brain development and toxic stress

Brain Development and Toxic Stress

Jordan Greenbaum, MDStephanie V. Blank Center for Safe and Healthy ChildrenChildren’s Healthcare of Atlanta

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Basics of Brain Development• Most neurons present at birth• From birth to 5 years, brain triples in

mass• Growth involves connections

http://upload.wikimedia.org/wikipedia/commons/c/c4/Neuron-figure.svg

Brain Maturation

Location is everything!

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Sensitive Periods

• Windows of opportunity

– Effects of experience on brain are very strong

– Vary with area of brain

– Initial experience is more influential

• Plasticity persists (it’s never too late!)

http://images.google.com/imgres?imgurl=http://www.mhsks.org/assets/clientPhotos/Infant.jpg&imgrefurl=http://www.mhsks.org/cdservices.cfm&usg=__QmfDoxMBazsft3y36pnuyJMODkk=&h=1024&w=1024&sz=93&hl=en&start=2&tbnid=GgBi3R7_n8L44M:&tbnh=150&tbnw=150&prev=/images%3Fq%3Dinfant%26gbv%3D2%26hl%3Den%26safe%3Dstrict%26client%3Ddell-usuk%26channel%3Dus%26ad%3Dw5

Neural Plasticity

• Continues to a certain extent throughout life

• Decreases with age• Allows us to

compensate for injuries, change behavior, learn

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Some Critical Areas of the Brain

• Emotions and stress response

• Contextual memory

• Executive functions

• Interact with each other

Prefrontal cortex

Let’s Talk About Stress!!

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Hot Spots for the Human Stress Response

prefrontal cortex

cingulate gyrus

Sympathetic Nervous System

Fight

Flight

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Hypothalamic-Pituitary-Adrenal Axis

• Initiated by amygdala

• Cortisol secreted within

minutes

• Effects seen for hours

So, how does this work?

Prefrontal Cortex

(Super ego)

Amygdala(Emotion)

Hippocampus(Facts, ma’am)

Hypothalamus

Pituitary

Adrenal Gland

Brainstem

Arousal,FocusingFFF

Cortisol

Thalamus

KaBoom!

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Toxic Stress

• Toxic stress:

– Strong, frequent or prolonged

– Often uncontrollable

– No supportive adult

http://images.google.com/imgres?imgurl=http://csquaredplus3.typepad.com/.a/6a00e5527bf30888330111689248ce970c-250wi&imgrefurl=http://csquaredplus3.typepad.com/csquaredplus3/2009/02/weekend-update-or-i-got-nothin.html&usg=__7oiRQmNCdrVSro6vJ00acn_A2eY=&h=166&w=250&sz=5&hl=en&start=47&um=1&tbnid=voO2NNOlsVVrRM:&tbnh=74&tbnw=111&prev=/images%3Fq%3Dsad%2Btoddler%26ndsp%3D18%26hl%3Den%26safe%3Dactive%26rlz%3D1T4DKUS_enUS266US266%26sa%3DN%26start%3D36%26um%3D1

• Particularly malleable during fetal and early childhood periods

• Experience influences later responses to stress• Fear conditioning

– Neutral stimulus associated with aversive one that causes fear

– Gradually neutral stimulus comes to elicit fear– Can generalize further to other neutral stimuli

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Stress Response

• Increases fear, stress, anxiety in ‘safe’ situations

• Impacts social interaction, behavior, learning

• Prefrontal cortex damage is key• Can occur even in infants• Removing the danger doesn’t ‘fix’ the

child

Generalized Fear-Conditioning

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Prefrontal Cortex

Amygdala

Hippocampus

Brainstem

Arousal,FocusingFFFPrefrontal

Cortex

Amygdala

Cortisol

Pituitary

Hypothalamus

Hippocampus

Effects of Chronic Stress

Adrenal Gland Cortisol

My contact info:Jordan Greenbaum, MDCell: [email protected] anytime!

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