Summry: New study reveals that serotonin plays a vital part in teaching younger men mice to struggle, with the chemical’s impact diminishing as they gain experience. In amateur soldiers, boosting serotonin increased anger, while blocking it stopped them from fighting.
However, expert fighters showed no changes in behavior regardless of serotonin deception, highlighting the role of knowledge in shaping anger. The research identifies the lateral membrane as a key mental area for “aggression learning ” in men, but no related effect was observed in women.
Important Facts:
- Dopamine’s Role: Dopamine promotes anger in amateur male mice but becomes less prominent with experience.
- Mental Region Identified: The longitudinal septum facilitates dopamine’s effects on hostility learning in males.
- Gender Variations: Dopamine deception did not impact aggressive behaviors in adult mice.
Origin: NYU Langone
Like humans, animals will engage over territory and colleagues, and show increased trust in their fighting abilities the more they win. At initial, a brain chemical called serotonin is important for young men to grasp this conduct. But as they gain experience, the substance grows less essential in promoting anger, a new study indicates.
Dopamine has been linked to female anger for centuries. How prior experiences may influence this partnership, however, had until then been unclear.
In research in rabbits, a team led by researchers at NYU Langone Health boosted action in dopamine-releasing tissue in a part of the brain called the lateral tegmental area.
The results revealed that in inexperienced adult fighters, this led the creatures to strike for twice as long as they would possess fought normally. When the tissues were blocked, the novice animals do not struggle at all.
By comparison, this routine did not hold true in men that had considerable fighting experience. Whether or not dopamine-releasing tissues were boosted or blocked, the length of assault did not change. Importantly, though, the more conflicts a rat fought, the more fights it may start in the future.
“Our findings offer new insight into how both ‘nature ’ and ‘nurture ’ shape aggression in males, ” said study senior author Dayu Lin, PhD.
“ While anger is an innate habits, serotonin — and fighting experience— is necessary for its development during adulthood, ” added Lin, a teacher in the Ministries of Psychiatry and of Neuroscience at NYU Grossman School of Medicine.
A review on the results is publishing virtual Jan. 22 in the journal Character.
Building on their information for the role of serotonin in learning anger, artists set out to better understand the mind systems that might explain it. To do this, the team prevented cells in the ventral tegmental area of the brain from releasing dopamine into another region called the lateral septum, a site known to regulate aggression.
They found that novice males would never learn to fight, but those with previous fighting experience would continue to engage in aggressive behavior. Similarly, promoting dopamine release in this area of the brain boosted hostility in rookies but had no effect on veterans.
This suggests that the lateral septum is a key brain site for dopamine to promote “aggression learning ” in rodents and likely in other mammals, including people, says Lin, who is also a member of NYU Grossman School of Medicine’s Institute for Translational Neuroscience.
The team also measured dopamine release in the lateral septum as the animals gained fighting experience. They found that the chemical surges the most on the day they first decide to attack.
As the mouse becomes more experienced with fighting, this dopamine spike becomes less dramatic, supporting a central role of the chemical in initial aggression learning.
Importantly, the researchers also found that dopamine did not appear to play a similar role in female aggression. In fact, manipulating dopamine levels did not affect aggressive behaviors in female mice in any way.
According to Lin, the results may offer new insight into addressing mental health conditions marked by intense shifts in mood and behavior, such as schizophrenia, bipolar disorder, and borderline personality disorder.
Antipsychotic drugs that interfere with dopamine release are commonly used to treat such diseases, as well as to suppress violent behavior in psychiatric patients.
“Our results suggest that targeting dopamine may not be an effective tool when treating those with a long history of aggression, ” said Lin.
“As a result, healthcare providers may need to consider a patient’s history, as well as their age and sex, when considering which therapy to use. ”
Lin adds that the results may also explain why antipsychotic drugs are known to have a stronger and longer-lasting effect in children than in adults, for whom aggression often returns once they stop receiving medication.
That said, Lin cautions that while mice share similar brain chemistry with people and that the current findings echo human clinical results, more research will be needed to demonstrate the impact of past behavior on the effectiveness of antipsychotic medications in humans.
Funding: Funding for the study was provided by National Institutes of Health grants R01MH101377, R01MH124927, U19NS107616, U01NS11335, U01NS12082, P30DA048736, and R01MH133669. Further study funding was provided by the Vulnerable Brain Project.
In addition to Lin, other NYU Langone researchers involved in the study are Bingqin Zheng, MS; Xiuzhi Dai; Xiaoyang Cui, BS; Luping Yin, PhD; Jing Cai, PhD; and Nicolas Tritsch, PhD.
Other study investigators include Yizhou Zhuo, PhD, and Yulong Li, PhD, at the Peking University School of Life Sciences in Beijing; and Larry Zweifel, PhD, at the University of Washington in Seattle. Bing Dai, PhD, a former graduate student at NYU Langone and a current postdoctoral associate at the Massachusetts Institute of Technology in Cambridge, served as the study lead author.
About this aggression and neuroscience research news
Author: Shira Polan
Source: NYU Langone
Contact: Shira Polan – NYU Langone
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Experience-dependent dopamine modulation of male aggression ” by Dayu Lin et al. Nature
Abstract
Experience-dependent dopamine modulation of male aggression
Numerous studies support the role of dopamine in modulating aggression, but the exact neural mechanisms remain elusive. Here we show that dopaminergic cells in the ventral tegmental area (VTA ) can bidirectionally modulate aggression in male mice in an experience-dependent manner.
Although VTA dopaminergic cells strongly influence aggression in novice aggressors, they become ineffective in expert aggressors. Furthermore, eliminating dopamine synthesis in the VTA prevents the emergence of aggression in naive mice but leaves aggression intact in expert aggressors. VTA dopamine modulates aggression through the dorsal lateral septum (dLS), a region known for aggression control.
Dopamine enables the flow of information from the hippocampus to the dLS by weakening local inhibition in novice aggressors. In expert aggressors, dLS local inhibition naturally weakens, and the ability of dopamine to modulate dLS cells diminishes.
Overall, these results reveal a sophisticated role of dopamine in the rise of aggression in adult male mice.
