The Adolescent Brain

The Adolescent Brain

1. The Social Information Processing Network (SIPN) by Nelson

   • Three nodes: 1) the detection node 2) the affective node 3) the cognitive-regulatory node
     • The cognitive-regulatory node: • Three basic processes 1) perceiving the mental state of other individuals (TOM) operations]. --> the paracingulate area or dorsomedial prefrontal cortex. 2) the inhibition of prepotent responses as regulated by the ventral prefrontal cortex. 3) the generation of goal-directed behaviors
       • result of increased myelination and pruning of existing synaptic networks, not so much tied to hormonal changes compared to the affective node
     • the affective node : densely innervated by gonadal steroid receptors and undergo both functional and anatomical reorganization during puberty --> At the behavioral level, there is clear evidence from both human and animal studies that gonadal steroids alter responsiveness to social stimuli
     • recent studies have reported abnormalities in SIPN structures in adolescents suffering from mood or anxiety disorders
     • affective and regulatory systems can't be seen as completely separable
   • Study:Passively viewing emotional faces -> amygdala activation
     • Casey's article: Amygdala input to ventral striatum facilitates motivated action + increased amygdala activity to threat cues --> it is possible that the increased impulsivity in adolescents is due to less mature prefrontal top-down regulation of this amygdala input

2. Burnett et al.: The Social Brain

   • Interaction Specialisation theoretical framework: discrete cognitive functions (e.g. facial identity recognition) are an emergent product of interactions between different brain regions, and between the whole brain and its external environment. Age-associated changes in functional brain activity, as described in the article for faces, are hypothesised to reflect emerging task selectivity or ‘fine-tuning’
   • activity within arMPFC, during mentalising relative to control tasks, correlates negatively with age between adolescence and adulthood
     • Change in strategy or shift in regional specialisation?
   • very little is known about the development of mentalising beyond early childhood --> the lack of suitable paradigms
   • Emotional Stroop Task Studies: indicate the ink colour for rejection, acceptance and neutral words -> In adults, vlPFC (regulatory area) activated more in rejection words, whereas in adolescents it activated more to acceptance words
     • prefrontal regulatory mechanisms continue to develop between mid-adolescence and adulthood, and this may be one factor underlying observed adolescent hypersensitivity to rejection
   • Fictitious peer evaluation: age-related increase in vMPFC activity, whereas in mentalizing there is decrease in arMPFC -> arMPFC is related to self-referential processing
   • The developmental mismatch model by Casey et al
     • during the time lag in functional maturity between PFC and limbic regions, individuals are more greatly affected by emotional context (e.g. reward immediacy, anticipated social rejection) when making decisions

3. Crone: Considerations of fairness

   • The Dictator game
   • The Ultimatum Game
   • The Mini-Ultimatum
     • --> the neuroimaging results revealed an age-related increase in activation in the DLPFC and TPJ in the no-alternative condition compared to the fair alternative condition -> These results may indicate that inhibition of selfish impulses and perspective taking continue to develop gradually during adolescence
   • Trust Game
     • In ados < 15, mPFC always active, older than that: only when being selfish
   • • Dorsolateral prefrontal cortex activation has been linked previously to the inhibition of selfish impulses, suggesting a strong interplay between activation in the DMPFC and activation in the DLPFC and TPJ, with negative connectivity in adolescence

4. Casey: Self Control

   • Self-control = the ability to suppress inappropriate emotions, desires, and actions in favor of alternative, appropriate ones
     • Three key brain areas: the amygdala (emotionally significant environmental cues and associative learning), prefrontal cortex (reasoning and regulating), and ventral striatum (learning and prediction of rewards)
       • Interconnections : DA and hippocampal inputs
         • Earlier peak in DA receptor density in Striatum compared to the PFC .--> overreliance on rewards?
           • Anti-saccade task --> if there was a reward for succeeding, adolescents performed better compared to no-reward conditions than adults
   • --> striatum, but also premotor areas activated when having positive peer cues --> motivating towards action?
   • Fear learning: Mostly based on amygdala
     • --> acquisition: CS + UCS, extinction: only the conditioned stimulus (without the UCS) --> reduction of the fearful response --> however: context change/spontaneous change over time: the fear "returns" -> relapses after exposure therapy
       • Ados are more likely to get a "return" of fear despite from extinction learning
         • Schiller et al.: Study in adults! Conditioning -> reminder (10min/6h before or not at all) -> extinction training
     • Cognitive reappraisal
       • increase in PFC area recruitment across age

5. Self-concept & Identity

   • Article by Pfeifer et al.
     • • mPFC --> dorsal areas: cognitive aspects of self-appraisals --> ventral and anterior rostral parts: sensitive to affective and motivational components --> Anterior rostral mPFC (sometimes also referred as arACC) may be strongly engaged by positive, approach-oriented, self-relevant thought such as reflection on hopes and aspirations, first-person perspective-taking --> mPFC appears to support both cognitive and affective and motivational aspects of self-appraisals --> past, present & future
     • MPCC: autobiographical memory, feeling of remembering
     • Mentalizing: TPJ, pSPS
   • Studies
     • Self vs Harry Potter: a well-known fictional other, when adults thought of HP > dmPFC, ACC, adolescents only ACC
       • Ados activated mPFC more than adults: more effort needed?
     • Self vs others, adolescents (14-16) -> a lot overlap between self and friends, vmPFC
     • • Perspective study: Pfeifer --> own perspective & reflective perspectives (e.g. best friends, classmates, mom) --> Adults: mPFC & mPPC (precuneus) in all conditions, TPJ in perspective conditions --> Adolescents: mPFC & mPPC & left TPJ in all conditions --> thinking about others' evaluations also in direct evaluation --> mPFC more active when thinking about mom's perspective on academic traits compared to peers, the opposite pattern in social skills --> the "perspective person" has to be seen as relevant evaluator in the domain
     • For ados it's more rewarding to think social traits from the perspective of others, compared to adults or other traits
     • Friends as a buffer -study

6. Social Decision Making

   • Van Hoorn et al: alone, spectator, evaluation conditions: adolescents only
     • prosocial behavior increased in the presence of peers, and even more when participants received evaluative feedback from peers.
     • Two age groups!!
   • Chein et al.: Simulated driving task
     • Ados, young adults, adults
     • Alone vs peer condition
     • the presence of peers may sensitize the incentive processing system for adolescents
     • PFC less active compared to adults
   • Guroglu et al.: increasing differentation with interaction partners in donation task across age

7. Depression & Problem Behavior

   • • dopaminergic reward system is activated by the anticipation of rewards
     • Increased sensitivity to rewards + PFC maturation: anticipation of rewards, rumination, interpesonal disappointments --> depression
   • Health Paradox

8. Puberty & Hormones

   • Animal evidence: effects on adolescent brain development
     • Social behavior in males doesn't develop normally if testosterone is depleted
     • proliferation of new cells, controlled cell death
     • influencing structural complexity & neural dendrites
   • Testosterone ~risk taking, also more activation in vmPFC while taking risks --> increasing reward values?
   • Study: 300 participants, 8-25 years old --> follow-up study, three time points
     • Many different 'studies' inside the study
     • More testosterone, less connectivity
       • Different pattern in animals & MS!