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X-linked filamin defect
- Filamin A is an actin-binding protein important for initiation of migration
- X-LINKED
- Males - Die in eutero
- Heterozygous females - Late onset seisure and some mild retardation
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Doublecortin (DCX) defect
- Doublecortin (DC X-linked) is a microtubule- associated protein important for staying on the migration path migration.
- X-LINKED
- Males - X-linked lissencephaly (“smooth brain” with no gyri) or pachygyria (fewer than normal gyri) and severe retardation
- Heterozygous Females - double cortex (subcortical laminar band heterotopia, SBH)
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Miller-Dieker Syndrome
- LIS1 gene defect (on chromosome 17) codes for a microtubule-associated protein important for maintaining the proper speed of migration
- AUTOSOMAL
- Autosomal - severe mental retardation- thickened cortex and paucity of gyri and sulci
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Reelin Defect
- Reelin is an extracellular matrix protein important for termination of migration Cajal-Retzius cells, secrete Reelin, which accumulates just below the pial surface.
- AUTOSOMAL
- Early born neurons won't get off the track blocking later more cortical neurons. Createing Inverted corical lamination and lissencephally
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Cortical Development
- Ventricular zone to cortex
- Climbing up strands of radial glial cells
- Ependymal (neuro stem cells) to Pia surface (differentiated neurons)
- Stages
- 1. Neurogenesis
- 2. Migration
- 3. Arborization (extension of dendrites and axons)
- 4. Myelination (of axons) 5. Synapse formation and elimination
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6 layed neo cortex
- 1. Molecular layer
- 2/3. Supragranular layer -Pyrimidal (glutametergic corticocortical connection only but both associational and commisural)
- 4.Granular (mostly in primary sesory areas, not in primary motor)
- 5. Infragranular - Large pyrimidal and amorphic (both corticocortical and cortifugal)
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Nerve regeneration
- CNS cannot
- PNS only with help of Schwann cells providing guidence
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MRI Weights
- T1 weighted = grey looks grey and white matter looks white
- T2 weighted = Grey looks white and white matter looks dark
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Subdural hematoma
- Crescent shaped - maintains the countured shape of brain
- Opens up potential space between Dura mattar and arachnoid matter
- vein at attachment to sinuses
- Dural venous sinus
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Epidura hematoma
- Football shapped hematoma - indents into the brain rather than countours it
- Above dura
- Meningeal Artery
- Dura venous sinous
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Tentorial (Uncle) Herniation
- Uncus of medial temporal lobe herniates through the tentorial notch. Into the cerebellum space.
- Extra stuff presses on the midbrain against the other edge of the tentorial notch
- Cerebral peduncle deficient
- PCA (occipital lobe hypoperfusion)
- CN III gaze palsy
- Coma
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Tonsilar Herniation
- Cerebellum herniation through foramen magnum
- Cerebellar mass causing one tonsil to herniate and pressing on the brain stem below (medulla compression)
- Rapidly fatal as Medulla contains cardio and respiratory centers.
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Facial Colliculus
- at level of mid pons and cuts through facial nucleus and abducens nucleus
- Facial colliculus is produced as facial nerves wrap around the abducent nerve producing a bulg in the 4th ventricle

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Abducens nerve
- Innervates lateral rectus muscle
- comes out at the front of the ponto medulla junction just medial to the facial nerve
- This is the most medial nerve at the pons/medulla junction and easily damaged due to long intracranial course
- Functions in vestibulo-occula and conjugate gaze reflexes--> yolks CNIII to adduct towards side of head turning through the Medial Longitudenal Fasiculus
- Recieves information paramedian pontine reticular formation (which recieves info from cortex, vestibular nuclei and superior colliculus)
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Olfactory Nerve
- Primary olfactory --> glomeruli via Mitral Cells
- Glomeruli --> olfactory track
- taste receptor--> 1st order sensory neuron--> solatary nucleus (2nd order neuron)--> VPM (3rd order)--> insula and frontal cortex
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Anterior commissure
- Just below the fornix a strip of white matter that mirrors the function of the corpus colusom but much smaller
- connects the temporal lobes, the amagdala, and recieves info from olfactory
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Taste Nerves
- receptors --> CN VII, CN IX, CN X--> solitary nucleus --> VPM--> insula
- Or solitary nucleus --> hypothalamus/Amygdala
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Filiform Papillae
- all over tongue, no taste buds, like sand paper
- karetinized epithelium
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Fungiform Papillae
- All over anterior part of tongue
- Taste nerve
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Circumvallate (vallate) Papillea
- Posterior part of the tongue
- Large circles at the base of the tongue for taste
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Folate Papillae
- on the side of the tongue
- Rudimentary
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Sleep stages
- Awake --> alpha/beta waves
- N1 (drowsiness)--> theta wave--> hypnic jerk and hypnagogic hallucinations
- N2 (light sleep)--> sleep spindles and K complexes --> decreased muscular activity and accounts for 45-55% of sleep
- N3(deep slow wave sleep) --> delta waves --> night terrors, bed wetting, sleep walking and talking
- REM --> beta waves --> rapid eye movement and low voltage EEG, muscular atonia( complex relaxation) and vivid dreams 20-25% in adults
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Suprachiasmatic nucleus
- Part of the hypothalamus that works with pineal gland to regulat circadian rythem
- Takes information from retina and raphe nuclei
- Efferent to pineal gland
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Raphe Nuclei (sleep)
- Reticular nuclei at multiple locations that secret seratonin
- in respect to sleep it fires before and after REM to terminate the episode
- Normally present during awake
-
REM terminators
- Serotonin --> raphe nuclei
- Norepi --> Locus ceruleus
- Orexin --> lateral hypothalamus (dorsal medial nucleus)
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Narcolepsy
- Can be caused by the absence of orexin
- Intrusion of REM sleep during periods of wakefullness
- sleepy during the day
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REM initiator
GABA --> preoptic area
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Pineal gland activation route
Retina (light)--> suprachiasmatic nucleus (hypothalamus) --> reticular formation in ventrolateral medula--> intermediolateral neurons of spinal chord--> superior cervical ganglion (sympathetic control) --> pineal gland
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Paraventricular and supraoptic nuclei
- Neurohypothesis
- Release ADH and oxytocin
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Arcuate nucleus
- DOPA-nergic neurons controls prolactin relase from antierior pituitary
- GHRH and possibbly other pituitary control hypothalimus releasing hormones
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Preoptic
- Sleep initiation with GABA secretion
- sexual dimorphic nucleus--> GnRH secretion
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Suprachiasmatic
- Sleep cycle and circadian rythm
- Pineal gland activation
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