Ch. 5: Development of Neuroscience Flashcards
Fetal
- 8th week to birth
- Brain formation continues
- Myelination begins
Pre-Embryonic
- conception to 2nd week
- Before organs formed
Embryonic
-2nd week to 8th week
Neural Plate
- Root of all nerve cells
- all nerve cells grow from neural plate
Neural tube
-crests of neural groove grow and connect to form tube
Neural Crest
- part of neural plate that got pinched off when neural tube formed
- differentiates into all somatosensory neurons in body
Neural Groove
-Valley in middle of neural plate
Neuropores
- superior and inferior
- openings at top and bottom of neural tube
Mantle Layer
- inner ring of cell bodies in neural tube
- grey matter
Marginal Layer
- outer ring of axons/glia in neural tube
- white matter
Motor Plate
- (basal, ventral)
- contains motor neurons–ventral horn
- front of mantle layer will connect to myotome
Neural Crest Diversification
- Peripheral sensory neurons
- myelin cells
- autonomic neurons
- endocrine organs
Initial Brain Formation
- Hind brain (medulla, pons, cerebellum)
- Midbrain
- Forebrain (cortical and subcortical structures)
Association Plate
- (alar, dorsal)
- contains interneurons and sensory neurons (dorsal horn)
- dorsal mantle layer (will connect to dermatome)
2 Phases of Nervous System Development
- neural tube formation
2. initial brain formation
Mantle Divisions
- Motor plate (myotome)
- Association Plate (dermatome)
Somite
- develops from mesoderm
- cells on either side of neural tube
- 3 Parts (sclerotome, myotome, dermatome)
Sclerotome
- becomes skull and vertebrae
- anteromedial part of somite
Myotome
- becomes skeletal muscles
- posteromedial part of somite
Dermatome
- becomes dermis
- Lateral part of somite
Migration of Mantle Layer
-Grey matter from inner layer ziplines to outer layer of brain
Neurons Differentiate After:
-migrating to their final location
Growth Cone
-growing axon out toward target
Neural Remodeling
- at first we have way more neurons and connections than we need
- activity shapes connections (increase or decrease strength)
Axon retraction
- the axon loses competition for permanent connection
- pulls axon back (may go elsewhere or dies)
- Synaptic pruning
Fast Motor Neuron
- Goes to fast twitch muscle
- large axon diameter
- highly myelinated
Neuron Connections
- Growth Cone
- NT Release
- Synaptic Connections Formed
Synaptic Connections Formed
-Axons differentiate based on connections they make
Neuronal death
-doesn’t make valid connections and neuron dies
Myelination
- Begin at 4th fetal month
- end around 3 years
Slow Motor Neuron
- goes to slow twitch muscle
- small axon diameter
- less myelination
Anencephaly
- neural tube doesn’t close at top
- only rudimentary brain stem; no cerebellar hemispheres
- skull doesn’t form over incomplete brain
Neural Tube Defects
- Anencephaly
- Arnold-Chiari Malformation
- Spina Bifida
Arnold-Chiari Malformation
- neural tube and foramen magnum get out of alignment
- neural tube slides down and part of cerebellum, medulla and pons are out of foramen magnum and squished against bone.
Cerebral Palsy
- permanent, non-progressive damage to brain before, during or after birth
- movement/posture disorders, cognitive, somatosensory, visual, auditory, speech deficits
- deficits depend when damage occur
- “growing into” deficits common
Spina Bifida
- failure of neural tube to close at bottom
- vertebrae don’t fully or close around the incomplete spinal cord
“Growing Into”
- different rates in different areas of myelination
- peripheral motor (~1 month)
- Central motor (~2 years)
- May not know a disorder is there until kid is older
