Unit 4 (Part 1): Impact on the Developing Brain

Normal brain development

A "bottom up" process: begins with the most primitive functions and concludes with the most complex

Synapse formation in early childhood

Neural connections form at an alarming rate from 0 to 3 years

Pruning

Synapses are strengthened or discarded based on the child's learning and experiences

Myelination

Formation of an insulating sheath around brain cells that makes nerve impulse transmission more efficient; also "bottom up" and influenced by experience

How long the brain keeps developing

Into young adulthood (mid-20s)

Teen brain changes

Synaptic pruning occurs and white matter increases

Why adolescents show poor impulse control and risk-taking

Frontal lobe development lags behind physical development, so they use lower brain areas

Adolescent limbic system vs. cortex

Limbic system (emotions) is growing while the cortex (reason, abstract thinking) is underdeveloped, leading to emotion-based interpretations and reactions

Young adult brain change

Myelination increases, speeding up neural processing

"Neurons that fire together wire together"

Helps explain the long-term impact of nurturing vs. traumatic experiences in infancy

Neuroplasticity

The brain is adaptive; a protective factor from trauma's impacts and the basis for potential healing

Memory formation

Experiences strengthen neuron pathways, become encoded and eventually become memories; responses become more automatic

Implicit memory

Unconscious perception of the environment and recall of experiences; babies are born with this capacity

Explicit memory

Conscious memories tied to language; develops around 2 years of age

Trauma's impact on brain development

Changes to brain structure and activity, leading to altered emotional and behavioral functioning

Factors influencing trauma's impact on the brain

Age at trauma, single incident vs. chronic, type and severity of abuse, abuser's role/identity, supports/attachment figures, intervention

Age as a severity factor

Earlier trauma tends to have more severe impacts

Abuser's role as a severity factor

Matters when trauma is interpersonal (e.g., attachment figure vs. stranger)

Intervention as a severity factor

Support, treatment, or removal from the traumatic situation

Cortex

The "rational" outer layer of the brain; communicates with the limbic system

Trauma's impact on the cortex

Decreased cortex activity

Why the prefrontal cortex can't help a child under threat

The limbic system activates before the less-developed prefrontal cortex can "weigh in"; staying in fear mode blocks problem solving and learning

Limbic system

The "emotional" brain; controls fundamental emotions and survival instincts; contains the amygdala and hippocampus

Trauma's impact on the limbic system

Increased limbic system activity

Limbic system response to threat

Initiates fight, flight or freeze

Amygdala

Processes emotions and instigates hormone release based on emotional responses such as fear

Amygdala after trauma

May remain activated and continue to sound an alarm inappropriately

Hippocampus

Processes information, gives time and spatial context to memories/events, and transmits information to the cortex for interpretation

Trauma's impact on the hippocampus

Decreased volume

Stress hormones and the hippocampus

Stress hormones from the amygdala's alarm suppress the hippocampus, so information isn't passed to the cortex

Result of hippocampus suppression

Situations are misinterpreted as threats and the limbic system overreacts (fight/flight/freeze)

Decreased hippocampal volume is correlated with

PTSD and depression

Corpus callosum

The "information pathway" between the right and left hemispheres

Trauma's impact on the corpus callosum

Smaller in abused children, giving less hemispheric integration and possibly greater mood fluctuations or personality changes

Neuro-endocrine system

Interaction between the brain and the body's hormones; regulates mood, stress responses, immunity and digestion

Neuro-endocrine response to toxic stress

A ripple of hormonal changes

Chronic neuro-endocrine dysregulation

Linked to prolonged trauma exposure; a significant factor in many of trauma's long-term effects

Cortisol after childhood abuse

Altered cortisol production in both children and adults who experienced childhood abuse

Prenatal stress and cortisol

A stressful prenatal environment may alter cortisol levels

Hyperarousal after trauma

Heightened nervous system activation floods the body with cortisol and stress hormones; can continue long after the trauma

Low cortisol effects

Decreased energy (affecting learning and socialization) and increased risk of autoimmune disorders

High cortisol effects

Cognitive problems, mood problems and reduced immune response

Trauma's impact on memory and worldview

A traumatic early environment can create memories that negatively affect perception of the environment and worldview throughout life

Trauma's impact on explicit vs. implicit memory

Explicit memories may be hard to retain or access, but implicit memories of the trauma remain

Result of retained implicit trauma memories

Nightmares, flashbacks and other responses

Epigenetics

Looks at the biological mechanisms that switch genes on and off

Life events and genes

Can cause genes to be silenced or expressed over time

Child maltreatment and epigenetics

Evidence suggests it can cause epigenetic modifications that can be passed down to future generations

Can epigenetic effects of childhood trauma be corrected?

Yes, by positive changes in environment and experience

Why epigenetics matters for trauma

Helps explain prenatal risks and intergenerational trauma transmission