Earlier this month, the 2026 Nobel Prize in Physiology or Medicine shone a light on one of the most transformative tools in modern neuroscience: optogenetics. The brain is home to billions of nerve cells called neurons, and understanding how they communicate with one another is key to understanding how we think, feel, and experience the world. Optogenetics allows researchers to use light to switch selected neurons on or off in a fraction of a second, revealing how those cells contribute to these everyday experiences.
"Optogenetics allows us to study the brain in a way we couldn’t before," says Dr. Caleb Browne, Scientist at the Brain Health Imaging Centre within the Neuroscience Institute at the Centre for Addiction and Mental Health (CAMH). "Previously, we would use electrical manipulation, but because the brain runs on electricity and brain cells use electrical signals to communicate, it made it impossible to differentiate which areas of the brain or individual neurons were contributing to the process we’re trying to study."
"Essentially, optogenetics is allowing us to speak the brain’s language. Unlike electrical stimulation, it allows us to be very precise in selecting which neurons we want to activate or inhibit," explains Dr. Talia Lerner, Scientific Director of Pre-Clinical Neuroscience at CAMH.
An important tool in pre-clinical neuroscience
The unprecedented precision of optogenetics has enabled researchers to answer longstanding theories about how specific circuits and cell types contribute to behaviour, learning, and mental illness. For example, Dr. Browne, who introduced the technique at CAMH, used optogenetics to study serotonin, a neurotransmitter often simplistically described as the brain's "happy chemical".
His research revealed a far more nuanced picture. When serotonin is elevated and released in the brain region where dopamine, another neurotransmitter, is produced, serotonin can actually suppress motivation–our willingness to expend energy pursuing goals. His findings may help explain why increasing serotonin through common antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs) does not always produce straightforward positive effects.
"Optogenetics allowed us to look at the interaction between these two important systems in the brain and figure out what is actually happening," he explains. "This understanding can then help us determine how to better use existing drugs and ultimately improve care for patients."
It highlights why basic science research remains essential to improving mental health care. To design better treatments for mental disorders, we must first have a deep understanding of how the brain functions.
"Tools such as optogenetics show us the foundation of how the brain works. By learning how brain activity is regulated and how it can be disrupted in mental illness, we can identify new ways to develop better treatments," Dr. Browne goes on to explain.
The power of unlikely connections
Part of what makes the optogenetics story so remarkable is that it emerged from discoveries in completely different fields of science.
The idea can be traced back to Nobel Prize-winning scientist Dr. Francis Crick, who proposed that neuroscience needed a way to control neurons with millisecond precision, the timescale on which brain cells communicate. Light would be able to act this fast, but no one knew how light could be used to manipulate neurons.
Algae provided the unexpected solution. Biologists studying algae discovered light-sensitive proteins that help the organism move toward light for photosynthesis. The same protein could be introduced into neurons, making them light-responsive. The story illustrates an important reality of scientific discovery: transformative breakthroughs often emerge when knowledge from entirely different disciplines collides.
Building a leading neuroscience community under one roof
The same idea underpins the new Temerty Discovery Centre, set to open in late 2027. For the first time, research, education, and care will be brought together on one CAMH campus. Its intentionally open and collaborative spaces are designed to connect people, expertise, and ideas, creating new opportunities for discovery.
For CAMH's neuroscience researchers, the building represents so much more than simply new laboratory space. It reflects a commitment to advancing pre-clinical neuroscience and answering some of the most fundamental questions about how the brain works. Researchers will have access to shared infrastructure, cutting-edge technologies, and expanded capacity for approaches such as optogenetics and advanced brain imaging, while working alongside colleagues who have traditionally worked in separate areas, fostering the kind of cross-disciplinary collaboration that increasingly drives breakthroughs.
By creating opportunities for researchers to share ideas, techniques, and expertise, the Temerty Discovery Centre will help strengthen what Dr. Lerner describes as a “back and forth conversation” between basic science and clinical care, connect cutting-edge neuroscience with one of the world's leading mental health hospitals and ultimately accelerating the translation of discoveries that will improve patient care. Dr. Lerner was recently recruited to CAMH from Northwestern University to lead pre-clinical neuroscience at the Temerty Discovery Center. Having trained under one of the 2026 Nobel recipients, Dr. Karl Deisseroth, she is bringing extensive expertise in the monitoring and manipulation of brain circuits to CAMH.
"The brain is really the last frontier of our understanding," says Dr. Browne. "Tools like optogenetics are giving us an unprecedented ability to study specific cells, circuits and neurotransmitter systems, but every new discovery reveals just how much complexity remains. The more we learn, the more questions we uncover. That's what makes this such an exciting time for neuroscience, and why there's still so much left to discover."