Summary: A recent study demonstrates how a crucial neurological transfer in the brain is altered to fine-tune instinctual fear responses. Researchers compared two deer-mouse species to discover that forest-dwelling animals have sensitive avoid circuits, while open-field mice are more likely to thaw.
This is due to the dorsal periaqueductal gray (dPAG ), a brain center for defensive actions, which is more readily triggered in forest mice. The findings demonstrate how natural selection changes existing head channels rather than creating new ones, allowing for adaptation to preservation actions.
Important Information
- Neurological Switch identified: dPAG awareness regulates the flee-or-freeze impulse.
- Differences between species: open-field mice ice more frequently and forest mice evade more quickly.
- Biological Insight: Behaviors are altered by main circuits, not by sensory input.
Origin: VIB
A crucial neurological change, according to researchers, determines whether animals will automatically retreat or remain frozen. They discovered that this change is influenced by creation by the habitat of the animal by comparing two carefully related deer-mouse species.
This neural circuits is more sensitive in thickly vegetated mice, causing them to flee quickly, but less flexible in their open-field relatives, who are more likely to freeze. The research team did so by revealing an important way in which development fine-tunes the mind for life.
Flee or thaw
The body’s protective circuits are designed specifically for this purpose, and survival depends in nature on making the right choice in the right split-second option when danger strikes. However, the “right” response is dependent on the landscape: moving quickly into the underbrush may keep your life in crowded woods, while moving slowly into grassland can save you time. How does creation approach this conundrum?  ,
An international team of researchers from Belgium and the USA has discovered an elegant system that, by altering the responsiveness of a danger-response gateway in the mind, tailors conduct to each atmosphere without redesigning the entire system in a new study published in , Nature.
open-field mice vs. jungle animals
Forest mice ( Peromyscus maniculatus ) flee for safety when a shadow of a potential predator appears overhead, while their open-field cousins ( Peromyscus polionotus ) freeze in place. The researchers attempted to identify the head switch that triggers those same instincts.
Felix Baier, co-first author and member of the research group at Harvard, explains that” to accurately assess avoid habits, we presented both types of mice with stimuli that resembled an underwater predator in a controlled environment.”
We discovered that open-field mice required almost twice the signal power to avoid when compared to their forest relatives, which suggests that there is a significant difference in how they respond to the threat stimulus.
A mental change
The researchers used cutting-edge neural recordings made with Neuropixels probes and manipulation techniques to identify these behavioral differences by tracing these behavioral differences to a central command center for escape actions: the dorsal periaqueductal gray (dPAG ), a group of neurons deep in the brain, using cutting-edge neural recordings with Neuropixels probes and manipulation techniques.
We were surprised to discover that evolution moved in a northern brain region, downstream of external sensory perception, because it is frequently believed that changing behavior would require the simplest and most effective method, based on the fact that it was done downstream of peripheral sensory perception.
Both species perceive the looming danger similarly when the animals see the stimulus without acting on it as evidenced by superior responses along the loop from the vision to the dPAG. However, the dPAG’s detection was drastically different in the situation where the animals escaped the threat.
The dPAG’s” smart contrast” between the two’s neuronal activity monitoring revealed, “in contrast, the dPAG’s “run” command in the dPAG’s open field cousin sends no such commands….
Katja Reinhard, the other co-first author and former postdoc at NERF ( part of imec, KU Leuven, and VIB ), says that” this divergence can be understood as an evolutionary repurposing of neural circuits to fine tune survival response.” She is now the head of her own group at SISSA, Italy.
Additionally, the team established a direct relationship by employing cutting-edge techniques to silence or activate certain brain regions. Even in the presence of a risk, deliberately stimulating dPAG cells enabled forest mice to flee. In contrast, lowering their exit threshold by using chemical techniques to lessen dPAG activity increased their behavior, resulting in a more similar behavior to that of their cousins.  ,
Freedom is included
According to lead authors Prof. Karl Farrow ( imec, KU Leuven, VIB ) and Prof. Hopi Hoekstra ( Harvard ), the study not only clarifies how instinctive behaviors like freezing or fleeing are controlled but also highlights how flexible the brain’s internal architecture is.
Farrow:” By comparing these two connected species, we found a change that balances ice over flight, showing how healthy selection fine-tunes behavior without rewiring the senses.”
Hoekstra:” Our new revelation illustrates a fundamental biological process: natural selection frequently modifies existing neural circuits rather than creating entirely new channels.”
Funding
The Marie Skodowska-Curie fund, FWO, ERC, Harvard PRISE fellowship, Harvard Museum of Comparative Zoology grant for undergraduate research, the NIH, and the Howard Hughes Medical Institute provided financial support to the research team at the VIB-KU Leuven Center for Brain and Disease Research.
About this news from research in evolutionary neuroscience
Author: Joran Lauwers
Source: VIB
Contact: Joran Lauwers – VIB
Image: The image is credited to Neuroscience News
Open access to original research
By Katja Reinhard and colleagues,” The neural basis of species-specific defensive behavior in Peromyscus mice.” Nature
Abstract
The neural basis of Peromyscus mouse species-specific defensive behavior
Animal survival requires avoiding imminent threats from predators. Even between closely related species, effective defensive strategies can vary. The neural basis of these species-specific behaviors, however, is still poorly understood.
Here, we discover that the two sister deer species ( genus Peromyscus )   ) exhibit different responses to the same looming stimulus: Peromyscus maniculatus, which primarily evades densely vegetated habitats, while Peromyscus polionotus, which occupys densely vegetated habitats, surprisingly briefly freezes.
This distinction is largely context-dependent, has species-specific escape thresholds, and can be triggered by both visual and auditory threat stimuli.
We discover that despite visual threat activating the superior colliculus in both species, the dorsal periaqueductal grey (dPAG ) has a different role in driving behavior based on immunohistochemistry and electrophysiological recordings.
While P. maniculatus, P. polionotus, and P. polionotus ‘ dPAG activity correlates poorly with movement and is affected by visual-triggered escape, P. maniculatus ‘ dPAG activity does not correlate with movement.
In addition, dPAG neurons ‘ optogenetic activation causes acceleration in P. maniculatus and P. polionotus, but not P. polionotus, and their chemogenetic inhibition during a looming stimulus causes escape onset in P. maniculatus and P. polionotus to be comparable to that of P. polionotus and P. maniculatus.
Together, we identify species-specific escape thresholds at a central circuit node downstream of peripheral sensory neurons, thereby localizing an ecologically relevant behavioral difference to a particular region of the mammalian brain.
