Acrophobia, the fear of heights, is a common emotional response in daily life. When people are at a high place, they involuntarily experience weakness in the limbs, rapid heartbeat, and cold sweats. But what causes this reaction?
Chinese scholars have conducted research on innate acrophobia reactions and unexpectedly discovered that the non-imaging visual system in the mouse brain triggers the fear of heights. The research findings by the team of Yuan Xiaobing and Pan Yixuan from the School of Life Sciences at East China Normal University were published in the prestigious international academic journal Nature Communications.
It is known that thousands of years ago, both the Eastern "Huangdi Neijing" and the Western "Hippocratic Corpus" described the fear of heights experienced by people. How does acrophobia occur? What is the scientific mechanism behind it? Why are some species not bothered by the fear of heights? To these intriguing "neuroscience" questions, the scientific community still lacks definitive answers. Identifying the "workstation" in the brain that specifically processes the threat of heights, finding the neural circuits and regulatory mechanisms to overcome the fear of heights, will help improve the daily lives and work of many acrophobic individuals.
Based on human acrophobia reactions and behavioral characteristics, researchers have developed a set of quantitative analyses of acrophobia reactions in mice. They found that mice can perceive the stimulus of "heights" and exhibit behaviors such as restricted movement, lowered center of gravity, anxiety, and trembling similar to humans when on an open high platform.
After inhibiting the function of the mice's peripheral vestibular organs, researchers found that their fear of heights did not decrease but instead increased. Deprivation of whisker-mediated touch also did not affect acrophobic behavior. Interestingly, mice only exhibited fearful reactions in bright areas, not showing typical acrophobic responses in dark areas, indicating that acrophobia is mainly caused by visual shock from heights.
Researchers found that blocking the primary visual cortex (V1) closely related to imaging vision did not significantly change the level of acrophobia in mice; however, inhibiting neural circuits directly related to visual signals significantly reduced the level of acrophobia in mice. This suggests that the circuit related to non-imaging vision is an important "workstation" in the brain that mediates the generation of acrophobic emotions.
The research team noted that this indicates that the stimulus of "heights" can trigger fear without the need for higher cognitive centers for analysis and judgment. Therefore, the fear that arises when one is at a high place is not just timidity but a genuine lack of control.
The team also discovered that inhibiting the activity of relevant brain areas produces a strong acrophobia-blocking effect. In such cases, many mice can completely ignore the danger on the high platform and bravely climb down or jump off. This phenomenon suggests that the "workstation" transmitting signals of height danger is not unique and may involve other unknown brain areas that collectively trigger rapid avoidance fear responses.
