Wednesday, November 07, 2007

Violence and Neurochemicals

Really good (and long) article getting at what we talk about here regarding TECHNOCORRECTIONS and the pharmaceutical and bioengineering possibilities, this time concerning violence and neurochemicals. Read. Be enlightened. (Here are a couple of teasers.)

. . . new studies are helping scientists gain deeper insight into the neurobiology of aggression and violence. One analysis of brain imaging studies has revealed that brain structures involved in making moral judgments are often damaged in violent individuals. Another study involving teenage boys suggests that disruptions in a brain region linked to impulsive, aggressive behavior may underlie a certain type of violent, reactive behavior.

Still other research has shed new light on the role that certain brain chemicals play in aggressive behavior, including in maternal aggression. And new animal studies reveal that aggressive encounters cause changes in the brains of aggressors as well as their victims that increase vulnerability to depression and immune-related illnesses.
After analyzing data from 47 independent brain imaging studies, researchers at the University of Pennsylvania have found that the rule-breaking behavior common to people with antisocial, violent, and psychopathic tendencies may result partly from damage to the neural circuitry in the brain that underlies moral decision-making.

"This finding supports other studies that may force society to question its attitude toward the nature of crime and punishment," says Adrian Raine, PhD. "For example, should psychopaths be punished if, for reasons beyond their control, they do not have the appropriate brain circuitry to process moral dilemmas?"

Scientists have long known that damage to certain regions of the brain, most notably the prefrontal cortex, can result in violent behavior. More recently, imaging studies have identified the neural circuits that become activated in the brains of normal, healthy individuals during moral decision-making.

The analysis was undertaken to see if the brain regions compromised in antisocial populations include the newly identified brain regions involved in moral decision-making. Raine and his colleagues compared the brain images of 792 antisocial individuals with 704 control subjects. They found that antisocial individuals also tended to have overlapping damage in brain structures involved in making moral judgments, most notably the dorsal and ventral prefrontal cortex, the amygdala, and the angular gyrus.

"If offenders are not fully responsible for the source of the brain dysfunction that impairs their moral-decision making, this raises a significant neuroethical issue regarding the appropriate level of punishment for those who perpetrate morally inappropriate acts," Raine says.
New studies from the University of California, San Diego, are helping scientists better understand what goes on in the brains of some teenage boys who respond with inappropriate anger and aggression to perceived threats. Preliminary findings from these studies suggest that such behavior is associated with a hyperactive response in the amygdala, an area of the brain that processes information regarding threats and fear, and with a lessening of activity in the frontal lobe, a brain region linked to decision-making and impulse control.

"This work will provide significant neurobiologic insight into why some adolescents become aggressive and violent," says Guido Frank, MD. "Eventually, it may lead to more effective therapies for helping adolescents overcome excessively aggressive behaviors that are harmful to themselves as well as to others."
The term "reactive-affective-defensive-impulsive" (RADI) has recently been created to describe such behavior. Research suggests that adolescents with RADI behavior are at an increased risk for a lifetime of problems associated with impulsive aggression. "A major problem in researching this topic is stigma and a notion that children will grow out of aggressive behaviors," Frank says. "It's often difficult to recruit such youngsters and their families to participate in research."

Little is known about how the brain works in reactive aggression. In their most recent studies, Frank and his colleagues recruited two groups of male adolescents: one group diagnosed with RADI behavior and the other group without any history of mental illness or aggression problems. While being scanned by a brain imaging machine, both sets of teenagers were asked to perform tasks that involved reacting to age-appropriate, fear-inducing images. The tasks also tested the teenagers' impulsivity.

Preliminary data reveal that the brains of RADI teenagers exhibited greater activity in the amygdala and lesser activity in the frontal lobe in response to the images than the brains of the teenagers in the control group. In a related study, Frank and his colleagues are investigating whether these changes in brain activity are associated with an abnormal increase in cortisol levels, a marker of the stress response.
More recently, de Boer and his colleagues have found that the transition from normal, adaptive aggressive behavior into abnormal forms that inflict harm and injury is due to functional, but not structural, changes in certain serotonin receptors in the brain. In animal studies, treatment with selective serotonin receptor agonist compounds has been found to restore the normal function of these receptors-and suppress aggressive behavior, including its escalated forms. These findings may one day lead to more effective treatments for violent behavior in humans.

[If this article interests you, there’s a related one here on the impact of neurochemicals on “rational” decision-making that’s come out of the new neuroeconomics field. Chemicals and the ability to think clearly on costs and benefits of actions . . . maybe that does have something to do with corrections sentencing.]

No comments: