brain development psyc of violence jen wright. there are a lot of physical changes that happen...
Post on 19-Dec-2015
218 views
TRANSCRIPT
There are a lot of physical changes that happen during the first years of life,
The most important (and dramatic) of which is brain development.
brain development Largest brain/body mass of any animal. Encephalization Quotient (EQ) = 7.4
•Dolphin = 5.3•Chimp = 2.5•Elephant = 1.9•Whale = 1.8
Most development happens outside (instead of inside) the womb•Monkey newborn 70% adult size•Human newborn 25% adult size
Most growth occurs in first 3 yrs•3 yr old 80% adult size
brain development Neurogenesis – proliferation of neurons
through cell division•At peak, 250,000 cells “born” every minute
Synaptognesis – formation of connections•Each neuron forms thousands of connections
•Axons elongate towards specific targets
•Dendritic “tree” increases in size and complexity
•6 mos have 2 x more synaptic connections
Synaptic pruning – elimination of excess synapses•Streamlines neural processing
•Without synaptic pruning, children wouldn't be able to walk, talk, or even see properly.
Myelination – insulating sheath•Happens at different rates into adolescence
•Certain areas are myelinated first
importance of experience Plasticity – brain’s ability to change w/
experience Experience-expectant plasticity
(experiences present throughout evolution)•Economizes on material encoded in genes
•Development will occur within a normal range of environments
•Level of vulnerability in timing•Critical periods
importance of experience Experience-dependent plasticity
(experiences of individual)•Brain sculpted by idiosyncratic experiences
•Brain responsive to richness of stimuli
•Important in development of expertise•More brain resources dedicated to processing
•E.g. musicians’ cortical representation of hands
•Timing may be less important•Sensitive periods
REM sleep – critical for neural development in brain, esp. for activity-dependent development•E.g. visual system
•Facilitates learning/memory Sleep deprivation linked with later
problems•E.g. ADHD, behavior-problems
Babies most at risk of disruption•Premature infants in IC units
•Erratic, abusive environment
What is attachment? Attachment refers to the close,
emotional bond between an infant and his/her primary caregiver.
Orbital-frontal cortex: connects processing of incoming sensory stimulation with internal emotional experiences
Early views of attachment Psychoanalytic Theory (Freud)
•Driven by oral needs during the first year
•Emphasized early experiences on later outcomes
Behaviorist Perspective •Driven by the need for food
•Learns to associate contact with mother with food
•Mother’s closeness continually reinforced
Ethology Rooted in Darwin’s
Evolutionary Theory Focused on the
adaptive value of behavior
Bond necessary for survival
Lorenz (1952) - Imprinting
Primary criticism of these early perspectives Love (i.e., attachment) seen as
secondary to instinctive or survival needs
Harlow believed that the love and affection were central to attachment•necessary for survival
Harlow’s Monkeys (1958) Early work with monkeys Cloth & wire mother
•Only one equipped with feeding apparatus
•Monkeys randomly assigned
•Observed for 5 months Both groups preferred cloth mother
Contact Time with Wire and Cloth
Surrogate Mothers
24
0
6
12
18
21-251-56-10
11-1516-20
Age (in days)
. . . ..
. . . ..
.
.
.
.
.
.....
Infant monkey fed on wire mother
Infant monkey fed on cloth mother
Hours per day spent with wire mother
Hours per day spent with cloth mother
Mean hours per day
Violence papers:•Incorporate my comments
•Expand to begin providing explanations (using the frameworks we’ve discussed so far)•3-4 pages (double-spaced)
•Bring 2 copies (printed and stapled/clipped)
http://www.youtube.com/watch?v=hsA5Sec6dAI
http://www.youtube.com/watch?v=caM4-f6ZZBE&feature=related
mirror neurons Found in the frontal and parietal lobes Fire when you
•engage in an activity (reaching out one’s hand)
•observe someone else engaging in the same activity.
Fire more strongly when action has some purpose or content •reaching out one’s hand for a cup.
MN’s play a clear role in learning/imitation. May also play a role in “mind-reading”
•grasping intentions, goals, desires.
crying Crying – infant form of
communication•Response to distress
•Development of emotional self-regulation
•Mastery of environment – agency
•Biofeedback loop
When an infant’s needs are met, they are able to turn their focus to the world around them and explore.•Their brains take in and adapt to
stimulation from the external world. When they aren’t met, they become
fixated on trying to get their needs met•They stop exploring and shut out other
stimulation from the external world.
Prolonged crying expose the brain to high levels of cortisol, adrenaline, and other damaging chemicals.•Damage to hippocampus
•Reduced levels of vasopressin and serotonin
•Reduced levels of emotional regulation
• Impaired memory
• Increased levels of aggression/violence/bullying
• Increased levels of anxiety disorders
stress and brain development
Exposure to excessive stress hormones is bad for brain development.
Early symptoms of PTSD The brain can become incapable of
producing normal stress responses.•Hyper-vigilance (Ghosts in the Nursery)
•Emotional flatness Physical/emotional abuse and neglect can
be equally damaging.
emotions and cognition: bi-directional
Emotional reactionsLimbic systemo amygdala/hippocampus link
o Lead to learning that is essential for survival
Influence how a situation is perceived, interpreted, and remembered.
o Improve memory of evento Highlight issues of importanceo Make things personally
relevant
o Create life-long positive/ negative associations
emotional self-regulationStrategies learned for adjusting emotional state to a
comfortable (adaptive) level of intensity in order to accomplish goals.
Sympathetic: child more easily soothed,more interestedmore self-regulated
Non-responsive (wait to intervene): child enters into rapid, intense distressharder to soothedoesn’t develop self-regulation
temperament Constitutionally based individual
differences in •Emotion
•Motor function
•Attentional reactivity
•Self-regulation Influences the way that children
develop, display, and control emotions Foundation for later personality
Temperament styles Types
•Easy
•Difficult
•“Slow to warm up” Differences in punishment/reward Differences in sociability Bi-directional issues
•Gender
•Cultural differences
•Goodness of fit (with parents/environment)
Gene/Environment InteractionTwo levels of environmental influence:
Environment
Genes: Genotype
Genes: Phenotype
Gene/environment interactions
Passive genotype-environment correlation. Evocative genotype-environment correlation. Each child’s genes elicit other people’s
responses, and these responses shape development. • In other words, a child’s environment is partly the
result of his or her genes. Active genotype-environment correlation. Children, adolescents, and especially adults
choose environments that are compatible with their genes (called niche-picking), • thus genetic influences in adulthood increase.