30 - Cortex

Question 1

Neurulation Defects

Answer 1

• Anencephaly: failure of anterior neuropore to close
• Rachischisis: failure of posterior neuropore to close
• Spina Bifida: incomplete formation of vertebrae and meninges
  
  • Occulta: vertebrae defect
  • Meningocele: meninges live under skin
  • Meningomyelocele: meninges and SC live under skin

Question 2

Heterotopia

Answer 2

• Gray matter malformation of cortical development
• During migration (stage 5)
• Clusters of neurons have stalled along their migration route (haven’t migrated from the ventricle to the cortex, hence why they appear in the ventricle ->)
• Depending on how extensive they are, neurologic and developmental effects may be severe or isolated (e.g., focal seizures with normal psychomotor development)

Question 3

Fetal Alcohol Syndrome

Answer 3

• Many developmental defects including microencephalopathy (abnormally small brain) due to alcohol-induced interference with neuronal proliferation or alcohol-induced death of vulnerable neurons in the early stages of differentiation
• Children often have impaired learning, hyperactivity, and seizure disorders

Question 4

Cocaine Abuse during Pregnancy

Answer 4

• Drug can cross the placenta and interact with receptors on fetal neurons
• Cocaine impairs synaptic re-uptake of monoamine NTs epinephrine, norepinephrine, and DA
• Because monoamines influence the development of neuronal circuits, exposure to cocaine during fetal life can permanently alter the physiological and structure of developing neurons
• Individuals exposed to cocaine in utero often have neurological, cognitive, and behavioral dysfunction throughout their lives
• Cocaine can also induce vasospasm, leading to ischemic stroke

Question 5

Multiple Sclerosis

Answer 5

• Autoimmune disease in which CNS lesions result from perivascular immune cell infiltration associated with damage to myelin, oligodendrocytes, and neurons.
• May arise from interaction between genetic and environmental factors
• Signs/symptoms vary widely depending on the functional neuroanatomy of the regions affected
• Three main characteristics:
  
  • Formation of lesions (plaques) in CNS
  • Inflammation
  • Destruction of myelin sheaths of neurons
• Why may there be cognitive impairments and mood disorders?
  
  • Neuromodulators need myelination to reach further neurons
    
    • Ex: disruption of cholinergic axonal projections originating from the NBM may affect attention systems, behavior, etc.

Question 6

Pyramidal Cell Layers, Components, and Connections

Answer 6

• Predominant in levels III and V
• Components
  
  • Large apical dendrite that arises from apex of cell body and extends towards the molecular layer
  • Basal dendrites run in horizontal direction
  • Abundant dendritic spines receive majority of contacts
  • Single axon originates from the base of soma, leaves the cortex and passes deeply into white matter
• Connections
  
  • Cortico-cortical
  • Cortico-fugal

Question 7

Granule Cell Layers

Answer 7

Layer II and IV

Question 8

Staining Techniques

Answer 8

• Golgi stain: lights up entire cell, paradoxically about 1 in every 100 cells
• Nissl stain (RNA)
• Weigert stain: elastin glycoprotein stain

Question 9

Bands of Baillarger

Answer 9

• Horizontal myelinated fibers in layers IV and V, readily visible on Weigert stains

Question 10

Stria of Gennari

Answer 10

• Enlarged outer band of layer IV in the primary visual cortex

Question 11

Agranular vs Granular

Answer 11

• Agranular: thick pyramidal layers (limbic, motor cortex)
• Granular: thin pyramidal layers (sensory)

Question 12

Short Association Fibers

Answer 12

Originate in layer II

Question 13

Long Association FIbers

Answer 13

Originate in layer III

Question 14

Callosal/Commissure Fibers

Answer 14

• Originate in layer III
• Have Von Economo spindle neurons
  
  • Originate in layer
  • Comprise the claustrum
    
    • Important for consciouness, duration of coma

Question 15

Superior longitudinal fasciculus

Answer 15

connects frontal to occipital lobe, as well as points between (parietal)

Question 16

Arcuate fasciculus

Answer 16

connects Wernicke’s and Broca’s (language)

Question 17

Inferior longitudinal fasciculus

Answer 17

temporal pole to occipital pole

Question 18

Cingulum

Answer 18

interconnecting neurons within cingulate gyrus

Question 19

Inferior fronto-occipital fasciculus

Answer 19

frontal lobe to occipital lobe inferiorly

Question 20

Uncinate fasciculus

Answer 20

prefrontal cortex to temporal pole (hook shape)

Question 21

Lateralization of FUnction

Answer 21

• LEFT
  
  • Language
  • Emotions from verbal stim
  • Spatial functioning of OBJECTS
• RIGHT
  
  • Non-verbal language
  • EMotions from nonverbal
  • Spatial functioning HOLISTIC