summary: Dopamine neurons connect sub-regions of the striatum that contribute to habit formation. The findings shed new light on how habits are formed, and how they can be broken.
Source: Northwestern University
According to a study published in Northwestern Medicine, scientists have uncovered how dopamine links the sub-regions of the striatum necessary for habit-forming. cell reportFindings that can change the overall understanding of habit formation—and they can be broken.
“Circuits are going both ways, and so maybe this gives a possible idea of how to break a bad habit if there is a circuit that allows information flow to go the other way,” says Talia Lerner, PhD, neuroscience said assistant professor of and senior author of the study.
The basal ganglia are a group of nuclei beneath the cerebral cortex, which operate primarily in closed parallel loops. These loops, or circuits, arise from different regions of the dorsal striatum, including an associative circuit controlling goal-directed behavior from the dorsomedial striatum and a somatosensory circuit controlling habit formation from the dorsal striatum.
In addition to closed loops, it has long been speculated that there is an open “ascending spiral” loop that allows goal-directed behavior to become a habit.
Lerner and his team set out to investigate the “ascending spiral hypothesis.” In this circuit, signals in the dorsomedial striatum travel to another brain region, called the substantia nigra, which contains most of the brain’s dopamine neurons. The signals were hypothesized to make dopamine neurons fire and cause the release of dopamine in the dorsolateral striatum. This type of dopamine release is needed to form a habit.
Although the ascending spiral hypothesis was developed 20 years ago, it has been difficult to test. Using new transsynaptic and interspecific genetic tools, the scientists were able to complete a careful investigation.
“The exciting thing in this study is that we were able to use the new tool to detect both forward circuits and backward circuits and actually test whether synaptic connections are where we think they should be and if They work the way we think they should,” Lerner said.
The evidence they found for the ascending spiral hypothesis was mixed.
“The ascending spiral is there, however, it doesn’t work the way it was envisioned,” said Northwestern University’s Interdepartmental Neuroscience (NUIN) PhD student Priscilla Ambrosi. program and lead author of the study.
In addition to discovering new details about how the ascending spiral circuit might work, the authors also found evidence for a “descending spiral,” potentially conveying habit-related information from goal-directed subregions of the striatum to other directions. will transmit.
“People didn’t really think this ‘descending’ spiral existed, but we found that it does and there’s actually equivalent evidence for it compared to an ascending spiral,” Lerner said.
“Now, we need to find out how exactly these ascending and descending circuits work. We are interested in the idea that they receive and perhaps control information from other places in the brain during habit formation. Different synapses get stronger or weaker,” Lerner said.
About this dopamine research news
Author: Melissa Rohman
Source: Northwestern University
contact: Melissa Rohman – Northwestern University
image: Image is in public domain
Basic Research: open access.
“Stratonigrostriatal Circuit Architecture for Disruption of Dopamine Signaling” by Priscilla Ambrosi et al. cell report
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essence
Straitonigrostriatal circuit architecture for the disruption of dopamine signaling
Highlight
- Transsynaptic and Interfacial Genetic Tools for Studying Stratonigrostrial Circuits
- Closed-loop striatonigostriatal circuits may regulate dopamine neuron firing
- An open-loop “ascending spiral” circuit exists but does not control firing
- An open-loop “descending spiral” circuit also exists, but does not control firing.
summary
The basal ganglia operate in largely closed parallel loops, including an associative circuit for goal-directed behavior originating from the dorsomedial striatum (DMS) and a somatosensory circuit critical for habit formation originating from the dorsolateral striatum (DLS).
An exception to this parallel circuit organization has been proposed to explain how information can be transferred between striatal subregions, for example, from DMS to DLS during habit formation. The “ascending spiral hypothesis” proposes that DMS inhibit dopamine signaling in the DLS through a tri-synaptic, open-loop striatonigrostrial circuit.
Here, we use transsynaptic and interactional genetic tools to investigate both closed- and open-loop stratonigrostriatal circuits. We find strong evidence for closed loops, which would allow striatal subregions to regulate their own dopamine release.
We also find evidence of functional synapses in open ends. However, these synapses are unable to modulate tonic dopamine neuron firing, which calls into question the prominence of their role in mediating crosstalk between striatal subregions.
(This story has not been edited by seemayo staff and is published from a rss feed)