Summary: Researchers have discovered differences in functional brain connectivity in individuals with and without schizophrenia, shedding light on the neural basis of the disorder.
The brain’s cortex regulates sensory information, and its disorganization can lead to symptoms like loss of executive control in schizophrenia. Through advanced brain imaging and mathematical techniques, the study revealed impairment in the organizational pattern that differentiates visual and sensorimotor pathways in those with schizophrenia.
This impairment was linked to the clinical symptoms of the disease, providing insights into its mechanisms.
Key Facts:
- Schizophrenia may arise from disrupted brain connectivity and functional integration.
- The study found the organizational pattern distinguishing visual and sensorimotor pathways is significantly affected in those with schizophrenia.
- Changes in brain organization may provide critical insights into the progression and mechanisms of schizophrenia.
Source: Elsevier
Schizophrenia, a neurodevelopmental disorder that features psychosis among its symptoms, is thought to arise from disorganization in brain connectivity and functional integration.
Now, a new study in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging finds differences in functional brain connectivity in people with and without psychosis and schizophrenia that could help researchers understand the neural underpinnings of this disease.
The brain’s cortex is organized in a hierarchical fashion, anchored by the sensorimotor cortex at one end and by multimodal association areas at the other, with the task of integrating incoming sensory information with internal and external sensory signals. The loss of executive control in schizophrenia may stem from disruption of this hierarchical signaling.
Alexander Holmes, a PhD candidate at Monash University who led the study, said, “We used brain imaging and novel mathematical techniques to investigate the hierarchical organization of the brains of individuals with early psychosis and established schizophrenia. This organization is important for brain health, as it regulates how we can effectively respond to and process stimuli from the external world.”
The researchers used resting-state functional magnetic resonance imaging (fMRI) to measure gradients, an estimate of inter-regional functional coupling. Previous work had suggested that the primary sensory-fugal gradient was disrupted with schizophrenia, but the current study showed instead that secondary processing of the sensorimotor-visual gradient was affected in people with the disease.
Holmes added, “We found that the organizational pattern that differentiates visual and sensorimotor pathways is significantly impaired in individuals with schizophrenia but not in individuals with early psychosis. We then found that this impairment explains behavioral and clinical symptoms of schizophrenia.
“Our results highlight that changes in brain organization provide valuable insights into the mechanisms of schizophrenia, helping us better understand the disease and how it progresses.”
Cameron Carter, MD, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, said of the work, “These new approaches to test mathematical models of the organization of circuits in the human brain are beginning to reveal the nature of the disruption of neural integration that underlies psychotic symptoms in people with schizophrenia.
“Targeting these changes offers a new approach to how we think about developing treatments for this often difficult to treat illness.”
About this schizophrenia research news
Author: Eileen Leahy
Source: Elsevier
Contact: Eileen Leahy – Elsevier
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Disruptions of Hierarchical Cortical Organization in Early Psychosis and Schizophrenia” by Alexander Holmes et al. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging
Abstract
Disruptions of Hierarchical Cortical Organization in Early Psychosis and Schizophrenia
Background
The cerebral cortex is organised hierarchically along an axis that spans unimodal sensorimotor to transmodal association areas. This hierarchy is often characterized using low-dimensional embeddings, termed gradients, of inter-regional functional coupling estimates measured with resting-state functional magnetic resonance imaging (fMRI). Such analyses may offer insights into the pathophysiology of schizophrenia, which is frequently linked to dysfunctional interactions between association and sensorimotor areas.
Methods
To examine disruptions of hierarchical cortical function across distinct stages of psychosis, we applied diffusion map embedding to two independent fMRI datasets: one comprised 114 patients with early psychosis and 48 controls, and the other comprising 50 patients with established schizophrenia and 121 controls. We then analyzed the primary sensory-fugal and secondary visual-to-sensorimotor gradients of each participant in both datasets.
Results
There were no significant differences in regional gradient scores between patients with early psychosis and controls. Patients with established schizophrenia showed significant differences in the secondary, but not primary, gradient relative to controls. Gradient differences in schizophrenia were characterized by lower within-network dispersion in the Dorsal Attention (pFDR<.001), Visual (pFDR=.003), Frontoparietal (pFDR=.018), and Limbic (pFDR=.020) networks and lower between-network dispersion between the Visual network and other networks (pFDR<.001).
Conclusions
These findings indicate that differences in cortical hierarchical function occur along the secondary visual-to-sensorimotor axis rather than the primary sensory-fugal axis, as previously thought. The absence of differences in early psychosis suggests that visual-sensorimotor abnormalities may emerge as the illness progresses.
