distinguish objects from their backgrounds.

The lateral geniculate nucleus also showed differences across groups. Functional connectivity between the lateral geniculate nucleus and primary visual cortex was weaker in individuals with psychosis, particularly when background noise was present. This reduced connectivity suggests that disrupted communication between these regions impairs the brain’s ability to process visual information effectively.

The researchers also observed notable differences in functional connectivity between visual regions. Control participants exhibited strong connectivity between the lateral geniculate nucleus and primary visual cortex, particularly when background noise was present. But this connectivity was reduced in the psychosis group.

Functional connectivity between the primary visual cortex and the lateral occipital complex was also disrupted in psychosis. Participants with psychosis showed less modulation of this connectivity when background noise was introduced, suggesting difficulties in distinguishing shapes from noise.

“During a visual ‘connect the dots’ task, we saw differences in both task performance and brain activity within visual areas in people with psychosis compared with controls,” Schallmo told PsyPost. “Our results suggest this difference in perception may be linked to impaired functioning in other cognitive domains, and may be related to altered patterns of brain activity between visual brain areas.”

Interestingly, while the relatives performed similarly to controls on the behavioral tasks, their brain activity and connectivity patterns resembled those of the psychosis group. This suggests that altered neural processing in visual regions may reflect genetic risk for psychosis, even in the absence of clinical symptoms.

Future research could expand on this study in several meaningful ways to deepen our understanding of visual processing deficits in psychotic disorders. One promising direction is to explore how these impairments evolve over time, particularly during critical phases such as the early stages of illness, acute episodes, or periods of remission. Longitudinal studies could help determine whether these deficits remain stable, worsen, or improve with treatment.

Additionally, larger sample sizes that focus on distinct diagnostic groups, such as schizophrenia, bipolar disorder, or schizoaffective disorder, could clarify whether contour integration deficits are specific to certain conditions or represent a shared characteristic across psychotic disorders. This could help refine diagnostic tools and tailor interventions to the unique cognitive profiles of each disorder.

The study, “Impaired contour object perception in psychosis,” was authored by Rohit S. Kamath, Kimberly B. Weldon, Hannah R. Moser, Samantha Montoya, Kamar S. Abdullahi, Philip C. Burton, Scott R. Sponheim, Cheryl A. Olman, and Michael-Paul Schallmo.