Nervous System Development Flashcards
Neurulation
Formation of the neural tube
Occurs around 3 weeks
Forms from neural groove
Primary vesicles of the brain
Present at week 3
1. prosencephalon
2. mesencephalon
3. rhombencephalon
Foundational transitions include…
- neural crest -> PNS
- neural tube -> CNS
- central canal -> ventricles in CNS
- autonomic ganglia -> autonomic nervous system
Sulcus limitans
Separates the sensory and motor areas for the posterior/caudal part of the neural tube
Relevant to the spinal cord
Forebrain progresses to…
Telencephalon and diencephalon at 5 weeks
Cerebrum and thalamus, hypothalamus, and epithalamus at birth
Midbrain progresses to…
Mesencephalon at 5 weeks
Midbrain at birth
Hindbrain progresses to…
Metencephalon and myelencephalon at 5 weeks
Pons, cerebellum and medulla oblongata at birth
Choroid plexis
Develops in week 7-15
Makes cerebral spinal fluid
Present on the interior of the brain
Sonic hedgehog (SHH)
Part of the dorsal-ventral patterning
Released from the notochord
Bone morphogenic proteins (BMPs)
Part of the dorsal-ventral patterning
Released from the roof plate
Part of anterior-posterior patterning
Released from posterior side
Controlled by Pax6
Morphogens
Compounds that signal via receptors to control gene expression
Fibroblast growth factors (FGFs)
Part of the anterior-posterior patterning
Released from anterior side
Controlled by EMx2
Netrin
Chemoattractant in the spinal chord
Secreted by the floor plate
Attracts axons to extend to the ventral floorplate and cross to the contralateral side
DCC
Receptor for netrin
Slit
Repellant present on the floorplate of the spinal cord
Axons are insensitive until expression of the Robo receptor (expressed upon crossing the midline)
Robo
Receptor expressed when axons cross the midline of the spinal cord
Causes axon repulsion from slit and netrin
Ephrin A
Chemorepellent responsible for axonal projections from retina to tectum
Engaged in forward signaling and reverse signaling
Ephrin A forward signaling
Ephrin A binds to EphA on growth cone
Leads to repulsion of the axon
Ephrin A reverse signaling
EphA binds Ephrin A expressed on growth cone
Leads to repulsion of the axon
Synaptic pruning
Process that occurs at the end of maturation (after 1st year of life)
Allows for refinement of synapses
Hebb’s rule
Neurons that fire sequentially with strengthen their synapse
Spina Bifida
Neural tube doesn’t close, leaving a gap
Leads to a lack of vertebral formation and herniation in the spinal cord
Location and size of the opening indicates the severity and phenotype
Caused by a folic acid deficiency
Holoproencephaly
Secondary vesicles don’t form properly (failed separation of prosencephalon from diencephalon and telencephalon)
Leads to defects in the formation of longitudinal fissures
Cerebral Palsy
Abnormal development of motor areas (motor cortex, cerebellum)
Caused by lack of oxygen, injury, genetics
Symptoms: lack of muscle coordination, weakness, and tremors
Fetal Alcohol Syndrome
Caused by alcohol consumption during pregnancy
Results in disruption of corpus callosum, hippocampus, caudate, and cerebellum formation
