Researchers have discovered that rats develop mental maps of areas to steer clear of after encountering a threat and reflect on these spaces when showing signs of anxiety. This research may enhance our understanding of the brain functions related to common mental health issues, such as anxiety.
Researchers have discovered that rats develop mental maps of areas to steer clear of after encountering a threat and reflect on these spaces when showing signs of anxiety. This research, presented by A. David Redish and colleagues from the University of Minnesota in the open-access journal PLOS Biology on January 14, may enhance our understanding of the brain functions related to common mental health issues, such as anxiety.
There are various theories about the reasons behind anxiety in individuals. One explanation points to a psychological concept known as “approach-avoidance conflict,” where a person desires something but contemplates the possible negative consequences.
To investigate the brain mechanisms behind this concept, researchers observed rats as they navigated an L-shaped track. The rats began at one end of the track, where food was located at the opposite end, while a robotic creature resembling a mix between a pincer beetle and a scorpion, with claws and a stinger-like tail, lurked partially hidden around the corner.
As the rats moved closer to the food, the robotic threat would sometimes charge at them, snapping its claws and waving its tail to imitate an attack. Following these encounters, the rats began to display avoidance behaviors, such as pausing or retreating to safety, which the researchers linked to their anxiety about the robot.
Some rats used in the study had probes implanted to monitor activity in the hippocampus, a brain region thought to play a role in learning and memory. The researchers zeroed in on the activity of specific neurons called “place cells,” which become active when an animal visits particular locations. By analyzing this neuronal activity, they could identify which place cells were linked to the food’s location or the robot’s position.
When the rats paused while approaching the food, the researchers noticed heightened activity in place cells relating to both the food and the robot’s locations. This response may reflect the approach-avoidance conflict between the desire for food and anxiety concerning the robot. However, when the rats turned back partway through the track, the place cells primarily associated with the robot became active.
Typically, place cells activate only when an animal is at or near the location linked to those cells. However, when the rats turned around and fled to the safer end of the track, their place cells connected to the robot remained active even at a distance.
Anxiety is linked to the capacity to envision various situations, a function associated with the hippocampus and place cells. The sustained activity of place cells related to negative events — particularly when the events are perceived as remote — may facilitate a better understanding of the neuroscience behind anxiety.
Supporting this connection, the researchers noted a significant decrease in anxiety-related behaviors among the rats treated with diazepam, commonly referred to as Valium. This medication also modified the hippocampus’s activity, diminishing the neural patterns connected to anxiety-like behaviors.
The authors further explain, “Worrying about what might happen requires mental imagery of anticipated negative outcomes. Rats confronted by a predator-like robot guarding a food supply generated new mental images of the robot’s position, causing them to briefly consider the robot’s whereabouts before going for the food.”
