ADOLESCENT BRAIN: ARTICLES SUMMARIES
WEEK 1: The social re-orientation of adolescence: a neuroscience perspective
on the process and its relation to psychopathology
There enodes mediating social information processing
There are three nodes that are involved in processing of the information. Generally, information in these
nodes is processed in a sequential manner. However, the nodes do not work in isolation but they function
as an interaction network.
For example, efforts to monitor the frame of mind of another individual requires interaction between
perceptual processing of the detection node and cognitive framing that occurs in the cognitive-regulatory
node.
Detection node
This node is dedicated to categorizing a stimuli as social and deciphering its basic social properties.
Structures
- Inferior occipital cortex
- Inferior regions of the temporal cortex
- The intraparietal sulcus
- Fusiform face area (in fusiform gyrus)
- Additional region along superior temporal sulcus (STS)
Function
- Region along STS for biological movement
- Anterior portion of temporal cortex implicated in social recognition
- Regions of these areas are involved in perceptual functions. Determining whether a stimulus is
animate or not, whether it is conspecific, what it is doing or intends to do and what individual
identity is
Affective node
Structures
- The ones involved in reward and punishment
- Bed nucleus of striatum terminalis
- Amygdala
- Ventral striatum
- Septum
- Hypothalamus
- Under some conditions orbitofrontal cortex
Function
- In OFC stimuli is imbued with emotional significante
- Determines whether stimuli should be approach or not
- Modulates various autonomic and cognitive processes (like cardiovascular control, attention
allocation)
,Cognitive -regulatory node
Structures
- Dorsal prefrontal cortex
- Medial prefrontal cortex
- Portion of Ventral prefrontal cortex
- Portion of Orbitofrontal cortex
Functions
Three basic processes occur in this node:
1. Perceiving the mental state of other individuals (TOM)
These processes are drive by paracingulate area of dorsomedial prefrontal cortex
2. Inhibition of prepotent responses
As regulated by ventral prefrontal cortex
3. Generation of goal directed behavior
Goal behavior relies on the interaction between the dorsal and ventral prefrontal cortices.
Ventral prefrontal cortex plays a role in both affective attributions and cognitive representations and
regulation of affective responses.
Developmental changes in the SIPN during adolescence
Three prominent changes during adolescence are:
- The emergence of sexuality,
- An increase in peer orientation,
- Decrease in parental and family orientation
Changes in affective node
The regions that make up the affective node are densely innervated by gonadal steroid receptors and
undergo both functional and anatomical reorganization during puberty. Gonadal steroids alter brain
functions in a variety of ways, one of which is to regulate other neurotransmitters.
At the behavioral level, there is clear evidence from both human and animal studies that gonadal steroids
alter responsiveness to social stimuli. Evidence of this is effects of androgenes on sex reponsivness. In
both males and females, higher levels of androgen in circulation result in increased capacity of a social
stimulus to elicit urges for sexual approach. Also affective responses elicited by male faces varies across
the menstrual cycle in women, presumably reflecting the influence of fluctuating levels of gonadal
steroids in the central nervous system.
Gonadal steroids may influence the affective attributions that are made to social stimuli within the SIPN
and the affective node is likely the primary site of action for these hormonal effects. Gonadal steroids
exert strong influence on social processes, such as exual behavior, maternal behavior, social bonding, and
social memory
In general, these hormonal effects are mediated by functional changes in the affective node that are
indirectly related to gonadal hormone levels in circulation. For example, circulating levels of estrogen can
increase oxytocin receptor density within the amygdala, septum, nucleus accumbens, and bed nucleus of
,the stria terminalis of female rats, and the oxytocin receptor density in these regions may be related to the
amount of nurturant behavior bestowed upon infants.
Hormonal effects are most important during initial encounters with a novel stimulus, and after behavioral
patterns have been established they become relatively independent of hormonal manipulations. This
suggests that the adolescent period may be a particularly important and malleable one in establishing
patterns of social behavior. Thus gonadal hormones have important effects on how structures within the
affective node respond to social stimuli, and will ultimately influence the emotional and behavioral
responses elicited by a social stimulus during adolescence.
Changes in cognitive-regulatory node
Individuals with damage to this area have impairments in social awareness and social decision
making and often have psychopathic behavioral tendencies. Damage in early development →severe
dysfunctions in social cognition seem and may interfere with the ability to generate abstract
knowledge about appropriate social and moral expectations.
Potions of the prefrontal cortex, including orbitofrontal, ventrolateral, and medial prefrontal region, do
not reach maturity until early adolescence, typically in the late teens or early twenties. performance on
tasks that require inhibitory control, such as the go–no go paradigm, does not plateau until mid to late
adolescence, and behavioral performance on such tasks is related to both functional and morphometric
development in the prefrontal cortex.
Changes in this node are not closely related to gonadal hormones. Development that does occur here is
the result of myelination and pruning of existing synaptic networks. Pruning is similar to learning, Since
it involves survival of local network connections through competitive, use-dependent strengthening.
Nature of pruning, therefore, facilitates the incorporation of experience into neurobiological development.
Changes in cognitive nodes are therefore slow, iterative, and independent of hormonal states. However,
interaction between the affective and cognitive nodes may result in secondary effects of hormones within
the cognitive node.
What can neuroimaging tell us about developmental alterations in the SIPN?
The surge of gonadal hormones during puberty alters the emotional processing of social stimuli, as
instantiated in the affective as opposed to the detection or cognitive-regulatory nodes. Maturational
changes and experience alter the brain’s ability to regulate responses to social stimuli and integrate them
into a larger framework.
Study: differences between adolescents and young adults in activation patterns in both the affective and
the cognitive-regulatory nodes while processing social stimuli
While passively viewing faces with fearful emotional expressions
, Results: Adolescents exhibited greater activation than adults in the amygdala, orbitofrontal cortex,
and anterior cingulate → finding suggests that when attention is unconstrained, adolescents may be
more sensitive to the emotional properties of a social stimulus.
When subjects were asked to switch their attention between a salient emotional property
of the face and a non-emotional property. Adults, but not adolescents, were able to selectively engage and
disengage the orbitofrontal cortex. These findings highlight interacting, developmental alterations in both
the affective and cognitive-regulatory nodes of the SIPN.
Other changes that are expected to take place in affective node during adolescence:
- Peers should be perceived as more rewarding in middle and late adolescence than in late
childhood, and the reverse pattern should emerge with parents.
- Adolescence progresses, cues of peers would induce increased activation in the affective node.
This enhanced affective processing would also probably exert stronger influences on attention
and memory process
- Opposite sexed peers should be afforded greater approach value and cognitive resources than
same-sexed peers (at least in heterosexual youth)
- Hypersensitivity to acceptance and rejection by peers during adolescence. It was hypothesized
that activations associated with motivation, self esteem, acceptance and rejection in a social
context will be augmented in the affective node of the SIPN during the adolescent period, and
extreme activation may be related to psychopathology
It is predicted that changes occur in cognitive regulatory node too:
- When exposed to hostile or fearful faces, young adolescents are less able to modulate activity
within the affective node of the SIPN under varying task demands than are adults → this
suggests that developmental changes occur in the ability to regulate responses to social
stimuli a process we have ascribed to maturation of the cognitive-regulatory node
- Region in the dorsomedial cortex is central to the ability to take someone else's perspective and
this region continues to undergo changes well into late adolescence or early adulthood.
Brain development, SIPN, and affective disorders
The incidence of affective and specific anxiety disorders rises dramatically during adolescence
(depression, social phobia, and panic disorder). For development of psychopathology changes in the
processing of social stimuli within the SIPN may be particularly important. That is because:
1. Adolescence clearly represents a period of heightened emotional responsiveness to social stimuli
and socially related events
- In some individuals the strong emotions cross the line from normalcy into psychopathology. The
intensified emotional potency of interpersonal interactions during this period may result in
heightened sensitivity to negative interpersonal events which may be particularly relevant to
psychopathology.
- Rejection by romantic partners and peers:predictor of behavioral and psychiatric difficulties
during adolescence, including initial depressive episodes, substance use and externalizing
behavior.