Brain development between ages 8 and 25:
A longitudinal study

Adolescence is a highly important transition phase between childhood and
adulthood, marked by significant physical, cognitive, and social-emotional
changes (Dahl and Gunnar, 2009;Steinberg et al., 2008). The onset of
adolescence is characterized by the start of pubertal maturation around the age
of 10 years, during which children undergo rapid physical growth and experience
the onset of sexual maturation (Shirtcliff et al., 2009). One of the most
salient characterizations of adolescence is a steady increase in executive
functioning, or the ability to control our thoughts and actions to make them
consistent with internal goals. Executive functions are thought to be central
to human cognition (Miller and Cohen, 2001), and therefore adolescence can be
seen as a period of significant advancements. However, the transition from
childhood to adulthood is also accompanied by adolescents spending less time
with family, and more with peers. As such, adolescents seek to gain
independence from their parents, establish their individuality, and replace
their parents as their primary attachment figures (Blakemore, 2008).

A fundamental question in the current research proposal concerns how changes
in cognitive and social-emotional behavior are related to functional and
anatomical brain development. The current proposal has the objective to (a)
understand the neural mechanisms behind key developmental transitions in
adolescence using functional MRI, (b) relate these to biological landmarks:
structural brain development and hormone transitions, and (c) understand how
these functions and neural underpinnings develop relative to each others within
individuals (i.e. examine the longitudinal trajectory of development rather
than a snap shot in development). An additional objective is to collect genetic
information for a subset of genes, to examine to what extent individual
differences in brain development can be attributed to genetic differences
between individuals.

The proposed research will be double blind. All subjects will be coded; these
codes will be applied for all research measures (MRI-scans, test-battery
performance etc.).
The subjects will perform standard test-batteries of cognition and emotional
decisionmaking. Furthermore, to get an estimate of IQ, a shortened version of
the WISC/WAIS will be applied to the subjects.

The MRI-scans:
1. Structural MRI, to gain information on gray and white matter properties
(volume, density and cortical thickness)
2. DTI, to gain specific information on white matter microstructure and
fibertracking
3. Functional MRI, to gain information on task-related brain activity during
cognitive and emotional decisionmaking.

Pubertal assessment:
1. Participants will be asked to complete three self-report measures of
pubertal maturation. The self-report scales are 1) the picture-based interview
about puberty (PBIP), 2) the Tanner scale, and 3) the Pubertal Development
Scale (PDS: Petersen et al., 1988
2. Participant will be asked to provide saliva and urine samples to test for
testosterone, DHEA, progesterone, estradiol and luteinizing hormone (LH; the
earliest hormonal marker of puberty) levels.

Genes
1. Genetic information will be measured using an easy cheek swab method.

There are no risks concerning this research project.
See also pages 24-27