Understanding mental health disorders like schizophrenia and depression better, so we can treat patients suffering from these disorders better, is one of the most important aims of psychological research. However, despite the fact that clinical psychology has a wide range of powerful research methods (Mundorf and co-workers, 2026), research on many mental health disorders has been proven very challenging.
This is evident from the fact that despite decades of research, we still do not fully understand how mental health disorders emerge and how they can be healed. One of the major challenges scientists in clinical psychology face is that the brain is the most important organ for mental health disorders. While other parts of the body also play a role in mental health (think of the brain-gut axis), the brain is central for both their development and their therapy. Unfortunately, the brain is very hard to investigate in science. While there are many non-invasive methods to measure the structure and function of the brain on a higher level, like functional magnetic resonance imaging or electroencephalography, it is more or less impossible to investigate living human brains on a cellular level. This would, however, be critical to get a better understanding of molecular processes in the brain, like how neurotransmitters work in the living brain, which in turn could allow for new insights for psychopharmacological treatment.
A breakthrough in clinical neuroscience
A new study, entitled “Developmental xenocortication using human-derived organoids in mice,” just published in the journal Nature, presents a major breakthrough in clinical neuroscience research (Kaganovsky and co-workers, 2026). What the scientists did sounds like science fiction: Using advanced genetic methods, they created mice in which glutamatergic neurons, a very common type of nerve cell, were completely depleted from the cortex and the hippocampus (a brain region relevant for memory, often affected in Alzheimer’s disease).
They then used human stem cells to create so-called brain organoids, living tissue structures created from human brain cells that were created from stem cells. Organoids are not like a functioning human brain in the sense that they are conscious, but as they are created from real human nerve cells, they can be used to study cellular processes and the effects of substances like medications on such processes. The human brain organoids were then transplanted into the brains of the mice that missed the glutamatergic neurons, creating what the scientists called xenocortical mice (from xeno = “foreign” or “alien” and cortical = “related to the cortex of the brain”).
They showed that the mice had robust growth of different human nerve cell types in the brain after this procedure, and that the human nerve cells integrated into the mouse nervous system. This showed that the procedure was a success. Importantly, the xenocortical mice could move around, showing that their nervous system with the human cells inside worked.
The Takeaway
The study introduced a new method in clinical neuroscience that has the potential to address many of the major challenges in cellular research on mental health disorders. In the future, xenocortical mice will potentially allow for much better research on mental health disorders and their treatment. While ethical issues in using human stem cells need to be carefully considered, the potential to develop better medicine for patients suffering from depression and other severe mental health disorders can potentially lead to huge advances in clinical psychology.