Introduction/Basic Physiology

Question 1

What is the helpful pneumonic for thinking through the differential diagnosis of neuropathology?

Answer 1

• VITAMIN C
  
  • Vascular
  • Infectious
  • Traumatic
  • Age-related/degenerative
  • Metabolic/nutritional/toxic
  • Inflammatory
  • Neoplastic
  • congenital

Question 2

What are the 4 foundational cases for understanding the role of the brain and nervous system?

Answer 2

• 1848 - Phineas gage - importance of frontal lobe for behavioral inhibitions
  
  • 1861 - Paul Broca’s patient - stroke in a specific area of the brain causing an inability to form language, combine with other patients and see that that area is the language center
  • 1953 - H.M. - removal of temporal lobe sections bilaterally, or part of hippocampus, and no short term memory, or permanent anterograde amnesia
  • 1999 - transient, reversible depression from Deep Brain Stimulation

Question 3

What are brodmann’s areas?

Answer 3

• Cytoarchitectonic variation in the cerebral cortex
  
  • An accepted way of organizing the architecture of the brain into functional domains
  • 52 total areas now based off of similarities on cellular and tissue level
  • Oversimplified, but still used

Question 4

Where, in relation to the central sulcus, do the primary motor and somatosensory cortices lie?

Answer 4

• Primary motor cortex VENTRAL to central sulcus

* Primary somatosensory cortex DORSAL to central sulcus

Question 5

What are the given examples for behavioral therapies?

Answer 5

• Psychotherapy
  
  • Counseling
  • Biofeedback

Question 6

What are the given examples for physical therapies?

Answer 6

• Surgery
  
  • Exercise
  • Spinal manipulation
  • Electroconvulsive therapy
  • accupuncture

Question 7

What are the given examples for pharmacotherapies?

Answer 7

• Perscription medications
  
  • Non-prescritpion drug use
  • Herbal remedies
  • Diet/nutritional therapies

Question 8

The end goal of therapy for neuropathology is what?

Answer 8

• It all overlaps, produce lasting changes in behavior, lasting functional changes in the circuitry of the nervous system that underlie the behavior

Question 9

What are the given elements of the neurologic exam?

Answer 9

• Mental status exam/psychiatric exam
  
  • Reflex exam
  • Sensory exam
  • Motor exam
  • Cranial nerve exam
  • Examination of coordination and gait

Question 10

What are the given elements for determining neuropathologies?

Answer 10

• The pneumonic - VITAMIN C

Question 11

What are the given elements of the neuroanatomical localization?

Answer 11

• Generalized vs. localized
  
  • Muscle
  • NMJ
  • Peripheral nerve
  • Spinal cord
  • Brainstem
  • Subcortical (Basal ganglia, cerebellum)
  • Cortical (vascular problems?)

Question 12

What are the questions used while determining neuroanatomical localization?

Answer 12

• Can the symptoms be explained by an identifiable pathologic change?
  
  • Can you account for symptoms with a process affecting the NS generally, or can a single focal/multifocal process explain the pattern?
  • If focal can explain symptoms, is it at muscle? NMJ? Peripheral? Spinal cord? Brainstem? Cortical? Subcortical?
  • Does the problem line up with a vascular problem?

Question 13

What is meant by commissure?

Answer 13

In Neurology - A bundle of nerve fibers passing from one side in the brain or spinal cord to the other. - connecting one side of the brain to another as well
* a commissure is neuronal connection between symmetrical sides of the CNS (brain or SC)

Question 14

The fissure of Roland refers to what structure?

Answer 14

• Central sulcus

* Separates the frontal and parietal lobes

Question 15

The Sylvian Fissure refers to what structure?

Answer 15

• Lateral sulcus

* Separates the temporal lobe from the frontal and parietal lobes

Question 16

How many “layers” of the cortex are there?

Answer 16

• 6, and they have to do with cell body layers histologically from superficial (I) to deep (VI)

Question 17

What is meant by somatotopy?

Answer 17

• Topographic association of positional relationships of the body to functional areas of the cerebral cortex

Question 18

What is meant by homunculus?

Answer 18

• The figure of a human, projected with a “scale” to the area of the cortex dedicated to it
  
  • Projected on the brain surface

Question 19

What is a decussation?

Answer 19

• A place in the CNS where fibers from contralateral sides of the brain cross each other
  
  • Depicted in the brain stem
  • Looks like a roman numeral X or 10

Question 20

What important concept did Cajal help define in 1906?

Answer 20

• Neuron doctrine, neurons are the discrete functional units of information processing
  
  • They were surrounded by glia, a more support role cell

Question 21

What important discovery did Kandel elucidate?

Answer 21

• The “epigenetic” component of memory and learning

Neuronal stimulation leads to longer term changes like gene regulation (CREB)

Question 22

What important concept did Hebb postulate in 1949?

Answer 22

• Synaptic plasticity - building and removing connections in the brain
  
  • Neurons that fire together wire together, and thus the cellular basis of learning
  • Hebb’s rule: if cell A fires a lot under a certain stimulus, it’s connections with cell B will grow stronger (more pronounced with neurons firing concurrently)

Question 23

What important concept did Sherrington elucidate in the 1930’s?

Answer 23

• That neurons functioned by electrochemical mechanisms

* Electricity will result in a chemical release which in turn affect electrical current

Question 24

What direction is the information flowing in the dendrite? The axon?

Answer 24

• From dentrite to soma, from soma through axon

* Dentrite is afferent, axon is efferent

Question 25

How many ventricles in the brain?

Answer 25

* 4, two lateral and then III and IV * The lateral ventricles feed into the midline III ventricle which goes into the IV ventricle, the farthest back in the neural tube * Lateral ventricles are in the cerebral cortex * The C shape of the lateral ventricles is a big clue to the folding of the neural tube * The forebrain portion of the neural tube bends down and "under" to make the C shape

Question 26

What does CSF look like and where is it produced?

Answer 26

* CSF is normally clear, made by choroid plexus, a specialized structure within the ventricles * Specialized secretory tissue sitting within lateral ventricles * Ventricles hold about 10mL of fluid * From the IV ventricle CSF goes into the subarachnoid space, surrounding the entire CNS * You make way more CSF than the whole system can hold * There are apertures in the IV ventricle that allows for CSF to get into the rest of the system, and if there is any block, there is a buildup of fluid because choroid plexus doesn't change the production * The result is hydrocephaly, and the ventricles expand into the neighboring tissues, eventually causing damage to neuronal tissue

Question 27

What vessels supply blood to the anterior surface of brain vs. posterior portions?

Answer 27

* Posterior = from vertebral artery * Anterior = from internal carotid * Very little overlap between the two systems normally * But very few brains are normal. There are often variations in the patterns of cerebral arterial architecture

Question 28

What is the cellular basis for fMRI?

Answer 28

* Synaptic activity results in local increases in blood flow * Due to coupling of glial responses with vessel dilation * Astrocytes monitor synaptic activity via metabotropic glutamate and ATP receptors * Increases in extracellular ATP or glutamate (consistent with lots of NT release) will increase intracellular Calcium through IP3 signalling * Astrocytes respond to increased calcium through releasing metabolites of the COX-1 pathway * Result is smooth muscle relax and vessel dilation * Can be blocked by COX inhibition

Question 29

What are the white matter terms vs. grey matter terms?

Answer 29

• Ie. Peduncles, tracts, nucleus, etc.

Question 30

Do neurons have direct access to capillaries?

Answer 30

* NOPE. They are surrounded by glial cells * Thus a CNS drug MUST be highly lipophilic and have a high volume of distribution * The glial cells and the endothelial cells in BBB are densely packed with selective, active transport mechanisms

Question 31

How do astrocytes deal with the circulatory system?

Answer 31

* They help establish and maintain the BBB * Astrocytes surround cerebral blood vessels to regulate blood flow and keep crap from leaking out * Astrocytes maintain endothelial cell tight junctions * Endothelial transplant cells will, when astrocytes are present, go from being fenestrated to having tight junctions, showing astrocytes are responsible for that signaling pathway

Question 32

In PNS, what glial response helps regenerate an axon?

Answer 32

* Need to get better info on this * Microglia are activated, schwann cells help re-establish connections * In CNS, the astrocytes inhibit axonal re-growth

Question 33

What happens to the saturating neurotransmitter in the synapse?

Answer 33

* That's one of the functions of the astrocytes. They suck up the extra neurotransmitter with high affinity receptors * Either recycle it back to the axon terminals or it enymatically destroys it * The neuron terminals themselves have limited re-uptake? * Astrocytes can modulate the activity of the synapse, and in part because of this re-uptake mechanism/job

Question 34

Is it the transmitter that determines the valence of a synapse?

Answer 34

* Valence is inhibitory/excitatory. | * NO, the transmitter is received by a receptor that dictates the response

Question 35

Do microglia only react to local damage?

Answer 35

* No. evidence from mice suggest that microglia will be activated at the brain-termini even from a nerve that has been cut in the periphery * They are ripping out now-useless terminals from damaged nerves. Don't waste brain space * Play a role in the plasticity of the brain

Question 36

Do microglia come from the same embryonic place as the rest of the nervous system?

Answer 36

• Nope. They do not come from ectoderm • Think of them as the macrophages of the brain and they arise accordingly from hematopoietic areas • Migrate into brain before BBB forms If there is a high concentration of ATP in a tissue, what is that indicative? • Tissue damage/injury • Think of the microglia movie where they attacked the ATP leak in the brain

Question 37

Schwann cells do what?

Answer 37

* Determine axonal regeneration * In the PNS, not the CNS * Produce myelin

Question 38

Oligodendrocyte does what?

Answer 38

* Wraps axons with myelin * Also called oligodendroglia * Lays on top of the axon and wraps it with lipid rich myelin * They live within the CNS. Not PNS. Marks the change * Essentially form a barrier to axonal regeneration. Thus injury in CNS stays as such

Question 39

What is chromatolysis?

Answer 39

• Loss of coloring by histologic stain due to the negative feedback loop, think of a motor unit no longer needed because of injury or something

Question 40

What is retrograde signal?

Answer 40

* Feedback mechanisms from axon terminal that determines continued sending of proteins along cytoskelaton or not * Like a muscle that is now injured, that neuron innervating the motor unit will have feedback to stop spending so much energy on it

Question 41

Glial cells in the PNS permit what?

Answer 41

* Regeneration, which doesn't happen in CNS? | * Yes, there is a glial "barrier" to regeneration in the CNS

Question 42

Glial cells in the PNS permit what?

Answer 42

* Regeneration, which doesn't happen in CNS? | * Yes, there is a glial "barrier" to regeneration in the CNS

Question 43

What are the three main types of glial cells?

Answer 43

• Myelinating glia, microglia, astrocytes

Question 44

What is axoplasmic flow?

Answer 44

* Transported proteins from soma to periphery * Protein synthesis is NOT in the axon mostly (very few ribosomes in the axons or dendrites) * When axons are separated, the peripheral end degenerates while the proximal end, attached to soma, is fine * Another reason why neuronal regeneration can get a bit weird. Axons grow where they may and the plasticity of the brain re-interprets the new informational architecture

Question 45

What are Nissl bodies?

Answer 45

* The tons of densely packed ribosomes on the RER | * Neurons make a ton of proteins (big cell, long processes, and tons of cellular transport)

Question 46

What is a Nissl stain and what does it do?

Answer 46

* Very common neurological histology stain, preferentially stains RNA, helpful for seeing nucleolus of soma * The nucleus of the soma by comparison are quite clear

Question 47

What is the axon hillock?

Answer 47

* Specialized (electrically) area as soon as the axon comes off the soma * Determines whether an action potential will be propagated

Question 48

What property of water molecules can be harness for a fMRI?

Answer 48

• The fact that water molecules tend to move "down" the tract of axons so you can "map" the direciton of water molecules and thus tracts through the brain