Blaming the teen brain

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A growing field of neuroscience research suggests teenagers take more risks, don't focus on consequences and tend not to reason things out because there's too much going on in their heads.The studies show brain maturation continues many years longer than scientists once thought. Researchers think an overabundance of gray matter and still-strengthening connections between different parts of the brain may influence how teens behave, though the exact link isn't understood.A tug-of-war over whether the science belongs in the courtroom seems likely to emerge in the nationally publicized case of Brandon McInerney. The 14-year-old from Oxnard, Calif., is set to be tried as an adult in the Feb. 12 classroom killing of Larry King, a 15-year-old who sometimes wore lipstick and told friends he was gay."We're going to do everything we can to make it a part of the defense because we think it's extremely relevant," said William Quest, Ventura County senior deputy public defender. "The crux of homicide is you have this intent to kill. It's thought out and coherent. If there is something that, given your brain development, puts you in a state that is not coherent, it mitigates that intent."But as lawyers and juvenile justice advocates try to push the research into the debate on whether any minors should be tried as adults, others, including scientists involved with the research, push back. They say brain science is still marked by too many unanswered questions to be used as a defense for a murder or assault."You'd be hard pressed to draw that connection," said Dr. Arthur Toga, director of the neuro-imaging laboratory at UCLA. He worries science is being twisted into an excuse for violence."I personally believe in individual responsibility," he said.McInerney is accused of shooting King in the head about 8:30 a.m. Feb. 12 in Room 42 of E.O. Green School in Oxnard, where students were working on English assignments. Charged with first-degree murder and a hate crime, he has not entered a plea and is scheduled for arraignment on Thursday.Senior Deputy District Attorney Maeve Fox said the decision to try McInerney as an adult could be reviewed if compelling evidence is presented. She said she doesn't know much about brain maturation research, comparing it to the lawyers who years ago brought brain images from scans known as positron emission tomography or PET. All she saw were charts with pretty colors."A lot of trendy medical procedures have come and gone as far as potential defenses to crime without ever having validated themselves," she said.If the brain is a symphony of thoughts, feelings and actions, the prefrontal cortex is its conductor, waving a baton from the frontal lobe. It influences how people process information, decide how to deal with anger, and choose whether racing across an intersection to beat a red light is worth the risk.The brain never stops changing, but scientists once thought the maturation of the prefrontal cortex from childhood to adulthood was nearly complete by the age of 13. Maps of the brain created through magnetic resonance imaging suggest the development of some functions may continue a decade beyond adolescence, maybe longer."Personal behavior and control and inhibition are indeed some of the parts of the brain to show later development," said Toga, involved in research that tracks brain development from birth to death. "Those circuits that live there have a dramatic influence on how we behave as social animals."People are born with more brain neurons that share information with each other than they need. As the brain matures, it weeds out connections that aren't needed, meaning voices shouting several messages at once become more of a chorus.As the gray matter is pruned, a fatty tissue called myelin is added to the brain. It coats the connection between neurons in insulation that allows thoughts and emotions to be processed faster.In teens, the connections are still being developed between parts of the brain that deal with feelings and logical thought, said Monique Ernst, a psychiatrist and researcher with the National Institute of Mental Health. She theorizes anger, fear and other emotions may pulse stronger. Restraint may be more muted.Ernst said it's not clear if the still maturing pathways in the brain could push teens toward violence. She said she believes people who already have violent tendencies may have more difficulty controlling themselves.(Contact Tom Kisken of the Ventura County Star in California at tkisken(at)venturacountystar.com)