Lecture 9 - Neurodevelopmental Disorders Flashcards

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1
Q

What are the different stages of brain development ?

A
  1. Cell birth (neurogenesis)
  2. Cell migration
  3. Cell differentiation
  4. Cell maturation (dendrites & axons growth)
  5. Synaptogenesis
  6. Cell death (apoptosis) & synaptic pruning
  7. Myelogenesis
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2
Q

What are neural stem cells ?

A

Undifferentiated cells that develop into brain & spinal cord

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3
Q

When is neurogenesis largely complete ?

A

Around 4.5 months after conception

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4
Q

In which parts of the brain does neurogenesis continue into adulthood ?

A
  • Olfactory bulb
  • Hippocampus
  • Striatum
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5
Q

From where do stem cells migrate to the developing parts of the brain ?

A

From neural tube/subventricular zone

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6
Q

How do cells ‘know’ where to migrate ?

A

Following road formed by radial cells

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7
Q

How long does migration continue after birth ?

A

Around 8 months

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8
Q

How do layers develop during cell migration ?

A

From the inside out

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9
Q

Into what types do migrated cells differentiate ?

A

Neurons or glia cells

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10
Q

When is cell differentiation essentially complete ?

A

At birth

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11
Q

What are the key processes involved in neural maturation ?

A
  • Dendritic arborization (branching)
  • Growth of dendritic spines
  • Growth of dendrites, axons & synapses
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12
Q

When does neural maturation begin and how long does it continue ?

A
  • Begins prenatally
  • May continue into adulthood
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13
Q

What are the neurobiological processes underlying the critical period of plasticity ?

A
  • Onset : inhibition-excitation balance & deprivation
  • Duration : pruning, rewiring & environmental enrichment
  • Closure : structural brakes, functional brakes epigenetics silence genes rewiring & attentional arousal
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14
Q

What are the key features of neural development in the adolescent brain ?

A
  • Rapid synaptic pruning & growth of connections
  • Especially in PFC
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15
Q

What neural changes occur during adolescence ?

A
  • Differences in GM & WM volume
  • Changes in levels of dopamine & GABA
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16
Q

What are some types of abnormal brain development ?

A
  • Anencephaly
  • Holoprosencephaly
  • Lissencephaly
  • Micropolygria
  • Microencephaly
  • Porencephaly
  • Heterotopia
  • Callosal agenesis
  • Cerebellar agenesis
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17
Q

What’s brain plasticity ?

A

Nervous system’s potential for physical or chemical change that enhances its adaptability to environmental change & its ability to compensate for injury

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18
Q

What are epigenetic changes & can they be inherited ?

A
  • Altered gene methylation & gene expression
  • Can cross to subsequent generations
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19
Q

What internal factors influence brain development ?

A
  • Hormones
  • Injury
  • Nutrients
  • Microbiota
  • Gestational stress
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20
Q

What external factors influence brain development ?

A
  • Environment : exposure to complex vs impoverished environment
  • Experiences : adverse childhood experiences
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21
Q

How does diet and nutrition affect brain development ?

A
  • Gene expression (dry/rainy season)
  • Gut microbiome (& immune function) : brain development, myelination, formation of blood-brain barrier
  • Iron deficiency : anxiety, ADHD…
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22
Q

What are the effects of lead poisoning on brain development ?

A
  • ADHD
  • Autism
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23
Q

How does early visual deprivation affect vision ?

A
  • Long-lasting impairment of vision after optical defects are corrected
  • Amblyopia
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24
Q

How does socioeconomic status (SES) affect brain development ?

A
  • High SES : exposure to more words , more one-on-one conversations, child-directed speech
  • Low SES : associated with lower cortical volumes in frontal, temporal & parietal cortex
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25
Q

How does early auditory experience shape language development ?

A
  • Shape brain’s ability to distinguish sounds of native language
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26
Q

Why does language often survive early left-hemisphere injury ?

A

Appropriation of language zone in R hemisphere

27
Q

What often survives early left-hemisphere injury in the brain ?

A

Language

28
Q

What is a possible consequence of the right hemisphere taking over language functions after early left-hemisphere injury ?

A

Impaired visuospatial orientation

29
Q

What principle explains the greater recovery from brain lesions during infancy compared to adulthood ?

A

Kennard principle

30
Q

How does the developmental stage of injury affect recovery from brain injury ?

A

Recovery depends on developmental stage :
- <1 year : large impairement
- 1-5 years : reorganization of brain function
- >5 years : little or no improvement

31
Q

What factors influence recovery from brain injury ?

A
  • Developmental stage of injury
  • Location & extend of damage
  • Age of assessment
  • Type of behavior affected
  • Sensory experience
  • Hormones
  • Neurotrophic factors
32
Q

To what condition are linked temporal lobe & area TE damage ?

A
  • Temporal lobe : autism
  • Area TE : ADHD
33
Q

What are the mechanisms involved in brain recovery after injury ?

A
  • Changes in the organization of the remaining intact brain circuits
  • Generation of new circuitry
  • Generation of neurons & glia to replace at least some lost neurons
34
Q

What are some examples of neurotrophic factors influencing brain recovery ?

A
  • Tactile stimulation
  • Complex housing
35
Q

What is the incidence rate of neurodevelopmental disorders ?

A

17-25 %

36
Q

What areas can neurodevelopmental disorders affect ?

A
  • Motor behavior (cerebral palsy)
  • General intellectual functioning
  • Learning
  • Attention (ADHD)
  • Social behavior (autism)
  • Communication
37
Q

How are intellectual disabilities diagnosed ?

A
  • Standardized IQ testing
  • Neuropsychological evaluation
  • Assessment of adaptative behaviors
38
Q

Describe the characteristics of mild intellectual disability

A
  • Emerge after during school years
  • Slower development but able to function with minimal support
  • Causes : head injury, stroke, infections
39
Q

Describe the characteristics of moderate intellectual disability

A
  • Major delays in development
  • Able to understand speech & live in a supervised or group home
40
Q

Describe the characteristics of severe intellectual disability

A
  • Limited ability to communicate
  • Physical limitations
  • Need of constant care
  • Causes : prenatal/congenital anomalies
41
Q

What are some examples of intellectual disabilities ?

A
  • Cerebral palsy
  • Hydrocephalus
  • Fragile X syndrome
  • Fetal alcohol spectrum disorder
  • Down syndrome
42
Q

What are the different types of communication disorders ?

A
  • Language disorder
  • Speech sound disorder
  • Childhood-onset speech disorder (sluttering)
  • Social communication disorder
43
Q

What are some specific neurodevelopmental disorders ?

A
  • Reading disabilities
  • Mathematical disabilities
  • Developmental coordination disorder (clumsy child syndrome)
44
Q

What are the symptoms of cerebral palsy ?

A
  • Spasticity (involuntary muscle activity, limbs resist being moved)
  • Athetosis (slow involuntary movements)
  • Rigidity
  • Ataxia (uncoordinated voluntary movements)
  • Impairments in cognitive, emotional functioning (irritability, epilepsy, speech production
45
Q

What causes cerebral palsy ?

A
  • Blood clots
  • Brain trauma during fetal development or birth (up to 5 years postnatal)
  • Infections
  • Traumatic brain injury
  • Prematurity
  • Oxygen depravation at birth
46
Q

What are the underlying neural mechanisms of cerebral palsy ?

A

Lesions of corticospinal tracts, basal ganglia, brainstem, cerebellum

47
Q

What is infant hydrocephalus & what causes it ?

A
  • Hydrocephalus : condition involving accumulation of CSF in brain’s ventricles
  • Causes : malformation, tumor or infection cause blockage of CSF (cerebral aqueduct, intraventricular foramen or 4th ventricle)
48
Q

What are the symptoms of infant hydrocephalus ?

A
  • Severe motor/mental disabilities
  • Dementia
  • Coma/death
49
Q

What are the underlying neural mechanisms of infant hydrocephalus ?

A
  • Damage to the cortex due to expansion
  • Cortex can be stretched but not damaged
50
Q

How is infant hydrocephalus treated ?

A

Draining the ventricles

51
Q

What are the symptoms of fragile X-syndrome ?

A
  • Low ears, high forehead
  • Learning impairement, hyperactivity
  • Boys > Girls
52
Q

What causes fragile X-syndrome ?

A
  • Genetic abnormality of the FMR1 gene
53
Q

What are the treatments for fragile X-syndrome ?

A
  • Glutamate antagonists or GABA agonists
  • Gene replacement/reactivation (under investigation)
54
Q

What are the symptoms of fetal alcohol spectrum disorder ?

A
  • Physical malformations, facial features
  • Intellectual impairements, hyperactivity, social problems
55
Q

What causes fetal alcohol spectrum disorder ?

A
  • Alcohol use (worst during first 3 months of pregnancy)
  • Epigenetic changes in sperm of father due to alcohol use
56
Q

What are the underlying neural mechanisms of fetal alcohol spectrum disorder ?

A
  • General effects on cell division & maturation
  • Epigenetic effects
  • Small brains with abnormal gyri
  • Misaligned cells in the cortex
57
Q

What are the symptoms of autism spectrum disorders ?

A
  • Impoverished social interaction, narrow play
  • Insistence on “sameness” & routines
  • Repeated & stereotypical body movements
  • Inability to cope with new situations & habituate to ongoing events
  • Subts facial anomalies
  • Sometimes exceptional memory or mathematical abilities
58
Q

What causes autism spectrum disorders ?

A

Several theories :
- Highly heritable & epigenetic factors, gene mutations (fragilex)
- Toxins, pollution, microbiome
- Bacterial/virus infections, vitamin deficiency

59
Q

What are the underlying neural mechanisms of autism spectrum disorder ?

A
  • Alterations in glutamate/GABA balance
  • Alterations in somatosensory system, impairment in learning system
  • Differential development of cingulate cortex
  • Central brain stem/pons development
  • Maturation of HOSA1 gene : brain stem & cerebellar development
60
Q

What are the symptoms of ADHD ?

A
  • Impulsivity, hyperactivity : excessive talking, running…
  • Inattention : avoiding tasks, distractability…
  • Creative, flexible & good at task-switching
61
Q

What causes ADHD ?

A

Several theories :
- Brain damage
- Encephalitis (infection)
- Genetic
- Toxins
- Home/school environment

62
Q

What are the underlying neural mechanisms of ADHD ?

A
  • Delayed development of frontal cortex (self-regulation, inhibition)
  • Dysfunction of motivational circuit (reward delay discounting)
  • Reduced orbitofrontal GM
  • Deficiencied of dopamine, noradrenaline & serotonin
  • Dopamine dysregulation in basal ganglia & frontal cortex
63
Q

What are the treatments for ADHD ?

A
  • Methylphenidate & dexamphetamine
  • Cognitive enhancer - stability/flexibility