Neurodevelopment Flashcards
1
Q
What week does the neural plate begin to form
A
3rd
2
Q
How does the neural plate form
A
Ectoderm thickens in the mid-line
3
Q
How does the neural groove form
A
Neural plate undergoes differential mitosis to form the neural groove
4
Q
How does the neural tube
A
The neural groove deepens and eventually detaches from the overlying ectoderm to form the neural tube
5
Q
Where do the neural crest cells lie
A
Lateral to the neural plate
Run dorsolaterally along the neural groove
6
Q
What do neural crest cells form
A
Sensory ganglia, Schwann cells, adrenal medulla, meninges and dermis
7
Q
Which week does the prosencephalon, mesencephalon and rhombencephalon develop
A
By week 5
8
Q
What has happened by week 5
A
The prosencephalon, mesencephalon and rhombencephalon have developed
9
Q
By what week have the secondary brain vesicles developed
A
7
10
Q
What do the secondary brain vesicles give rise to
A
The mature brain
11
Q
Timeline of brain development
A
Week 3- ectoderm —>neural plate —> neural groove —> neural tube
Week 5- prosencephalon, mesencephalon and rhombencephalon develop
Week 7- secondary brain vesicles develop
12
Q
Primary brain vesicles
A
prosencephalon, mesencephalon and rhombencephalon
13
Q
Secondary brain vesicles
A
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
14
Q
What are the secondary brain vesicles of the prosencephalon
A
Telencephalon
Diencephalon
15
Q
What secondary vesicles are part of the rhombencephalon
A
Metencephalon
Myelencephalon
16
Q
Derivative in mature brain of prosencephalon
A
Cerebral hemispheres
Lateral ventricles
Thalamus
Hypothalamus
3rd ventricle
17
Q
Derivative in mature brain of mesencephalon
A
Midbrain
Aqueduct
18
Q
Derivative in mature brain of rhombencephalon
A
Cerebellum
Pons
Upper 4th ventricle
Medulla oblongata
19
Q
What week does eye formation begin
A
3
20
Q
Developmental milestones: cerebral expansion and commissures
A
10 weeks
21
Q
Developmental milestones: basic structures
A
3 months
22
Q
Developmental milestones: eye formation
A
3 weeks
23
Q
Developmental milestones: myelination has begun
A
5 months
24
Q
Developmental milestones: lobes and cerebrum have formed
A
7 months
25
Developmental milestones: gyri and sulci have formed
9 months
26
What are CNS abnormalities dependent on
Time of infection
27
Week 6 infection causes
Eye malformations
28
Week 9 infections cause
Deafness
29
Week 5-10 infections cause
Cardiac malformation
30
When do CNS abnormalities typically occur
2nd trimester
31
When does the risk of CNS disorders fall
After 16 weeks as most structures have developed by this point
32
When is the dermal skin innervated
28 weeks
33
When do the dorsal root ganglia connect to the spinal cord
8 week
34
Non-noxious development of sensation
Dorsal root connect to the spinal cord from 8 weeks
35
When does C-fibre connection occur
19 weeks
36
Noxious development of sensation
C-fibre connection occurring in week 19
37
When does the organised thalamus occur
Week 8
38
When does retinal input arrive
14-16 weeks
39
When does myelination occur
Week 25
40
When does the connection from the thalamus to the cortex occur
24 weeks
41
Eye malformation
Week 6 infection
42
Deafness
Week 9 infections
43
Cardiac malformations
Weeks 5-10 infections
44
Development of sensation timeline
Week 8: dorsal root ganglia connect to spinal cord (non-noxious) and organised thalamus
Week 14-16: retinal inputs arrive
Week 19: C-fibre connection occurs (noxious)
Week 24: connection from the thalamus to the cortex
Week 25: myelination occurs
Week 28: dermal skin is innervated
45
When does the blood-brain barrier begin to form
Week 8
46
What is the blood-brain barrier formed by
Endothelial cells
Pericytes
Astrocytes
(Endothelial tight junctions and continuous basement membrane)
47
Which parts of the brain lack a blood-brain barrier
Circumventricular organs
I.e. posterior pituitary needs to be connect with blood as has a sensory role
48
At what week should the neural tube be closed
Week 4
49
Spina bifida
Failure of the closing of the spinal cord by week 4
50
Anencephalus
Failure of the neural tube closing in the Cephalic region
51
Detection of brain activity
Increased neural activity results in increased release of neurotransmitters and their breakdown products
More neurally active regions require more oxygen and blood
52
EEG (electroencephalogram)
Indication of regional brain activity
electroencephalogram (EEG) is a test that measures electrical activity in the brain using small, metal discs (electrodes) attached to the scalp
Useful for detecting signs of epilepsy
Over-excitation of neurons can lead to cell death
53
Modern imaging techniques monitor haemodynamuc changes
More neurally active regions require more oxygen and blood
54
CSF lumbar puncture
Increased neural activity results in increased release of neurotransmitters and their break down products
55
Ways to detect brain activity
Lumbar puncture
Monitoring haemodynamic changes
EEG (electroencephalogram)
56
What percentage of the brain is fat
60%
57
At what age are you ambidextrous until
3 years
58
Primitive reflexes
Rooting Reflex: turn head and mouth in direction of stroking of cheek
Sucking Reflex: babies will suck object that touches the lips
Moro (Startle) Reflex: back arches, legs and arms are flung out and then brought back toward chest into a hugging motion
Grasping (Palmar) Reflex: babies grasp objects pressed against palms
Stepping Reflex: babies will mimic walking when help upright
Babinski Reflex: infant fans toes when feet are stroked
Tonic-Neck Reflex: infant turns head to one side, extending arm and leg
59
How far away are objects from the eyes when seen best
7-9 inches
60
Vision when born
Lack peripheral vision
Able to track movement within 1 day of birth
Convergence does not occur until 7/8 weeks
Cones less developed than rods at birth, but at 3 months can see most visible colours
61
Hearing when born
Middle and inner ear mature in shape and size. So hear remarkably well
Show preference for mothers’ voice
62
Smell at birth
Smell well developed at birth
Demonstrate facial expressions to different odours
Aversion for noxious and preference for pleasant odours
Recognize familiar odours
Learned preference for mother
63
Taste at birth
Tastes sensitive at birth
Discriminate between salty, sour, and bitter tastes
Prefers sweet – works as an analgesic
64
Developmental progress
Cranial to caudal
Proximal to distal
Simple to complex
65
Left hemisphere responsible for
Verbal, Speaking, Reading, Thinking, Reasoning, Processes information sequentially, One piece of information at a time
66
Right hemisphere responsible for
Nonverbal, Spatial relationships, Patterns/Drawing recognition, Music, Emotional expression, Processes information holistically
67
Red flags of development
Syndromic children/Dysmorphisms
History of brain injury
Any loss of skills at any age
Visually not fixing or following an object
Hearing loss
Low or High muscle tone
Squint after 3 to 4 months (6th nerve)
Cannot hold object placed in hand at 5 months
Can’t sit unsupported by 12 months
Boys not walking by 18 months
Girls not walking by 2 years
Persistent toe walking
No speech by 18 months
Can’t point at object to share interest with others by 2 years
Handedness before 3 years old
68
Folic acid (B9) supplementation
Reduces the risk of spina bifida and anancephaly
69
Lissencephaly disorder
Smooth brain
Neuronal migration
Unreactive neonate
70
Fetal alcohol syndrome
No safe level
Bingeing is worse but as little as 2 units per day can affect a fetus
Low nasal bridge, short nose and flat midface, small forehead (microcephaly), thin upper lip
71
Cystic periventricular leukomalacia
Death of oligodendrocytes
Around 5% of babies less than 32 weeks
72
When does eye convergence occur
7/8 weeks
73
By what age can babies see most visible colours
3 months
74
Ventricular haemorrhage
Around 80% of babies less than
32 weeks have a normal scan
Around 14% have small bleeds
Around 6% of babies less than
32 weeks have scans like these
Neonatal brains display significant plasticity
75
What layer of the primitive streak forms the nervous system
Ectoderm
76
The ectoderm forms
Skin
Nervous sustem
77
The endoderm forms
Epithelial lining of gut and respiratory system
Liver
Oancreas
78
The mesoderm forms
Notochord
Muscular system
79
When does Gastrulation occur
Week 3
80
Formation of spinal cord
Ectoderm thickens in midline to form the neural plate
81
Formation of neural tube
1. Notochord forms the mesoderm cells soon after Gastrulation is complete
2. Signals from notochord cause inward folding of ectoderm at the neural plate
3. Ends of the neural plate fuse and disconnect to form an autonomous neural tube
82
Where do the presumptive neural crest cells lie
Lateral to the neural groove
83
What do the spinal ganglion give rise to
Dorsal root ganglio
84
Where do the spinal ganglion lie
Either side of the neural tube
85
What do the neural crest cells give rise to
Schwann cells
Adrenal medulla
Bony skull
Meninges
Sensory dorsal root ganglia of spinal cord and V/VII/IX/X
86
What do the mesoderm give rise to
Osteoblasts
Osteoclasts
Adipocytes
Chondrocytes
87
What do the ectoderm cells give rise to
Melanocytes
Schwann cells
Neurons
88
When does the neural tube close
End of 4th week
89
Anencephaly
Failure to close Cephalic region of neural tube
90
Spina bifida
Failure to close spinal region of neural tube
91
Environmental factors of spina bifida
Folic acid
Maternal diabetes
92
Brain development - week 4
Prosencephalon – cerebral hemispheres and thalamic structures
Mesencephalon – midbrain
Rhombencephalon – medulla, pons and cerebellum
93
Microcephaly
Reduced head circumference
94
Macrocephaly
Increased head circumference
95
Periventricular nodular heterotopia
Abnormal migration of neurons
96
Meningocele
Protrusion of the meninges
97
Myelomeningocele
Protrusion and opened spinal cord
98
Hydrocephalus
Accumulation of CSF with increased intracranial pressure
Can cause macrocephaly in children (therefore always scan increasing head size)
Obstructive (non-communicating): e.g. tumour, haemorrhage.
Non-obstructive (communicating): e.g. increased CSF production
99
When are most spinal cord defects detected
20 week scan
100
Brain development- week 6
Telencephalon
Diencephalon
Mesencephalon
Rhombencephalon
Fourth ventricle
Brainstem
101
What does the prosencephalon give rise to
Cerebral hemispheres
Thalamic structures
102
What does the mesencephalon give rise to
Midbrain
103
What does the rhombencephalon give rise to
Medulla
Pons
Cerebellum
104
Is microcephaly or macrocephaly more likely to be indicative of pathology
Microcephaly- stem cells have not divided properly (eg teratogens )
For example alcohol fetal syndrome
105
Neural crest cells don’t form…
Astrocytes
106
Developmental milestones: week 3
Eye formation
107
Developmental milestones: week 10
Cerebral expansion and commissures
108
Developmental milestones: 3 months
Basic structures
109
Developmental milestones: 5 months
Myelination has begun
110
Developmental milestones: 7 months
Lobes and cerebrum have formed
111
Developmental milestones: 9 months
Gyri and sulci have formed
112
The nervous system begins to form in week 3 after fertilisation.Which of the following statements about the embryology of the spinal cord is true- formed from?
Ectoderm
113
Which embryological structure is the precursor to the developing pons and cerebellum?
Metencephalon
