The fight or flight response is now called the fight, flight or freeze response. Stress specialists around the world are adding the word freeze to the name regarding the fact that instead of fighting or fleeing, occasionally we tend to freeze during traumatic situations.
The fight or flight response is about survival. It gives us an extra boost of energy or adrenaline when we need it. We activate it when we believe there’s a chance we can outrun or outfight our attackers. The freeze response, however, gets activated when we think that there is no hope for us to either escape or go into battle during emergency situations.
The fight or flight response has been around since the prehistoric times, where our ancestors had to use conserved energy in their bodies to gear up and run or defend themselves against enemies. The response is very adaptive because it allowed our ancestors to survive through centuries.
However, the freeze response works differently. When we’re overwhelmed by an enemy, and we decide that there is no hope for us to escape and there is no chance for us to win if we battle the enemy, the survival mechanism that our body does is to freeze.
To understand about the freeze response, researchers funded by the National Institutes of Health were tasked to study the freeze response in mice. The researchers described a new circuit involved in fine-tuning the brain’s decision either to hide or confront threats.
Jim Gnadt, Ph.D., Program Director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) said that being able to manipulate specific circuits can uncover surprising relationships between brain areas and provide great insight into how the sensory, emotional, and behavioral centers work together to drive reactions. The tools and technologies developed through the BRAIN Initiative have made studies such as this one possible.
Dr. Andrew Huberman, Ph.D., Professor of Neurobiology and Ophthalmology at Stanford University in California and his team of researchers investigated the role of the Ventral Midline Thalamus (vMT) in determining how animals respond to visual threats. The thalamus is a brain region that acts as a relay station, taking in sensory information, such as what is seen and heard, and sorting out where in the brain to send that information.
Dr. Huberman and his team showed that the vMT was activated when mice were confronted with a threat, precisely a black circle that grew larger on top of their cage, mimicking the experience of something looming over them. When faced with the looming threat, the mice spent most of the time freezing or hiding and very little time rattling their tails, which is typically an aggressive response.
Dr. Huberman said that the study might help explain why acts of courage, such as standing up for yourself or a cause, or a physical challenge can feel empowering. Experiencing that satisfying feeling can also make it more likely to respond to future threats similarly. He added that although their study was done in mice, learning more about the vMT may provide some insight into conditions such as generalized anxiety disorder and post-traumatic stress disorder and we are now pursuing the study of the human vMT for that reason.