Th 1011

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Th 10/11
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Adverse Outcome Due to Prenatal Rubella (From
Alford, Pass, and Stagno, 1983) 30 of infants
are symptomatic at birth Heart
Defects Microcephaly Deafness Growth
Retardation Retinopathy Cataracts
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Rubella continued Of those symptomatic at birth,
80 show neurobehavioral problems in
childhood Hearing loss Language
disorders Visual abnorm. Motor
disorders Hormonal abnorm. Cognitive
dysfunction Dental Defects Emotional disorders
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Rubella continued Of the 70 of infants who are
not symptomatic at birth, 70 show Hearing
loss Language disorders Visual abnorm. Motor
disorders Hormonal abnorm. Cognitive
dysfunction Dental defects Emotional disorders
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Teratogenic Effects of Radiation

• Mental retardation
• Highest risk during major neuronal migration, at
  8-15 weeks. Incidence increases with dose. At 1
  Gy fetal dose, 75 experience severe retardation
• At 16-25 weeks, fetus shows no increase in mental
  retardation at doses lt 0.5 Gy
• IQ - Risk factor associated with diminution of IQ
  is 21-33 points at 1 Gy to fetus on 8-15 weeks.
• Microcephaly
• observed in 30 children of 1000 exposed in
  Hiroshima and Nagasaki pregnant women
• the effect lt0.3 Gy is not significantly
  different from control

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• Accutane pill used to treat cystic acne
• a synthetic Vitamin A (a retinoic acid)
• isotretinoin

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• Embryonic (14-60 days) Exposure to Accutane
  (Isotretinoin)
• Spontaneous Abortion (40)
• Major Malformations (35)
• Prematurity 16

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• Accutane interferes with the development of
• Central Nervous System
• Craniofacial structures
• The Heart
• The Thymus and Parathyroid Glands
• Other organ systems

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Figure 1. Mental ability of children exposed to
isotretinoin during embryonic development.
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• Is vulnerability to the CNS effects of retinoic
  acid seen in adolescence?
• controversial human data suggest that some
  individuals of unspecified ages may experience
  depression, suicidality, or psychosis following
  Accutane treatment (Wysowski, Pitts, and Beitz,
  2001 Bremner, 2003)
• long term effects are unknown
• 2 studies in adolescent mice show that 21 days
  of treatment with 1 mg/kg/day 13 cis RA reduces
  hippocampal cell survival (Sakai et al, 2004) and
  reduces spatial learning (Crandall et al, 2004)
• reduced hippocampal neurogenesis has been shown
  in depression (increased during antidepressant
  treatment)

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• Prenatal Exposure to Anticonvulsant Medications
• Major malformations
• Craniofacial Abnormalities
• Digit Hypoplasia
• Reduced learning ability

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Underdeveloped nails and final digits of fingers
Digit hypoplasia
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• Diagnosis of Fetal Alcohol Syndrome
• Minimal criteria
• Abnormalities in three areas
• Prenatal and/or postnatal growth retardation
• Central nervous system involvement
• Characteristic facial dysmorphology

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When criteria for effect are just disturbances in
CNS function, affected is much higher.
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CNS Dysfunction Infants feeding problems
sleep problems irritable difficult to soothe
abnormal muscle tone Permanent reduced
intelligence behavioral abnormalities (reduced
inhibitory control social difficulties
increased activity) Alcohol is the 1
preventable cause of mental retardation.
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What about our own experiences after birth? How
do they influence brain development and
organization?
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Enrichment studies by Rosensweig (1960s)
Greenough (1970s - current) Rats raised in
enriched vs impoverished environment --gt
different brain characteristics
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Figure 18.4 Experimental Environments to Test
Effects of Enrichments on Learning and Brain
Measures (Part 1)
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Figure 18.4 Experimental Environments to Test
Effects of Enrichments on Learning and Brain
Measures (Part 2)
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Enrichment studies by Rosensweig (1960s)
Greenough (1970s - current) Rats raised in
enriched vs impoverished environment --gt
different brain characteristics Enriched
heavier brains thicker cortex more
capillaries more proteins more glial
cells larger synaptic fields
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• Enriched experience
• Promotes better learning and problem solving
• Aids recovery from conditions such as
  malnutrition
• May protect against age-related declines in memory

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How are neurons changed due to experience? Hebbs
Rule (1949) - hypothesized that the cellular
basis of learning involves strengthening of a
synapse that is repeatedly active when the
postsynaptic neuron fires
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• How the environment organizes brain development
• Hormonal Influences
• What is a hormone?
• Chemicals used by the endocrine system to
  influence bodily systems, neuronal activity, and
  behavior

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Cells communicate by chemical signals. Neurotransm
itters - chemicals secreted from a neuron into a
synapse causing changes in postsynaptic
neuron Hormones - chemicals secreted by
specialized cells (neurons secretory cells in
glands) into the bloodstream where they are
carried to other parts of body Neurons and
certain cells in Endocrine glands - contain
specialized cells that secrete hormones
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• How do hormones work? A lot like
  neurotransmitters.
• Nervous System uses neurotransmitters to
  directly influence neuronal activity and behavior
• Endocrine System (part is in nervous system)
  uses hormones to directly and indirectly
  influence neuronal activity and behavior, as well
  as other bodily systems.

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Similarities between hormones and
neurotransmitters (nt) 1. Hormones are produced
in endocrine cells and stored there for later
release (just as nt stored in neurons) 2. Hormone
release must be stimulated by receptor activation
(just as nt activate receptors) 3. Hormones bind
with specific receptors (nt bind with specific
receptors)
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Similarities between hormones and
neurotransmitters 4. Hormones bind with
receptors on surface or inside cells (nt
receptors are on surface membrane) 5. Binding
triggers activities within the cell. 6. Some
overlap between cells and substances that
release/serve as hormones and as
neurotransmitters. 7. Drugs/chemicals, diet,
behavior can alter hormone levels and effects
(just as these can alter nt).
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Differences between neurotransmitter and hormonal
actions 1. NTs travel over synaptic space to
receiving neuron Hormones travel in blood to
different locations throughout body where
receptors exist. 2. Hormonal communication is
slower (seconds to minutes) than
neurotransmission (milliseconds) 3. Final
neuronal response to nt is the all-or-none action
potential Response to hormones can be graded -
minimal to major effects (with seasonal and daily
rhythms in thresholds). 4. Can more easily
voluntarily control many neural events harder
for hormonal ones (more reflexive).
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Body has many endocrine glands (collections of
secretory cells) In skull Pituitary Pineal
Hypothalamus In body Thyroid Thymus
Adrenal Kidneys Pancreas GI Tract
(gastrointestinal) Mammary glands
Gonads - testes ovaries
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