Using a specialized magnetic resonance imaging (MRI) sensor, neuroscientists have discovered how dopamine released deep within the brain influences both nearby and distant brain regions.
Dopamine plays many roles in the brain, most notably related to movement, motivation, and reinforcement of behavior. However, until now it has been difficult to study precisely how a flood of dopamine affects neural activity throughout the brain. Using their new technique, the team found that dopamine appears to exert significant effects in two regions of the brain’s cortex, including the motor cortex.
“There has been a lot of work on the immediate cellular consequences of dopamine release, but here what we’re looking at are the consequences of what dopamine is doing on a more brain-wide level,” says the senior author of the study.
The team found that in addition to the motor cortex, the remote brain area most affected by dopamine is the insular cortex. This region is critical for many cognitive functions related to perception of the body’s internal states, including physical and emotional states. The study appears in Nature.
Like other neurotransmitters, dopamine helps neurons to communicate with each other over short distances. Dopamine holds particular interest for neuroscientists because of its role in motivation, addiction, and several neurodegenerative disorders, including Parkinson’s disease. Most of the brain’s dopamine is produced in the midbrain by neurons that connect to the striatum, where the dopamine is released.
For many years, the lab has been developing tools to study how molecular phenomena such as neurotransmitter release affect brain-wide functions. At the molecular scale, existing techniques can reveal how dopamine affects individual cells, and at the scale of the entire brain, functional magnetic resonance imaging (fMRI) can reveal how active a particular brain region is. However, it has been difficult for neuroscientists to determine how single-cell activity and brain-wide function are linked.
“There have been very few brain-wide studies of dopaminergic function or really any neurochemical function, in large part because the tools aren’t there,” the senior author says. “We’re trying to fill in the gaps.”
About 10 years ago, the lab developed MRI sensors that consist of magnetic proteins that can bind to dopamine. When this binding occurs, the sensors’ magnetic interactions with surrounding tissue weaken, dimming the tissue’s MRI signal. This allows researchers to continuously monitor dopamine levels in a specific part of the brain.
In their new study, the authors set out to analyze how dopamine released in the striatum of rats influences neural function both locally and in other brain regions. First, they injected their dopamine sensors into the striatum, which is located deep within the brain and plays an important role in controlling movement. Then they electrically stimulated a part of the brain called the lateral hypothalamus, which is a common experimental technique for rewarding behavior and inducing the brain to produce dopamine.
Then, the researchers used their dopamine sensor to measure dopamine levels throughout the striatum. They also performed traditional fMRI to measure neural activity in each part of the striatum. To their surprise, they found that high dopamine concentrations did not make neurons more active. However, higher dopamine levels did make the neurons remain active for a longer period of time.
“When dopamine was released, there was a longer duration of activity, suggesting a longer response to the reward,” the senior author says. “That may have something to do with how dopamine promotes learning, which is one of its key functions.”
After analyzing dopamine release in the striatum, the researchers set out to determine this dopamine might affect more distant locations in the brain. To do that, they performed traditional fMRI imaging on the brain while also mapping dopamine release in the striatum. “By combining these techniques we could probe these phenomena in a way that hasn’t been done before,” the senior author says.
The regions that showed the biggest surges in activity in response to dopamine were the motor cortex and the insular cortex. If confirmed in additional studies, the findings could help researchers understand the effects of dopamine in the human brain, including its roles in addiction and learning.
“Our results could lead to biomarkers that could be seen in fMRI data, and these correlates of dopaminergic function could be useful for analyzing animal and human fMRI,” the senior author says.
http://news.mit.edu/2020/dopamine-brain-activity-mri-0401
https://www.nature.com/articles/s41586-020-2158-3
How dopamine drives brain activity
- 1,609 views
- Added
Edited
Latest News
Dissection of the schizophr…
By newseditor
Posted 26 May
Protease action on controll…
By newseditor
Posted 25 May
Maternal inflammation activ…
By newseditor
Posted 25 May
How cells deal with extra c…
By newseditor
Posted 25 May
Flicker stimulation modulat…
By newseditor
Posted 25 May
Other Top Stories
Elevated love hormone levels and higher satisfaction with life in y…
Read more
Synthetic red blood cells to carry drugs!
Read more
Why some older adults remember better than others
Read more
Mechanism of sperm maturation!
Read more
Facial and scene recognition areas of brain identified!
Read more
Protocols
Spatially resolved lipidomi…
By newseditor
Posted 24 May
Efficient expansion and CRI…
By newseditor
Posted 21 May
Massively parallel in vivo…
By newseditor
Posted 20 May
Breast cancer-on-chip for p…
By newseditor
Posted 16 May
Methods for making and obse…
By newseditor
Posted 15 May
Publications
Toward an interventional sc…
By newseditor
Posted 26 May
Cryo-EM reveals that iRhom2…
By newseditor
Posted 25 May
Fetal brain response to mat…
By newseditor
Posted 25 May
Children born after assiste…
By newseditor
Posted 25 May
Macrophage-induced integrin…
By newseditor
Posted 25 May
Presentations
Hydrogels in Drug Delivery
By newseditor
Posted 12 Apr
Lipids
By newseditor
Posted 31 Dec
Cell biology of carbohydrat…
By newseditor
Posted 29 Nov
RNA interference (RNAi)
By newseditor
Posted 23 Oct
RNA structure and functions
By newseditor
Posted 19 Oct
Posters
A chemical biology/modular…
By newseditor
Posted 22 Aug
Single-molecule covalent ma…
By newseditor
Posted 04 Jul
ASCO-2020-HEALTH SERVICES R…
By newseditor
Posted 23 Mar
ASCO-2020-HEAD AND NECK CANCER
By newseditor
Posted 23 Mar
ASCO-2020-GENITOURINARY CAN…
By newseditor
Posted 23 Mar