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| Unraveling Schizophrenia: Insights into Brain Connectivity Disruptions |
Decoding Schizophrenia: Brain Connectivity’s Role
Researchers recently uncovered distinct differences in functional brain connectivity between individuals with and without schizophrenia, shedding crucial light on the neural basis of this complex disorder. The study utilized advanced brain imaging and mathematical techniques to unveil a disruption in the organizational pattern distinguishing visual and sensorimotor pathways in those affected by schizophrenia.
Key Facts:
1. Schizophrenia is associated with disrupted brain connectivity and functional integration.
2. The organizational pattern differentiating visual and sensorimotor pathways is significantly affected in individuals with schizophrenia.
3. Changes in brain organization offer vital insights into the progression and mechanisms of schizophrenia.
Schizophrenia, characterized by psychosis among its symptoms, is believed to arise from disorganization in brain connectivity and functional integration. A recent study published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging has identified differences in functional brain connectivity related to psychosis and schizophrenia. This breakthrough research sheds light on the neural underpinnings of the disease.
The brain’s cortex, organized hierarchically from the sensorimotor cortex to multimodal association areas, plays a pivotal role in integrating sensory information. Disruption of this hierarchical signaling may contribute to the loss of executive control observed in schizophrenia. Alexander Holmes, the lead researcher and a PhD candidate at Monash University, stated, “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 study employed resting-state functional magnetic resonance imaging (fMRI) to measure gradients, providing estimates of inter-regional functional coupling. Contrary to previous assumptions about primary sensory-fugal gradient disruptions in schizophrenia, the research revealed that secondary processing of the sensorimotor-visual gradient is affected in individuals with the disease.
Holmes explained, “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, commended the work, saying, “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.”
Background:
The cerebral cortex is organized hierarchically along an axis spanning from unimodal sensorimotor to transmodal association areas. Low-dimensional embeddings, known as gradients, of inter-regional functional coupling estimates measured with resting-state fMRI characterize this hierarchy. Such analyses may offer insights into the pathophysiology of schizophrenia, frequently linked to dysfunctional interactions between association and sensorimotor areas.
Methods:
To examine disruptions of hierarchical cortical function across distinct stages of psychosis, diffusion map embedding was applied to two independent fMRI datasets. One comprised 114 patients with early psychosis and 48 controls, while the other included 50 patients with established schizophrenia and 121 controls. Primary sensory-fugal and secondary visual-to-sensorimotor gradients of each participant in both datasets were then analyzed.
Results:
No significant differences in regional gradient scores were found between patients with early psychosis and controls. However, patients with established schizophrenia exhibited significant differences in the secondary gradient relative to controls. These differences were characterized by lower within-network dispersion in the Dorsal Attention, Visual, Frontoparietal, and Limbic networks, as well as lower between-network dispersion between the Visual network and other networks.
Conclusions:
These findings suggest 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 implies that visual-sensorimotor abnormalities may emerge as the illness progresses.
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