Developing a response to fear is part of the natural response from animals. It’s a survival strategy from being in the environment. The fear response requires coordinated neural activity in specific regions of the brain: the hippocampus, medial prefrontal cortex, and amygdal. These three brain regions areas connected to one another.
The hippocampus belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. With the prefrontal cortex, this brain region has been implicated in planning complex cognitive behavior, personality expression, decision making, and moderating social behavior. The amygdala performs a primary role in the processing of memory, decision-making, and emotional reaction.
However, sometimes things go wrong and the fear response becomes all-encompassing. For instance, a disruption of the fear formation process can generate a maladaptive generalized fear as with post-traumatic stress disorder. The condition is arguably more noticeable in society (whether this is due to improved detection rates or social effects is uncertain). In the U.S., for example, the rate is around 7 percent of the population.
Researching memory formation and the association with post-traumatic stress disorder, researchers Jun-Hyeong Cho and Woong Bin Kim have discovered that a population of hippocampal neurons project to both the amygdala and the medial prefrontal cortex. These neurons appear to effectively transfer information to these two brain areas to encode and retrieve fear memory.
To show this connection the researchers used an imaging technique that involved the use of labeled fluorescence proteins with different colors. The use of color was key to tracing the interconnections. The science behind this is called electrophysiological recordings (which relates to the study of the electrical properties of biological cells and tissues) and optogenetics (a biological technique which involves the use of light to control cells in living tissue, typically neurons).
In a research briefing, Dr. Cho explains: “This study, done using a mouse model, expands our understanding of how associative fear memory for a relevant context is encoded in the brain.”
In terms of the significance, the researcher adds that the findings “could inform the development of novel therapeutics to reduce pathological fear in post-traumatic stress disorder.”
The new research has been published in the Journal of Neuroscience. The research paper is titled “Synaptic Targeting of Double-Projecting Ventral CA1 Hippocampal Neurons to the Medial Prefrontal Cortex and Basal Amygdala.”
