L3: Brain Development in Adolescence Flashcards
(23 cards)
Define gray matter and explain its role in brain development
- Gray matter: outermost layer in the brain composed of neuronal cell bodies
- Related to cortical thickness
- There is overproduction at the start of puberty, followed by rapid synaptic pruning during adolescence
- Overproduction: rapid increase in the production of synaptic connections in the brain
- Synaptic pruning: process by which the number of synapses in the brain is reduced
- Gray matter develops as a function of the environment and experience (“use it or lose it”)
How do changes in gray and white matter in adolescence influence the brain?
It helps cortical processes become more efficient but less flexible/adaptable
Describe how the environment influences gray matter
- Gray matter develops as a function of experience (“use it or lose it”)
- Lower SES is associated with less gray matter. This is because these people experience less enriching environments and therefore have less experiences, resulting in a greater rate of synaptic pruning
Describe how the environment influences white matter
Myelination is relatively experience independent
Define white matter and explain its role in brain development
- White matter: inner layers of the brain composed of myelinated axons
- Related to structural connectivity
- Myelination occurs independent from experience
- Increasing volumes of white matter until the 40s
Define overproduction
- Overproduction: rapid increase in the production of synaptic connections in the brain
- Occurs around the onset of puberty
- Results in increased gray matter volume
Define synaptic pruning
- Synaptic pruning: process by which the number of synapses is reduced
- Occurs after period of overproduction
- Helps to make neural processes more efficient
- “Use it or lose it”
Explain the Dual Systems Model
- The Dual Systems Model posits that (risk-taking) behaviour in adolescence stems from an imbalance in brain systems
- Earlier maturing emotional system (limbic) vs later maturing cognitive control system (PFC)
- This results in reduced impulse control and emotion regulation
Explain the Triadic Model
There is an imbalance between the:
* Cognitive control system (PFC)
* Reward/approach system (VS)
* Emotional system (Amy)
Adolescents are more sensitive to rewards and emotional stimuli, and there is little top-down regulation of this.
* Adolescents show heightened activation of the VS (reward) when receiving rewards in an experimental setting
* Adolescents show heightened activation of the VS in no-go trials for happy/fearful faces (vs neutral faces)
List the systems of the social information processing network
- Cognitive control system (dlPFC)
- Reward/affect system (VS, Amy)
- Social cognition system (mPFC, TPJ)
What is the function of the social information processing network?
- Detection of salient information in the environment
- Assigning value to information
- Social cognition
- Use of information to guide learning and behaviour
Define social sensitivity
Shifting motivation towards social relatedness, which intensifies the attention, salience, and emotion regulated to processing information concerning social evaluations and social standing
What happens to the socioaffective circuit in adolescence?
It becomes more sensitized, which causes greater detection and responses to salient social cues
Provide examples of how the socioaffective circuit is more sensitized in adolescence
There is greater sensitivity to social evaluation
* Embarassment peaks in (early) adolescence. When told that a camera would be turned on and peers would view them, there was greater activity in the mPFC, which is related to self-directed thought
There is greater value put on other peoples perceptions of oneself
* In Cyberball, explicit social exclusion from peers occur. Compared to adults, adolescents showed more negative emotions and greater activation in the mPFC, implying that they assigned greater value to peer evaluations
Adolescents are more susceptible to peer influence
* In the Stoplight Game, participants must get to the end of the course as fast as possible. When at a red light, the participant can either choose to stop (delay of 3 seconds), or go, which can result in either a success (delay of 0 seconds) or a crash (delay of 6 seconds). When in the presence of peers, adolescents took more risks and crasehd more often.There is greater activation of the VS when peers are present, indicating that adolescents find peer presence more rewarding
* In the Body Image Paradigm, there was greater activation in the insula when there was a discrepancy between the participants evluation and those of their peers. Greater activation of the insula is associated with greater emotional distress, which is associated with greater peer conformity
* In the Power of Like study, there was a greater likelihood of liking a photo if it had a lot of likes, as well as greater activation in the social network
What do mPFC activation levels predict?
- Greater activation of the mPFC is indicative of more value being put on what others think of you
- Greater activation of the mPFC predicts lower resistance to peer influence
Why is there a shift towards prosocial behaviour in adolescence?
- Greater empathic concern
- Increased perspective taking capabilities
- Greater cognitive control
Define prosocial behaviour
Actions intended to benefit others
Describe studies into empathy development in adolescence
- When viewing images of people in pain (intentional or unintentional), the same pain matrix is activated as when you yourself experience pain
- When viewing images of intentional harm, there is greater activation of the emotional system in adolescents, while adults show greater activation of the cognitive control system. This suggests that adolescents’ empathy is bottom-up, while adults regulate empathy in a top-down manner
Define social perspective taking
The ability to infer thoughts, intentions, motives, and attitudes of others
Define role taking
The ability to assume another person’s POV and understand their intentions, thoughts, and feelings
Describe studies into perspective taking changes in adolescence
- In the Ultimatum Game, a proposer chooses how to divide money, and the responder can choose to accept or reject the proposal.
- Across all ages, people are less likely to accept the offer the more unfair it is
- In another experiment, there were two conditions: the proposer could either choose between a fair and unfair offer (fair-alternative) or only choose an unfair alternative (no-alternative). The responder could see the options the proposer could pick from, and then accept or reject this proposal
- With increasing age, people were more likely to accept the unfair offer in the no-alternative condition. This was related to increased activation in the dlPFC (impulse control) and the TPJ (perspective taking). Therefore, perspective taking (TPJ) mediates the relationship between age and rejection rates.
Explain how the role of intentions changes in adolescence
- In another experiment, there were two conditions: the proposer could either choose between a fair and unfair offer (fair-alternative) or only choose an unfair alternative (no-alternative). The responder could see the options the proposer could pick from, and then accept or reject this proposal
- With increasing age, people were more likely to accept the unfair offer in the no-alternative condition. This was related to increased activation in the dlPFC (impulse control) and the TPJ (perspective taking). Therefore, perspective taking (TPJ) mediates the relationship between age and rejection rates.
Describe features of reinforcement learning in adolescence
Method
* In the reinforcement study, adolescents believed that they were receiving notes (positive social reinforcement) from three peers.
* Notes were considered positive social reinforcement because it indicated that the peers read the participants survey about themselves and liked them enough to respond.
* These peers represented 3 conditions, each with distinct probabilities of social reinforcement:
* Rare interaction - notes (positive social reinforcement) on 33% of trials
* Frequent interaction - notes (positive social reinforcement) on 66% of trials
* Continuous interaction - notes (positive social reinforcement) on 100% of trials
Results
* All positive social reinforcement equally motivated adolescents and caused greater activation of the insula, regardless of the expected outcomes (all conditions), indicating that adolescents find all peer approval equally motivating.
* Adolescents had lower positive learning rates (lower reaction times), indicating that they do not really update their beliefs after receiving positive social feedback
