Summary: Researchers have identified a rare class of cortical neurons whose overactivity appears to drive schizophrenia-like features in a mouse model, including cognitive deficits and disrupted sleep. Dampening the activity of these neurons restored normal sleep patterns and improved behavior in mice carrying a schizophrenia-linked genetic microdeletion.
The study points to a small, specific population of GABAergic projection neurons as a critical node in how the brain compensates for early developmental disturbances and suggests a developmental window in which targeted intervention might prevent the emergence of cognitive symptoms.
Key Facts
- Overactive neurons: A rare somatostatin-expressing GABAergic projection neuron subtype shows hyperactivity in mice with a schizophrenia-associated mutation, correlating with sleep and cognitive disruptions.
- Chemogenetic rescue: Selective reduction of these neurons’ activity via chemogenetic methods normalized sleep architecture and improved behavior in the animal model.
- Prevention opportunity: The results indicate a late developmental turning point when the brain’s compensatory capacity fails, identifying a potential time window for preventive treatments.
Source: University of Copenhagen
Difficulty completing everyday tasks. Memory lapses. Trouble concentrating.
Cognitive impairment is a persistent and debilitating component of schizophrenia. Beyond hallucinations and delusions, problems with memory, attention, and executive function make daily life challenging for many patients. To address these deficits, researchers at the University of Copenhagen investigated cellular and developmental mechanisms that could explain why symptoms often appear long after the initial developmental insult.
In their new study, the team found that a distinct subtype of cortical GABAergic neurons — identified molecularly as an Sst_Chodl somatostatin-expressing, long-range projecting population — became abnormally active in mice engineered to carry the 15q13.3 microdeletion, a genetic lesion linked to schizophrenia, epilepsy, and autism spectrum disorders in humans. Importantly, when scientists selectively reduced the activity of these neurons, affected mice recovered more normal sleep patterns and showed improvements in behavior.
“Current treatments for cognitive symptoms in disorders such as schizophrenia are limited and often nonspecific,” says Professor Konstantin Khodosevich of the Biotech Research and Innovation Center. “Identifying the precise neuronal populations that drive dysfunction opens the door to therapies that are far more targeted.”
A late developmental turning point
Although genetic and developmental risk factors for schizophrenia act early in life, symptoms typically do not appear until adolescence or young adulthood. The researchers explored why this delay occurs by tracking molecular, cellular, and functional changes from the fetal period through maturation.
According to first author Katarina Dragicevic, the brain can compensate for many developmental perturbations for a long time, preserving function. “We found that dramatic alterations in neuronal behavior and gene expression emerge late in development — around the transition to adolescence — which likely explains the delayed onset of symptoms,” she explains. This late-emerging breakdown of compensatory mechanisms defines a potential window for interventions that could prevent or lessen later impairment.
Sleep as a sensitive readout of circuit dysfunction
The team used sleep patterns as an accessible behavioral marker because sleep disruption is a common and measurable feature of many psychiatric disorders. In mice with the 15q13.3 microdeletion, sleep architecture was disturbed in association with altered activity of deep-layer somatostatin-expressing neurons.
Although these Sst_Chodl cells comprise only a tiny fraction of the cortex’s neuronal population, they exert outsized influence over network dynamics and long-range cortical signaling. Detailed analyses, including single-nucleus transcriptomics, calcium imaging, and patch-clamp recordings, linked molecular expression changes to altered physiology specifically in the Sst_Chodl subtype: overall responsivity in deep-layer Sst neurons was impaired, but Sst_Chodl cells showed increased activity that correlated with behavioral deficits.
A promising, cell-specific treatment target
Using chemogenetic inhibition to transiently suppress Sst_Chodl neuron activity in adult microdeletion mice, the researchers were able to reverse sleep disturbances and improve behavior. These results suggest that precisely targeting a narrowly defined neuronal subtype can restore circuit balance and relieve key symptoms without broadly suppressing cortical activity.
Assistant Professor Navneet A. Vasistha emphasizes the translational potential: “While clinical application will require many additional steps, this work identifies a concrete cellular target and a developmental window where interventions might be most effective. A future therapy could aim to modulate a small, vulnerable population of neurons and thereby reduce cognitive symptoms with fewer side effects.”
Key questions answered
A: It shows that hyperactivity in a tiny, specific population of cortical GABAergic projection neurons correlates with schizophrenia-like sleep and behavioral disturbances in a genetic mouse model, highlighting a precise cellular target for potential therapies.
A: Researchers combined single-nucleus transcriptomics, calcium imaging, electrophysiology, and behavioral monitoring in mice carrying the 15q13.3 microdeletion, and then used chemogenetic tools to reduce activity specifically in the affected neuron subtype.
A: The findings support the idea that narrow, cell-type-specific interventions administered during a vulnerable developmental window could prevent or reduce cognitive and sleep-related symptoms with fewer off-target effects than broad-acting drugs.
About this research news
Author: Anna Ahlbom
Source: University of Copenhagen
Contact: Anna Ahlbom, University of Copenhagen
Image: Image credit to Neuroscience News
Original Research: Open access. “Dysfunction of cortical GABAergic projection neurons as a major hallmark in a model of neuropsychiatric syndrome” by Konstantin Khodosevich et al., published in Neuron.
Abstract
Dysfunction of cortical GABAergic projection neurons as a major hallmark in a model of neuropsychiatric syndrome
Neuropsychiatric disorders have a strong genetic component and are linked to developmental risk factors, yet it remains unclear why symptoms commonly emerge later in life and which neuronal types are most responsible for circuit dysfunction. Using a mouse model of the 15q13.3 microdeletion, the study identified the largest gene expression changes in a somatostatin-expressing Sst_Chodl subtype — long-range GABAergic projection neurons. Although perturbations arise early in development, functional impairments in these neurons manifest only at late maturation. Calcium imaging and patch-clamp recordings revealed widespread responsivity deficits in deep-layer somatostatin neurons, with increased activity specifically in the Sst_Chodl subtype. Patch-seq linked molecular signatures to cellular dysfunction. Microdeletion mice displayed sleep disturbances associated with impaired deep-layer Sst neuron activity, which were rescued by chemogenetic inhibition of Sst_Chodl neurons. These findings spotlight GABAergic projection neurons as vulnerable targets in neuropsychiatric disorders and suggest opportunities for cell-specific intervention.