Nav: Home

Brain region central to placebo effect identified

July 18, 2007

Researchers have pinpointed a brain region central to the machinery of the placebo effect--the often controversial phenomenon in which a person's belief in the efficacy of a treatment such as a painkilling drug influences its effect.

The researchers said their findings with human subjects offer the potential of measuring the placebo effect and even modulating it for therapeutic purposes. They also said their findings could enable measurements of brain function that "would help determine dysfunctions in cerebral mechanisms that may impair recovery across a number of conditions."

Jon-Kar Zubieta and colleagues published their findings in the July 19, 2007, issue of the journal Neuron, published by Cell Press.

Their studies concentrated on a brain area known as the nucleus accumbens (NAC), a region deep in the brain, known to play a role in expectation of reward. Earlier studies had hinted at involvement of the NAC in the placebo effect, but the nature of that role was unknown, said the researchers.

In their experiments, the researchers told volunteers that they were testing the effects of a new pain-killing drug and that the subjects might receive the drug or a placebo. However, in the experiments, the researchers gave only a placebo injection of a salt solution. The experiments involved asking the subjects to rate their expectation of the pain-killing effects of the "drug" and also the level of pain relief with or without the "drug" that they felt from a moderately painful injection of salt solution into their jaw muscle.

In one set of experiments, the researchers used a molecular tracer scanning technique known as Positron Emission Spectroscopy to measure release from the NAC of the neurotransmitter dopamine--a chemical trigger of the brain's reward response. They found that the greater subjects' anticipation of the pain-killing benefit of the placebo, the greater the dopamine release from the NAC. Also, subjects who reported greater relief from the placebo when they did experience pain showed greater NAC activity when they received the placebo before the pain.

In separate experiments, the researchers studied whether activation of subjects' NAC during reward processing correlated with the magnitude of their placebo effect. They told subjects to expect monetary rewards of different amounts, as their brains were scanned using functional magnetic resonance imaging. The researchers found that the people who showed greater activation of the NAC during this reward-expectation task also showed a greater anticipation of effectiveness of a placebo.

The researchers concluded that "These findings are consistent with the hypothesis that this system is involved in the encoding of the 'incentive value' of the placebo, possibly acting as a gate or permissive system for the formation of placebo effects."

They wrote that "The placebo effect then emerges as a resiliency mechanism with broad implications that, given its activation of specific circuits and mechanisms, can be both examined and modulated for therapeutic purposes."

-end-

The researchers include David J. Scott, Christine M. Egnatuk, Heng Wang, Robert A., Koeppe, and Jon-Kar Zubieta of The University of Michigan, Ann Arbor; Christian S. Stohler of University of Maryland, Baltimore. This work was supported by grants R01 AT 001415 and R01 DA 016423 to J.K.Z. and R01 DE 15396 to C.S.S.

Scott et al.: "Individual Differences in Reward Responding Explain Placebo-Induced Expectations and Effects." Publishing in Neuron 55, 325-336, July 19, 2007. DOI 10.1016/j.neuron.2007.06.028. www.neuron.org.

Cell Press
Study describes changes to structural brain networks after radiotherapy for brain tumors
Researchers compared the thickness of brain cortex in patients with brain tumors before and after radiation therapy was applied and found significant dose-dependent changes in the structural properties of cortical neural networks, at both the local and global level.
Blue Brain team discovers a multi-dimensional universe in brain networks
Using a sophisticated type of mathematics in a way that it has never been used before in neuroscience, a team from the Blue Brain Project has uncovered a universe of multi-dimensional geometrical structures and spaces within the networks of the brain.
New brain mapping tool produces higher resolution data during brain surgery
Researchers have developed a new device to map the brain during surgery and distinguish between healthy and diseased tissues.
Newborn baby brain scans will help scientists track brain development
Scientists have today published ground-breaking scans of newborn babies' brains which researchers from all over the world can download and use to study how the human brain develops.
New test may quickly identify mild traumatic brain injury with underlying brain damage
A new test using peripheral vision reaction time could lead to earlier diagnosis and more effective treatment of mild traumatic brain injury, often referred to as a concussion.
This is your brain on God: Spiritual experiences activate brain reward circuits
Religious and spiritual experiences activate the brain reward circuits in much the same way as love, sex, gambling, drugs and music, report researchers at the University of Utah School of Medicine.
Brain scientists at TU Dresden examine brain networks during short-term task learning
'Practice makes perfect' is a common saying. We all have experienced that the initially effortful implementation of novel tasks is becoming rapidly easier and more fluent after only a few repetitions.
Balancing time & space in the brain: New model holds promise for predicting brain dynamics
A team of scientists has extended the balanced network model to provide deep and testable predictions linking brain circuits to brain activity.
New view of brain development: Striking differences between adult and newborn mouse brain
Spikes in neuronal activity in young mice do not spur corresponding boosts in blood flow -- a discovery that stands in stark contrast to the adult mouse brain.
Map of teenage brain provides evidence of link between antisocial behavior and brain development
The brains of teenagers with serious antisocial behavior problems differ significantly in structure to those of their peers, providing the clearest evidence to date that their behavior stems from changes in brain development in early life, according to new research led by the University of Cambridge and the University of Southampton, in collaboration with the University of Rome Tor Vergata in Italy.

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.

Now Playing: Radiolab

Truth Trolls
Today, a third story of folks relentlessly searching for the truth. But this time, the truth seekers are an unlikely bunch... internet trolls.


Now Playing: TED Radio Hour

Rethinking School
For most of modern history, humans have placed smaller humans in institutions called schools. But what parts of this model still work? And what must change? This hour, TED speakers rethink education.TED speakers include teacher Tyler DeWitt, social entrepreneur Sal Khan, international education expert Andreas Schleicher, and educator Linda Cliatt-Wayman.