Hazard anticipation of young novice drivers - SWOV

peaks at 16.7 years of age in girls and at 16.2 years of age in boys. Parietal
lobe cortical gray matter peaks at 10.2 years of age in girls and at 11.8 years
of age in boys. After a peak in a lobe, the volume of gray matter gradually
declines. The DorsoLateral Prefrontal Cortex (DLPFC) is in particular slow in
loss of gray matter and continues to lose gray matter well into the third
decade of life (Giedd, 2004). The DLPFC is a region of the Pre Frontal Cortex
(PFC) and is involved in impulse control, judgment, planning and decisionmaking.
The PFC that consists of various sub-areas such as the DLPFC is
essential for what are called the executive functions. Executive functions
refer to the regulation of planning and social behaviour in situations when
'automatic' responses are inadequate such as when persons are planning
tasks, weighing risks and other tasks related to decision making. The
executive functions and the PFC are discussed in more detail in Chapter 3.
Decline in gray matter is associated with 'dendritic and axonal arborisation'.
This process is also referred to as 'synaptic pruning'. A reduction in gray
matter is not a symptom of the decay of the brain, but of the development of
the brain; it helps the brain to operate more effectively. In contrast to white
matter, gray matter contains neural cell bodies and mostly does not contain
myelinated axon tracks. The neurons in cortical gray matter process the
information originating from the sensory organs or process information from
other gray matter (e.g. information from long term memory) in order to
create a response to stimuli from the sensory organs or other gray matter.
Dendritic and axonal arborisation (synaptic pruning) makes this information
processing more effective. Especially the late maturation of the PFC and in
particular the late maturation of the DLPFC have tentatively been associated
with the high crash rate of young novice drivers (e.g. Isler, Starkey, & Drew,
2008).
Brain function during adolescence
Casey, Getz, & Galvan (2008) noted that risk-taking during adolescence is
probably not solely the result of the late maturation of the PFC. Although
subcortical areas do not seem to mature markedly during the second half of
adolescence (the period in which adolescents start to drive), certain
subcortical areas in adolescents show different activities (increased activity
or decreased activity) compared to adults when participants of both groups
have to perform tasks such as gambling tasks when situated in an MRI.
Research in which participants have to perform task that do not require head
movements while situated in an MRI, is called functional Magnetic
Resonance Imaging (fMRI). In fMRI use is made of the fact that oxygen in
blood changes the magnetic resonance slightly. An area of the brain that is
27