From Cognitive Control to Schizophrenia: Key Lessons from Dr. Michael Halassa’s Substack Series

 

In recent years, the conversation around psychiatry and neuroscience has shifted from simple chemical models to circuit-level thinking, and few voices have articulated this transition as clearly as Dr. Michael Halassa. A neuroscientist and psychiatrist at Tufts University, Dr. Halassa has launched a Substack platform where he translates decades of cutting-edge brain research into accessible, conceptually rich essays for clinicians, scientists, and anyone interested in the evolving science of mental health.

His Substack series doesn’t just summarize studies—it reframes how we think about psychiatric illness, especially disorders like schizophrenia. Rather than viewing symptoms in isolation, Halassa emphasizes cognitive control—the brain’s ability to switch tasks, update beliefs, and filter relevant information—as a core functional framework for understanding the roots of mental dysfunction.

One foundational idea explored in the series is the concept of distributed systems in the brain. Michael Halassa likens the mind to a coalition of specialized subsystems—prediction, reward, attention—all working in parallel, and all managed by an "executive control" system. When this executive function breaks down, the result isn’t just noise—it’s dysfunction in perception, motivation, and behavior. This breakdown, he argues, is often central to what we call psychiatric illness.

In the case of schizophrenia, this approach is particularly illuminating. Dr. Michael Halassa points out that symptoms such as hallucinations and delusions may arise from failures in belief updating algorithms—computational processes by which the brain integrates new evidence with prior expectations. Drawing on both human studies and animal models, his essays trace how specific thalamic-prefrontal circuits may govern these updates. When these circuits fail, the brain can’t properly revise its model of reality, leading to persistent false beliefs or sensory distortions.

Through clinical stories—like that of “Jack,” a patient with subtle but debilitating negative symptoms—Halassa shows how even difficult-to-diagnose presentations can be understood as breakdowns in cognitive flexibility and motivation, rooted in circuit-level disruptions. These narratives bring algorithmic psychiatry out of the lab and into the clinic, revealing the human side of a deeply technical field.

Importantly, his Substack is not just a lecture hall; it's a platform for public dissemination of science, aimed at bridging academia and real-world care. For students, clinicians, or curious readers, it’s an evolving curriculum in modern neuroscience. For those in the field, it offers a lens into where psychiatric research is headed: toward precision interventions informed by real biological mechanisms, not just symptom clusters.

Dr. Halassa’s Substack is a valuable resource for those looking to understand the next generation of psychiatric theory and practice. Whether you're interested in the future of pharmacology, the role of computational models in clinical diagnosis, or how the brain’s internal systems harmonize (or don’t), his work offers a grounded yet forward-thinking perspective.

📬 Explore more of Dr. Halassa’s work and subscribe here: https://michaelhalassa.substack.com