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Teacher’s notes

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This clip shows the implications of research findings on teenage brain development, particularly for the criminal justice system. It begins with a re-enactment of 18-year-old Monica stealing a car without thinking of the consequences, followed by brain development researcher Dr Stephen Wood explaining that the brain’s capacity to control such impulses does not fully develop until the age of 25. Against scenes of street riots, prison walls and the inside of a prison cell, the narrator says that prisons are full of 18- to 25-year-olds and that Monica had been one of them.

Educational value points

• As the narrator Dr Jonica Newby describes, scientists have been amazed by research findings about just how long the brain takes to develop 'behaviour brakes’, far longer than the legal age of adult responsibility – 18 – assumes. The area in the brain that restrains impulsive behaviour is called the dorsal lateral prefrontal cortex and is among the last areas in the frontal lobe area to mature. It is generally not fully remodelled until the age of 25.

• The process of teenage brain remodelling discussed in the clip lasts for more than a decade and involves little-used synapses being pruned away while those in use are strengthened and stabilised by white matter (myelin) wrapping itself around them. Just before puberty there is a marked over-production of synapses in the frontal lobe and this burst of synapses, unrestrained and not yet remodelled, can explain why adolescence is often a time of breaking out.

• Brain research also suggests the reasons that adolescence and early adulthood are times of great risk taking, and in the clip 18-year-old Monica is used as an example of a teenager whose brain had not developed enough to restrain her impulse to steal a car. In a metaphor that resonates with Monica’s joy-ride, some scientists describe the years 12 to 25 as the time that the brain’s accelerator is being pushed to the floor with the brakes not fully operational.

• The age of adult legal responsibility is about halfway through the years of brain remodelling – at 18, offenders pass from the juvenile to the adult criminal justice system and, as in Monica’s case, can go to jail. The narrator explains that the 18–25 age group is greatly over-represented in Australia’s jails. Later in the Catalyst episode Dr Chris Lennings, a forensic psychologist specialising in juveniles, advocates a separate tier to the prison system specifically for 18–25s.

• The clip shows Catalyst's ability to make exciting science accessible to the public. The findings of scientists such as Wood are made real by the fast-paced reconstruction of Monica’s joy-ride at 18, contrasted with her discussion at the age of 24 of how she did not think of the consequences. The narrator clearly identifies the research’s ramifications. The loud music and street sounds accompanying the scenes of teen criminal behaviour reinforce the message.

• Australian science plays its part in international brain research, with the Melbourne Neuropsychiatry Centre at the University of Melbourne where some of the footage was shot, building a reputation for neuro-imaging and neuropsychological work on schizophrenia and psychosis. Dr Stephen Wood is a senior fellow there with a particular interest in brain development during adolescence.