We are all afraid of some or many things. Fear is a very common response, especially darkness. This fear of the dark is usually seen in children. But now scientists believe they may have discovered the brain mechanisms behind this fear. These mechanisms work in certain areas of the brain.
The section of the brain that is responsible for processing emotion and regulating a person’s fear response is the amygdala section. In the new study, scientists highlighted how brain activity in this part of the brain changes when people are exposed to light or dark.
“Light, compared to darkness, suppresses activity in the amygdala. Moderate light exposure resulted in greater suppression of amygdala activity than dim light,” the researchers wrote.
Furthermore, the presence of light seems to strengthen the connection between the amygdala and the ventromedial prefrontal cortex, which is another part of the brain that is involved in controlling the feeling of fear .
In the new study, fMRI brain scans were performed on 23 people. And they were analyzed as they were exposed to 30-second periods of low and moderate lighting, as well as darkness. Altogether the exams lasted 30 minutes.
Moderate lighting made a significant reduction in amygdala activity. The dim lighting ended up making a smaller reduction. In addition, greater functional connectivity between the amygdala and the ventromedial prefrontal cortex was also seen at times when the lights were on.
Light and dark
That is to say, light can keep the brain’s fear management centers in operation. This conclusion was based on this small group of volunteers, so researchers will need more data to figure out what exactly is going on.
“These effects may contribute to the mood-elevating effects of light through a reduction in fear- related negative affect and improved processing of negative emotion,” the researchers wrote.
This relationship between light, dark and activity in the brain is well established. Changes in light help people know when to sleep and also have an impact on alertness and mood.
It is possible that being able to control the light is a way of dealing with the fear of the dark. And we see that phototherapy treatments are used widely for illnesses like depression, even if scientists don’t fully understand how or why they work.
The answer may lie in so-called intrinsically photosensitive retinal ganglion cells (ipRGCs), which are cells that capture light from the eyes and transmit it to different areas of the brain. After that, the next step is to understand more about how they interact with the amygdala.
“Further work will be needed to begin to understand the unique contribution of different subsets of ipRGCs and other photoreceptors to both the visual and non-visual aspects of responses to light,” concluded the researchers.