Transforming Encounters into Emotions: The Neural Process
Anger escaping traffic can leave you fuming throughout your journey, and a new research study suggests that this emotional response could be a result of specific brain activity. NPR's Jon Hamilton investigated this process in the brain.
As a psychiatrist at Stanford University, Dr. Karl Deisseroth specializes in understanding how people manage their emotions. He contends that emotion is a broad state that affects the brain. To explore this idea, Deisseroth and his team of scientists created an experiment to replicate the anger-inducing feelings often encountered in daily life.
They opted for a mild, yet bothersome stimulus - a puff of air to the cornea, similar to a glaucoma test at the eye doctor. Deisseroth found that this tactile irritation caused an involuntary blink reflex in both mice and humans. Prolonged exposure to the puffs resulted in both species maintaining a squint in self-defense.
The researchers then studied the brain activity associated with these experiences, discovering two distinct phases of brain activation. The first phase is rapid, spanning mere fractions of a second, and involves a surge of activity in brain circuits responsible for processing sensory input. After this brief initial phase, activity moved to other circuits, including those involved in emotion. This second phase is more prolonged, and with each successive puff of air, the response strengthened, lingering like a sustained piano note.
In humans, the stronger the brain response, the more they squinted, and the more annoyed they felt about the experience. Meanwhile, the mice's protective blinking and decreased willingness to seek rewards suggested the same emotional response was at play.
To confirm their findings, the researchers repeated their experiment while both mice and humans were under the influence of ketamine, an anesthetic that disrupts the brain's processing of sensory information. While both species still blinked reflexively to the air puffs, they didn't persistently squint, and the second phase of brain activity was absent. Deisseroth concluded that removing this sustained phase eliminated emotion and the emotional response.
The study is published in the journal Science. While the research clearly demonstrates how an experience can affect a creature's underlying mental state, Professor Lisa Feldman Barrett of Northeastern University cautions that sustained activity in certain brain circuits does not necessarily indicate an emotion. Instead, she suggests that emotional responses may entail much more nuanced brain processes, including remembering and paying attention.
Barrett also notes that the air puffs may have a different meaning to a mouse compared to a human, adding to the common concern among neuroscientists about interpreting emotional responses in animals. Nevertheless, the study adds valuable insights into the complex process of anger in both humans and animals, highlighting the brain's ability to transform brief stimuli into a sustained emotional state.
This study suggests that the brain's activity during anger-inducing experiences, like traffic, could be related to mental health. Dr. Karl Deisseroth, a psychiatrist at Stanford University, found that a prolonged response to a mild, irritating stimulus, such as a puff of air, can lead to increased brain activity in emotion-related circuits, causing emotions like anger in both humans and mice. The findings were published in the journal Science, but Professor Lisa Feldman Barrett of Northeastern University emphasizes that the study doesn't fully explain emotional responses, as they may involve more nuanced brain processes, including attention and memory.
