Human communication

Study examines role of communication defects in psychotic disorders

Communication between brain areas is essential for the brain to correctly process sensory signals and adopt an appropriate behavioral response. Dysfunctions of these communication pathways are likely to be correlated with the onset of schizophrenia. Recent research has demonstrated this phenomenon in humans. The pilot discovery was carried out by a team from the University of Geneva (UNIGE), Switzerland, as part of the Synapsy National Research Pole. Their study, published in the ‘American Journal of Psychiatry’, made it possible to consider a very early diagnosis.

By carrying out analyzes of the brain activity of children, adolescents and young adults at genetic risk of contracting the disease, the research team demonstrated that a decrease in the activation of gamma waves, known to their role in the good transmission of information in the brain, was correlated with the appearance of psychotic symptoms even before the appearance of disorders in their own right. In the mammalian brain, the electrical activity of neurons responds to oscillatory rhythms detectable by electroencephalography. The coordinated activation of these different waves, which governs, for example, the processing of sensory inputs or the consolidation of memories, allows the brain to function correctly. “We suspected that gamma waves, the highest frequency of brain rhythms, play a decisive role in the development of symptoms of schizophrenia,” said Stephan Eliez, professor in the Department of Psychiatry, and Christoph Michel, professor in the Department of basic neuroscience, who co-led the research. “However, we had yet to confirm that this altered synchronization of neuronal communication pathways seen in mice does indeed exist in humans.”

People with a 22q11 chromosome microdeletion have a 25-30% risk of developing schizophrenia in adulthood. “They therefore constitute a particularly relevant at-risk population for studying the cerebral development of this disease”, specifies Valentina Mancini, doctoral student in the laboratory of Stephan Eliez and first author of this study. People with schizophrenia often suffer from a reduced ability to process auditory information; in order to detect any disturbance in brain communication, the scientists therefore measured the activation of gamma waves following an auditory stimulus in 22q11 patients of all ages, compared to people without this microdeletion. “Children and adolescents at genetic risk for schizophrenic disorders but without visible symptoms presented the same patterns of gamma wave disturbance as patients who actually had the disease”, explains Vincent Rochas, scientific collaborator in Christoph Michel’s laboratory. Moreover, a linear growth of gamma band oscillations has been observed in people without a genetic predisposition to schizophrenia, showing a progressive maturation of communication between brain areas during development. “However, this maturation is absent in 22q11 patients, regardless of their age, suggesting an abnormal development of the circuits underlying neuronal oscillations in adolescence”, emphasizes Valentina Mancini.

The research team also identified a strong correlation between the deficit of gamma band activation and the severity of psychotic symptoms, such as auditory hallucinations, thus confirming the existence of a neurobiological progression of the disease. “Our results confirm that this dysfunction appears very early”, underline the authors. “We now want to identify the best moment in the child’s development to intervene in relation to this pathological shift.” Additionally, studies in mice show that targeted neuroleptic treatments are successful in correcting neural dysfunction; moreover, the alterations in the gamma bands identified here could be restored thanks to non-invasive neurostimulation techniques targeting the affected brain regions, thus opening the way to entirely new therapeutic perspectives to treat an often devastating disease. (ANI)

(This story has not been edited by the Devdiscourse team and is auto-generated from a syndicated feed.)