Summary: Although not as independently as previously believed, melatonin neurons in the brainstem interact with one another to control decision-making. Researchers discovered that serotonin neurons clusters interact and engage, which affect the release of dopamine throughout the brain.
This finding challenges conventional wisdom regarding a consistent serotonin signal, which may have significant repercussions for understanding mood issues and how the brain processes linear choices. The medial habenula, which is used to make “go” or “don’t go” choices in response to perceived threats, is a brain circuits that the group identified.
Important Information
- Serotonin Networks: Serotonin cells create connected bands that control powerful dopamine release.
- Decision Wires: A recently discovered loop directs linear decisions by linking the lateral habenula to endorphins activity.
- Behavioral Impact: This fresh knowledge might help to develop effective treatments for mood disorders like depression.
University of Ottawa Supply
Decisions between one of two options are what we make in our lives. But when we engage in this kind of decision-making, what actually happens inside our brains?
A , a faculty of medicine-led study from the University of Ottawa that is the , very beginning of our main serotonin (5-HT), a crucial component of the nervous program involved in a remarkable variety of mental and behavioral functions, sheds new light on these great questions. It illuminates a basic principle of neurological processing in this strange region of the midbrain.
The dominant theory is that each 5-HT neuron acts separately from another. Although it had recently been suggested that 5-HT cells might prefer to get connected to one another, it had not been directly demonstrated. That is what we did right below.
We also discover an interesting control part – or a processing – supported by this specific type of connectivity between 5-HT neurons, says Dr. Jean-Claude Béque, associate professor in the , Faculty’s Department of Cellular and Molecular Medicine, and co-director of the , uOttawa Brain and Mind , Research Institute’s Centre for Neural Dynamics and Artificial Intelligence.
The international research team’s work included a mix of mathematical modeling and computer simulations as well as a variety of experimental methods, including electrophysiology, cellular imaging, optogenetics, behavioral, and cellular imaging.
making advancements
What does it mean that the clustered serotonin neurons in the brainstem are actually sending axons to the rest of the brain and not just independent actors, as the term implies?
The main takeaway of the paper, in my opinion, is that the mammalian serotonin system is much more atomically and functionally complex than what we had anticipated.
Dr. Michael Lynn, the study’s first author and former member of Dr. Béque’s Faculty of Medicine lab, says that” this knowledge may help develop targeted therapeutics for mood disorders like major depressive disorder.”
In October 2023, Dr. Lynn received his PhD in neuroscience from the University of Ottawa. He is currently employed by the University of Oxford’s Department of Physiology, Anatomy, and Genetics as a postdoctoral fellow.
He claims that the team’s findings are significant because it turns out that there are various groups of serotonin neurons with distinct activity patterns, each influencing the release of serotonin in a particular area of the brain.
This has implications for the neuroscience’s “winner-takes-all” theory, which is used in computational models of neural networks where neurons essentially compete to activate each other.
The new ideas that were discovered in this paper point out that these distinct ensembles can interact in some situations:” Winning” serotonin ensembles with high activity can significantly reduce serotonin release from “losing” serotonin ensembles with lower activity levels,” he says.
In contrast to an earlier understanding of a more monolithic signal, these imply a more complicated, dynamic set of rules about how and when serotonin is released throughout the brain.
Decisions, decisions
The research team’s findings have an impact on how our brain, an organ with a ton of intricate wiring of neurons with numerous enmeshed connections, participates in daily decision-making.
They discovered how the lateral habenula, a region that is activated when we experience major depression, ultimately controls the activity of serotonin neurons.
Habenular neurons are thought to also encode the threat level perceived by a particular environment, or even by our actions.
Do we jump from the high diving board at the pool, asks Dr. Béque? Or only from the lowest one? Do we go down that ominous alley, or do we steer clear of it? When is dark too dark, you ask?  ,
You go, or you don’t, according to our brains, some way, to determine features of our world, such as how threatening a particular environment is.
We believe we have found a circuit that makes the computation that makes our daily decisions, he claims.
Next steps
What will the research team do next as they continue to improve over the years through this methodical, cutting-edge study of the serotonin system? They want to concentrate on mouse model behavioral studies.
The computation we discovered had some sort of artificial behavior at this point. According to Dr. Béque, we’re currently examining whether similar things can be observed when mice behave in more naturalistic settings.
The , uOttawa Faculty of Medicine ‘s , Dr. Richard Naud, a computational neuroscientist who served as the senior author on a recent serotonin-related study published in , Nature, and Sean Geddes, director of innovation and partnerships at Ottawa, made up the talented research team for the new , Nature Neuroscience , paper.
About this news about serotonin and decision-making research
Author: Paul Logothetis
Source: University of Ottawa
Contact: Paul Logothetis – University of Ottawa
Image: The image is credited to Neuroscience News
Original research: Free of charge.
By Jean-Claude Béque et al.,” Nonlinear recurrent inhibition by facilitating the raphe’s serotonin release“. Neuroscience of the natural world
Abstract
Nonlinear recurrent inhibition by facilitating the raphe’s serotonin release
Although the dorsal raphe nucleus ( DRN ) receives a number of long-range inputs, guiding principles of local circuit organization and computations in this nucleus are largely unknown.
We found 5-HT1A receptor-mediated recurrent connections between 5-HT neurons by using inputs from the lateral habenula to disprove traditional theories of autoinhibition.
These recurrent inhibitory connections spanned the raphe, were slow, stochastic, strongly facilitate, and gated spike output, according to cell electrophysiology and 5-HT imaging.
Excitation-driven inhibition and winner-take-all computations were produced by all of these characteristics, which collectively produced highly nonlinear dynamics for this network.
Transiently disrupted the expression of a reward-conditioned response in an auditory conditioning task by in vivo optogenetic activation of lateral habenula inputs to DRN at frequencies where these computations are predicted to ignite.
Together, these data reveal a core computation that is supported by an unsuspected slow serotonergic recurrent inhibitory network.
