The Adolescent Brain - Uitgebreide college samenvatting - Extensive summary of all lectures (English)
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The Adolescent Brain (6463PS030Y)
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Universiteit Leiden (UL)
This is an extensive summary of all lectures! Een uitgebreide samenvatting van alle hoorcolleges die goed aansluit op de literatuur en oefentoets. Vrijwel het hele college is uitgetypt in een paar pagina's, wat het herhalen van de colleges makkelijk en snel maakt. De samenvatting is in het Engels o...
The Adolescent Brain Lectures
Lecture 1 – Adolescent Development from a Neuroscience Perspective ................................. 2
Lecture 2 – Emotion Regulation ............................................................................................... 8
Lecture 3 – the Social Brain.................................................................................................... 12
Lecture 4 – Social Decision-Making in Peer Context ............................................................ 17
Lecture 5 – Puberty and Brain Development .......................................................................... 23
Lecture 6 – Reinforcement Learning ...................................................................................... 28
Lecture 7 – the Developing Brain and Problem Behaviors .................................................... 34
Summary of Brain Regions and Their Functions ............................................................... 40
, Lecture 1 – Adolescent Development from a Neuroscience Perspective
Functional Magnetic Resonance Imaging (fMRI)
You can get different types of images with the MRI scanner; you can look at the anatomy to
inspect the brain structure (with MRI), but you can also see brain function and activity
with fMRI. So, fMRI is a special MRI technique to measure brain activity.
Since the MRI is a huge magnet, there cannot be any magnetic things in the room. When the
participant is doing a task, usually there is a screen in a different room, and the participant
will watch the reflection of the screen in a mirror. Usually, the participant has to respond,
either with buttons or a joystick. The participant will be provided with earplugs and
headphones because the machine is very loud.
You cannot take a picture of the whole brain at once, so you scan different slices of the
brain. It takes 2 seconds to scan the whole brain through slices. You have to correct for the
slices in the analysis → the average is taken.
fMRI is an indirect measure of brain activity, which causes it to be slow. The idea is that,
when a brain area becomes active, it needs oxygen. This oxygen flows to active brain regions
through the blood. fMRI is a measurement of blood flow: it measures increased blood flow.
In blood, oxygen is connected to hemoglobin, which has magnetic properties. So,
hemoglobin makes it possible to measure activity with magnetic resonance.
BOLD-effect (Blood Oxygenation Level Dependent): neural activation requires oxygen,
which is provided by blood, which results in a stronger fMRI signal. So, the fMRI is picking
up the increase in blood flow!
EEG vs fMRI
In EEG, participant wear a cap with electrodes, which pick up brain activity signal. EEG has
a high temporal resolution (in ms), but low spatial resolution. A disadvantage of EEG is
that it the measured signal only comes from the surface of the brain. Therefore, it is not
possible to measure activity in subcortical brain areas. Since the temporal resolution is
high, EEG is often used to examine processes that are fast, such as language, hearing or
speaking.
EEG is faster, has higher temporal resolution, but lower spatial resolution. fMRI is a
non-invasive technique, which has a high spatial resolution (in mm), but a low temporal
resolution (more than 5 seconds).
In fMRI studies, there usually are at least 2 conditions: control and experimental (for
example faces versus houses; or faces versus scrambled faces). For every condition, there
should be at least 10 to 15 trials in an fMRI task. The more trials, the stronger the signal
(more power).
It is important to have a good control condition, to make reliable conclusions of what
the brain activity means.
2
,You average the BOLD signal across all the trials of the condition → you get a signal for the
condition (e.g., a signal for ‘faces’, and a signal for ‘houses’). The contrast could be: faces >
houses, so: stronger BOLD signal for faces compared to houses. You subtract the house
signal from the faces signal.
Each slice is divided in voxels (cubes), and you will get a signal for each voxel.
Keep in mind: the BOLD signal is not an absolute measure of brain activation, but it is
relative. A control condition is crucial because the BOLD signal is not an absolute measure.
There should be many trials per condition (at least 20). There should be fixation between the
trials, for example a little cross in the middle of the screen as a fixation point. It is important
to keep the participants engaged while doing the task (e.g., requesting a button response).
Brain Development in Adolescence
Adolescence: the transition from childhood to adulthood. Adolescence starts with the
hormonal changes related to puberty (ages 8 – 10). The age of which you become an adult
differs per culture. In the Netherlands, by law, someone is an adult at age 18.
Structural changes take place from birth to adulthood. There is an increase in connections
between neurons (this increases the strength of connections), and there are also more
neurons and more white matter. Also, there is an increase in myelination in the cortex,
due to the increase in connections (myelinated axons). Gray matter decreases across
adolescence.
The change in gray matter is due to 2 processes:
• Synaptogenesis: increase in synapses. Synapses are between neurons, here the signal
is passed from neuron to neuron. This is the increase in gray matter at a young age.
• Pruning: elimination of excess synapses. Synapses that are not used are eliminated,
which explains the decrease in gray matter during adolescence.
There are different trajectories across brain regions!
In this picture, you can see the decrease of gray
matter in different brain areas. The more purple,
the more cortical thinning → less gray matter.
Overall, there is less gray matter in the brain
with age. However, some parts are more purple at
earlier age (e.g., occipital lobe → visual part, this
matures earlier than other brain regions). The
latest areas to mature are the frontal areas and the
temporal areas.
3
, Anatomical terminology
These terms are used to locate brain areas.
Paper Discussion: Neuroscientific Models for Understanding Adolescence Development
Nelson and colleagues (2005) model, the Social Information Processing Network, is used
to understand the dramatic changes in social behavior in adolescence (social re-orientation).
With this model, they propose that there are 3 different nodes (networks) of brain regions.
The nodes are all different in terms of developmental pace and their functions. There is some
type of sequentiality in how the networks are involved in social decision making in
adolescence. The model helps us to understand how the brain functions in social situations
across adolescence and how the brain responds to social context.
The first node is the Detection Node, which is engaged in perceptual processing. The green
brain regions are involved in processes like face perception, facial expressions and emotions
→ fusiform face area, superior temporal sulcus, anterior temporal cortex. These
processes are important in social interaction. But also, more simple aspects of social
interaction, like biological motion (detecting whether something is alive or not) and other
sensory modes. In 2016, the paper was revised and the Temporal Parietal Junction was added
to the DN (more higher order functions). The DN is the first node to mature!
4
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