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Investigating the Underpinnings of Fear, Trauma, and Depression

Posted Feb. 4, 2013

Beneath the surface, at the cellular and molecular levels of our brains, neurobiological mechanisms control our emotions. 

To better understand those neurobiological mechanisms, Kent State Assistant Professor of Psychology Aaron Jasnow studies mice to examine the role of particular genes, the interaction of those genes with the environment, and how that affects their emotions.

His colleagues in the Department of Psychology, Assistant Professor Karin Coifman and Professor Douglas Delahanty, are collaborating with Jasnow to investigate particular human genetic polymorphisms that are associated with emotion regulation, cognitive flexibility and the ability to recover from a traumatic event.  

They want to know whether they can predict, by using cognitive tests, emotional tests, and gene analysis, who will recover and who will not. The researchers also want to determine whether more intensive therapy can aid those who appear less likely to recover.  

Since joining Kent State in summer 2011, Jasnow and his colleagues have been addressing two key questions in this area of neuroscience, namely: (1) What are the basic mechanisms of fear? and (2) How does social stress in animals affect future learning, fear and emotion? The animal research might provide a better understanding of these same issues in humans. 

In looking at the basic mechanisms underlying fear learning, Jasnow also focuses on fear extinction and the generalization of fear. One of the issues with phobias and other neuropsychiatric diseases is that they tend to generalize over time or generalize to a nonspecific cue. For example, a man develops a phobia because he was bitten by a dog, so initially he is afraid of that particular dog, but then his fears may generalize to other dogs.

There is a tendency toward stimulus generalization, in which responses become conditioned, and similar stimuli evoke comparable responses. For example, if a child has been conditioned to fear a stuffed white rabbit, he or she will exhibit fear of objects similar to the conditioned stimulus, such as a white toy cat. 

This type of generalization can also occur for someone who develops post-traumatic stress disorder (PTSD) after experiencing disturbing events such as war. "A trauma happens at a specific time and place, with a specific occurrence and specific cue, and that can tend to generalize across different contexts and different cues," Jasnow explains. "For example, a war veteran may hear a car backfire, which generates an emotional response of fear, even though the individual is no longer in the war environment. We seek to understand the basic mechanisms of fear learning and extinction and how that can generalize across contexts," he says.

Jasnow's other research involves social interaction, using a model of social degeat or depression. Studying animals, he hopes to better understand how social subjugation or social stress affects future learning, fear and/or emotion.

"We generally find that animals that have been defeated tend to spend less time interacting, and they try to get away from other animals," Jasnow says. "We're striving to see how that generalizes to other fear stimuli.  Will that generalize, and will that change future emotional responses?"

Jasnow says he also wants to investigate: What is the gene by environment interaction that causes that change?  What genes are involved?  And, how does the environment play a role in interacting with those genes to alter emotion, fear, and responses to stress? 

Discussing how brain research in laboratory mice correlates to brain research in humans, Jasnow says, "A neuron is a neuron is a neuron, and it doesn't matter where that neuron is. Obviously a human brain is more complex than a mouse brain. But if we can understand in mice some of the basic mechanisms underlying fear learning or responses to traumatic events such as social defeat, we can try to nail down those biological and molecular underpinnings occurring in the brain. We can then try to translate these findings into human research."

Jasnow goes on to further explain, "By understanding  basic biological functions using animal models, we can apply our insights to what's going on biologically in humans. That's the goal for most of our research."