New findings published in the journal Nature Neuroscience have shed light on a mysterious pathway between the reward center of the brain that is key to how we form habits, known as the basal ganglia, and another anatomically distinct region where nearly three-quarters of the brain’s neurons reside and assist in motor learning, known as the cerebellum.
Researchers say the connection between the two regions potentially changes our fundamental view of how the brain processes voluntary movements and conditioned learning, and may lend fresh insight into the neural mechanisms underlying addiction and neurodegenerative diseases like Parkinson’s.
“We are exploring a direct communication between two major components of our brain’s movement system, which is absent from neuroscience textbooks. These systems are traditionally thought to function independently,” said the senior author.
“This pathway is physiologically functional and potentially affects our behaviors every day.”
While both subcortical structures have long been known for their separate roles in coordinating movement through the cerebral cortex, they are also critical to both conditioned and error-correction learning.
The basal ganglia, a group of midbrain nuclei which the author describes as the “brain’s go-no-go system” for determining whether we initiate or suppress movement, is also involved in reward-based learning of behavior triggered by the release of dopamine.
“It’s the learning system that promotes motivated behavior, like studying for a good grade. It’s also hijacked in cases of addiction,” said a co-author of the study. “On the other hand, every behavior that we learn — whether it’s to hit a baseball or play violin — this motor learning is happening in your cerebellum at the back of the brain. It’s your brain’s optimization machine.”
However, the team’s latest research suggests the cerebellum could be involved in both.
In their study, the researchers say they have reported the first direct evidence that the two systems are intertwined — showing the cerebellum modulates basal ganglia dopamine levels that influence movement initiation, vigor of movement and reward processing.
“This connection starts at the cerebellum and goes to neurons in the midbrain that provide dopamine to the basal ganglia, called the substantia nigra pars compacta. …. We have brain recordings showing this signal is strong enough to activate the release of dopamine within the basal ganglia,” explained the author. “This circuit may be playing a role in linking the cerebellum to motor and nonmotor dysfunctions.”
The team is seeking to identify exactly where cerebellar projections to the dopamine system originate at the nuclei level, a key step in learning whether the function of this pathway can be manipulated, the author said.
However, the team’s findings so far could have research implications for neurodegenerative diseases like Parkinson’s, which is associated with the death of dopamine-producing neurons in the substantia nigra.
“This pathway seems very important to our vigor of movement and speed of cognitive processes. Parkinson’s patients not only suffer from suppression of movement, but apathy in some cases,” said the author. “The cerebellum’s location at the back of the brain makes it a much easier target for novel therapeutic techniques, such as non-invasive transmagnetic or direct-current stimulation.
“Since we’ve shown the cerebellum is directly exciting dopamine neurons in the substantia nigra, we might now use mouse models for Parkinson’s to explore such techniques to see if that jumpstarts activity of these neurons and relieves symptoms of the disease.”
https://www.nature.com/articles/s41593-023-01560-9
Latest News
Regular snoring could be ba…
By newseditor
Posted 24 Jun
Circadian rhythm drives the…
By newseditor
Posted 21 Jun
Six distinct types of depre…
By newseditor
Posted 21 Jun
Key role of a growth factor…
By newseditor
Posted 21 Jun
Bidirectional BCI functiona…
By newseditor
Posted 19 Jun
Other Top Stories
Branched-chain amino acids extend life span
Read more
Enzyme replacement therapy prevents vascular calcification
Read more
A redox signalling globin is essential for reproduction in round worms
Read more
How to stay young for longer
Read more
Origami-based scaffolds for tissue repair
Read more
Protocols
Deciphering spatial domains…
By newseditor
Posted 23 Jun
High-throughput volumetric…
By newseditor
Posted 21 Jun
Bioengineered human colon o…
By newseditor
Posted 14 Jun
Development of an efficient…
By newseditor
Posted 12 Jun
A co-culture system of macr…
By newseditor
Posted 10 Jun
Publications
Social Isolation and Loneli…
By newseditor
Posted 24 Jun
Regular snoring is associat…
By newseditor
Posted 24 Jun
Programmed cell death: NINJ…
By newseditor
Posted 22 Jun
Circadian-clock-controlled…
By newseditor
Posted 21 Jun
Personalized brain circuit…
By newseditor
Posted 21 Jun
Presentations
Myelin plasticity in the ve…
By newseditor
Posted 10 Jun
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
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