Innate defensive behaviors such as flight, freeze, and fight are critical for animals to survive in a dangerous environment. Neuroscientists at the City University of Hong Kong (CityU) have recently unveiled the essential neurocircuitry essential for animals to perceive and integrate environmental cues to initiate defensive behavior. The results suggest a new direction for further investigation in developing a treatment for schizophrenic patients suffering from auditory hallucinations.
The research, led by Professor He Jufang, Wong Chun Hong Chair Professor of Translational Neuroscience, and Dr. Chen Xi, a research assistant professor in the Department of Neuroscience at CityU, showed how the anterior cingulate cortex (ACC) and auditory cortex (ACx) in the brain work together to help mice increase their survival rate when threatened threatens. The study was recently published in the journal cell reportsentitled “The anterior cingulate cortex directly amplifies auditory cortical responses in airburst-facilitated flight behavior.”
In wildlife, noticeable environmental cues, such as air currents or puffs of air, followed by unusual noises can signal an approaching danger, such as: B. an attack of a predator. In order to improve the reaction time of their defensive response, animals must perceive and integrate these dangerous cues as quickly as possible in order to increase their chances of survival by escaping more quickly. But how do animals do it?
Neural mechanism behind flight behavior
“Over the past decade, scientists have studied defensive behavior and the underlying neurocircuitry in individual sensory modalities. However, little was known about how a salient cue affects innate defensive behavior, which is important for improving survival when an animal faces imminent danger,” said Dr. Chen.
Previous studies have shown that a high-intensity sound can induce innate flight behavior. In this study, the team introduced the animal’s air puff to mimic a distinctive environmental cue before a high-intensity sound. Using anatomical, physiological, optogenetic and chemogenetic methods, the research team investigated how the anterior cingulate cortex, which is responsible for cognitive functions, and the auditory cortex circuitry control flight behavior in mice.
In their experiments, CityU researchers measured the running speed of mice in response to puffs of air and noise at different air pressures and sound intensities. The change in pupil size and brain activity in the mice was recorded in detail using techniques such as fiber photometry and extracellular recording.
Experiments on the effect of air blasts and noise
First, the research team showed that blowing air enhanced sound-induced flight behavior in mice. In the experiment, they found out that noise causes flight behavior, especially at high intensity. Then they investigated how a puff of air presented before the sound affects flight behavior. They found that even a slight puff of air can elicit increased flight behavior (the mice ran faster) if the puff of air is followed by a sound. This model offers a new way to understand innate defensive behavior in the future.
Second, the team demonstrated that the anterior cingulate cortex encodes the air burst information and amplifies the auditory response through its projection onto the auditory cortex, thereby facilitating flight behavior. They also proved that this neural circuitry is essential for animals to integrate blowing and sound. Inhibiting the anterior cingulate cortex or its projections to the auditory cortex neutralizes this assistive effect.
Previous studies on the top-down modulation of the auditory cortex have primarily focused on how motor areas transmit movement-related information to it. But in this study, the research team showed that the prefrontal area of the brain, which plays a central role in cognitive control functions such as influencing attention, predicting the consequences of the subject’s actions, and anticipating events in the environment, also improves can auditory cortical activity in mice.
The research team believes that the neurocircuitry of the anterior cingulate cortex-auditory cortex (ACC-ACx) is essential for animals to integrate air bubbles and sounds. Activation of this circuit can be critical to animal survival in the natural environment. For example, air currents and unusual sounds together are more likely to help animals predict the appearance of predators than sounds alone, allowing animals to escape more quickly.
Possible solution for auditory hallucinations
“However, every coin has two sides,” said Professor He. He pointed out that pathological overexcitation of the anterior cingulate cortex can produce an overactive state in the auditory system, which can cause auditory hallucinations. “This study suggests that inhibiting anterior cingulate cortex hyperarousal may help minimize auditory hallucinations and provides new direction for developing a treatment for schizophrenic patients suffering from this symptom,” said Professor He . “Further research is needed to understand the mechanisms of projection of the anterior cingulate cortex onto sensory cortices and possible correlations with such pathological conditions.”
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Wenjian Sun et al., The anterior cingulate cortex directly amplifies auditory cortical responses in airburst-facilitated flight behavior, cell reports (2022). DOI: 10.1016/j.celrep.2022.110506
Provided by City University of Hong Kong
Citation: Scientists unveil the neurocircuitry vital for animals to recognize environmental cues of imminent danger (2022 May 5), retrieved May 5, 2022 from https://phys.org/news/2022-05-scientists -reveal-neurocircuitry-essential-animals. html
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