Annotated Bibliography

Adapted from Desperately Seeking Sensation: Fear, Reward, and the Human Need for Novelty

Neuroscience Begins to Shine Light on the Neural Basis of Sensation-Seeking

by Brenda Patoine October 13, 2009 http://www.dana.org/News/Details.aspx?id=43484

Why are some people drawn to intense, even fear-inducing thrills while others shun the mere thought? How is it that the same horror movie can be entertainment to one person and tension-filled torture to another? Is something different going on in the brains of these people?

Sensation-seeking, the tendency to seek out novel experiences, is a general personality trait that has been extensively studied in psychological research, but neuroscience is just beginning to take aim at it.

Neuroscience is beginning to tease apart how the brain of a high-sensation seeker might be different from that of someone who generally avoids risk. Recent brain imaging studies have offered some intriguing clues, finding a direct link between the size of the hippocampus and experience-seeking behavior and shedding light on how the brain responds differently to intense or arousing stimuli in highs vs. lows.

Novelty and Intensity Key

A recent study using functional MRI, Jane Joseph, Ph.D., and colleagues at the University of Kentucky found that different brain areas are activated in high- vs. low-sensation seekers in response to strongly arousing stimuli. These findings build on a broad base of psychological science in sensation-seeking dating back to the mid-1900’s. Psychologist Marvin Zuckerman, Ph.D., now an emeritus professor at the University of Delaware, developed the original sensation-seeking scale in 1964 as part of sensory deprivation experiments. He came to define the trait and outlined four subtypes representing the various ways sensation-seeking is expressed behaviorally:

1. Thrill & Adventure Seeking: the pursuit of physical activities that are exciting, unusual and potentially dangerous (e.g., sky-diving)

2. Experience Seeking: stimulation through the mind and senses; the pursuit of unfamiliar and complex environmental stimuli, as through travel or meeting new people.

3. Disinhibition: sensation-seeking through engagement with other people; searching for opportunities to lose inhibitions by engaging in variety in sex, alcohol, drugs, etc.

4. Boredom Susceptibility: the tendency to be easily bored by familiar or repetitive situations or people, or by routine work.

Like any personality trait, there is a normal, bell-curved distribution of sensation-seeking behavior in the population, with most people falling somewhere in the middle in terms of their appetite for intense, novel stimuli, and smaller proportions at the low and high ends. This makes sense from the evolutionary perspective because “people at either extreme are at a disadvantage,” says Zuckerman. “If you’re taking too much risk you may die before you have a chance to spread your genes around, and if you’re too cautious, you may not have the advantage of obtaining resources (like food and water) that entail some risk.”

The Dopamine Connection

Some studies have found that people with higher levels of a specific type of receptor for dopamine, the primary neurotransmitter involved in reward processing, have greater sensation-seeking tendencies.

Other types of dopamine receptors that normally regulate dopamine release appear to have an opposite effect: the fewer there are, the greater the novelty-seeking behavior. These may act as brakes on dopamine release, so having fewer of them means that more dopamine is released in response to novelty. This may in turn drive reward-seeking behavior.

The involvement of dopamine in novelty-seeking behavior may also explain the well-established relationship between high sensation-seeking and drug use. High-sensation seekers are more likely to try drugs earlier, to become addicted, and to experiment with multiple drugs. Like drugs of abuse, exposure to novel stimuli releases a rush of dopamine in reward areas of the brain. And, high-sensation seekers often develop a sort of tolerance to high-risk activities—boredom sets in, and they are compelled to add new twists that recreate the initial charge.

 “They get bored,” Zuckerman says. “Even what was initially very exciting becomes blasé when you’ve done it 100 times, so you need something more exciting, something new.”

Weighing Novelty In Terms of Fear vs. Reward

Sensation-seeking also intersects with the fear system. Individual differences in how the brain responds to fear, balanced with how it is wired for reward, may help explain differences in sensation-seeking.

“There is clearly a component of excitement and novelty involved in thrill-seeking, but there is also likely to be a component of worry and fear,” says Kerry Ressler, M.D., Ph.D., a neurobiologist and psychiatrist at Emory University and a member of the Dana Alliance for Brain Initiatives. He points out that the amygdala, the brain region most associated with fear processing, is the same region involved in addictive and appetitive behaviors.

“Each of us, based on our genetic make-up and environmental influences, has different propensities for being drawn toward something that is attractive and appetitive, and on the opposite side, being averse to things that are dangerous or fearful,” Ressler says. “My guess is that the difference between a thrill-seeking person and someone who is not is probably a combination of the level of reward they get from novelty, thrill, or adventure and how much they’re afraid of it.”

“Thrill-seekers may be able to use cognitive parts of the brains to recognize that the scary movie or ride isn’t really going to hurt them,” Ressler says. “

This may be one reason frightening films are so popular, Zuckerman notes. “People who would never engage in high-risk activities themselves get vicarious excitement from movies,” he says. “They know that the [monsters] aren’t going to jump out of the screen and get them, so they get a little kick of fear in a safe environment.”