Neurobiologists Uncover Brain Circuits Behind Placebo Pain Relief

Researchers pinpoint key brain regions and endogenous opioid signaling that drive expectancy-based pain reduction

Apr. 17, 2026 at 1:05am

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A bold, abstract painting in earthy tones depicting sweeping geometric shapes, concentric circles, and precise botanical spirals, representing the complex neural pathways and endogenous opioid signaling involved in placebo-induced pain relief.Groundbreaking research uncovers the intricate neural circuitry that enables the brain to generate its own natural painkillers in response to the power of expectation.San Diego Today

A team of researchers led by the University of California San Diego's Matthew Banghart has identified the specific brain circuitry responsible for placebo pain relief. By adapting a human placebo protocol to mice, the scientists were able to detect activity in mouse brain areas corresponding to those previously implicated in human studies, and uncover the essential roles of neural pathways linking the cortex to the brainstem and spinal cord during placebo-induced pain reduction.

Why it matters

Understanding the neurological mechanisms behind placebo effects could lead to new clinical treatments that leverage patients' own expectations and endogenous opioid systems to manage pain without the risks of addictive painkillers. The findings also suggest ways to train people to build preemptive resilience to future pain through placebo conditioning.

The details

The study is the first to establish placebo mechanisms using a 'reverse translation' method, directly adapting a human placebo protocol to mice. The researchers detected opioid peptide signaling in the ventrolateral periaqueductal gray (vlPAG) region of the mouse brain, a hub for pain processing, and found that blocking this opioid activity using a light-activated drug could disrupt both placebo-induced and morphine-induced pain relief. They also discovered that training mice to exhibit a placebo effect with one type of pain produced relief for several different pain types, including injury-induced pain.

  • The study was published in the journal Neuron on April 17, 2026.

The players

Matthew Banghart

An associate professor in the School of Biological Sciences at the University of California San Diego and the lead author of the study.

Janie Chang-Weinberg

A PhD student in the Biological Sciences Graduate Program and a co-first author of the study.

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What they’re saying

“We took a placebo protocol from humans and worked it out in mice, and used that to deconstruct the underlying mechanisms. We went much further than previous studies and pinpointed a site at which endogenous opioid peptides are critical, which previously had not been done.”

— Matthew Banghart, Associate Professor, University of California San Diego

“We essentially trained a mouse brain to create its own broad-spectrum painkillers on demand, precisely where they are needed to treat pain, without the off-target effects of opioid-based painkillers.”

— Janie Chang-Weinberg, PhD Student, Biological Sciences Graduate Program

What’s next

Future studies will explore different placebo training strategies in mice with the goal of developing protocols that can readily translate to produce placebo pain resilience in the general population, especially those living with chronic pain.

The takeaway

This research offers hope of leveraging patients' own expectations and endogenous opioid systems to manage pain without the risks of addictive painkillers, and suggests new ways to train people to build preemptive resilience to future pain through placebo conditioning.