Lecture 22

Question 1

__ neurons in the sleep cycle

Answer 1

thalamocortical

Question 2

the control of sleep and wakefulness depends on the __ modulation of the __ and the __

Answer 2

brainstem; thalamus and cortex

Question 3

hypothalamus provides modulatory input to the __, which then acts on the __ (__ connections)

Answer 3

brainstem; thalamus; cortex

Question 4

thalamocortical neurons exist in two states

Answer 4

asleep (bursting/oscillatory) and awake (tonically active)

Question 5

the tonically active state occurs when the thalamocortical neurons are __

Answer 5

depolarized

Question 6

tonically active state: information is transmitted to the cortex in a __ fashion - __

Answer 6

asynchronous; encoding peripheral stimuli

Question 7

bursting/oscillatory state: activity between __ and __ becomes __ (as in the sleep state)

Answer 7

thalamus and cortex; synchronous

Question 8

modulation of the thalamocortical loops generates eeg __

Answer 8

signatures of sleep

Question 9

henry head experiment

Answer 9

he cut his own radial nerve to determine the extent of the regenerative capabilities of the PNS, and the area of insensitivity decreases (regeneration)

Question 10

henry head results

Answer 10

after 6-13 weeks, return of general sensitivity (protophathic abilities); epicritic abilities (fine motor, pin prick, 2 point dicsrimination, light touch) returned more slowly (>2 years

Question 11

what do the henry head results suggest?

Answer 11

a difference in recuperative abilities of different dorsal root ganglion and spinal motor neurons (some recovered quickly, some did not)

Question 12

acute axonal degeneration: (3)

Answer 12

axonal skeleton disintegrates, axonal membrane breaks apart (blebbing/swelling), myelin sheath breaks apart

Question 13

acute axonal degeneration occurs rapidly (axons breaks apart in a day, sheath is degraded within 2-3 days) in __, and slowly (axons take days, myelin sheath takes months) in __

Answer 13

the PNS; the CNS

Question 14

acute axonal degeneration is caused by local increases in __ that occur __, and activate __ which begin axon fragmentation

Answer 14

Ca; after injury; proteases (Calpain)

Question 15

severing the axon prevents __

Answer 15

trafficking

Question 16

in an injured axon, __ can no longer make it to the __ portion of the axon. and axon can no longer maintain appropriate levels of __ so __ get overwhelmed and ER releases __

Answer 16

NMNAT2; distal; Ca; mitochondria; internal Ca stores

Question 17

Ca activates __ pathways

Answer 17

death

Question 18

repair and regenration: in the PNS, schwann cells __ (2), and macrophages are __ cells that __

Answer 18

do the initial clean-up and recruit macrophages; immune; take several days to clean up the debris

Question 19

both schwann cells and macrophages secrete molecules essential for __

Answer 19

successful regeneration

Question 20

schwann cells secrete signaling molecules (__ 3) into the __ to guide regeneration

Answer 20

laminin, fibronectin, collagens; extracellular matrix

Question 21

regenerating axons express __ which mediate recognition of the matrix and mediate __ and facilitate __

Answer 21

integrins; intracellular signaling; growth

Question 22

integrins are a family of receptor molecules found on __ that bind to __ such as laminin

Answer 22

growth cones; cell adhesion molecules

Question 23

integrins work alongside other receptors such as cadherins, which are a family of __ found on the surface of __

Answer 23

calcium-dependent cell adhesion molecules; growth cones or cells over which they grow

Question 24

the extracellular matrix, defined by the __, provides a conduit for the regenerating axon

Answer 24

schwann cell processes

Question 25

Wallerian degeneration

Answer 25

macrophages eating myelin sheath slowly

Question 26

in response to schwann cell actions, regenerating peripheral neurons change __ and __ to accommodate regrowth

Answer 26

gene expression; protein trafficking

Question 27

in response to schwann cell actions, __ and __ change back to growth state

Answer 27

actin and microtubule cytoskeleton

Question 28

regenerative properties of schwann cells are so strong they can be used to repair the __

Answer 28

CNS

Question 29

axons from a crushed optic nerve can travel through a __ to reach targets in the brain

Answer 29

peripheral nerve graft

Question 30

axon guidance is mediated by __ and __

Answer 30

chemoattraction and chemorepulsion

Question 31

__ guide the growing axon and rely on __ (molecular cues) to direct the growing axons to the right direction

Answer 31

growth cones; axon guidance molecules

Question 32

growth cones are dependent on __

Answer 32

receptors and concentration gradients of molecular cues

Question 33

after denervation, original NMJ synpatic sites __

Answer 33

remain (in the absence of the synapse itself) for weeks

Question 34

synaptic sites and nearby schwann cells secrete __ (__ 2) near the site of the __

Answer 34

guidance cues (neurotropins (NGF, etc.) and target adhesion molecules); denervated motor end plate

Question 35

__ (2) signaling is necessary to recapitulate target recognitions and synaptogenesis

Answer 35

tropic and trophic

Question 36

there is imprecision in re-innervation: __ (much of which is eventually eliminated)

Answer 36

polyneuronal innervation

Question 37

activity-dependent processes: __

Answer 37

polyneuronal innervation

Question 38

also need activity-dependent refinement to eliminate __

Answer 38

aberrant synapses

Question 39

once synaptic connections are established, neurons become dependent on their targets for their __ (2) = __

Answer 39

survival; continued growth and differentiation; trophic interaction

Question 40

trophic interaction is controlled by __ = molecules provided by target cells that regulate __ and __ of nearby cells

Answer 40

neurotrophic factors; growth differentiation and survival

Question 41

if there is a surplus of neurons born, __

Answer 41

fewer make connections

Question 42

neurons that fail to __ are eliminated

Answer 42

connect with appropriate targets

Question 43

NGF is an important

Answer 43

neurotropin

Question 44

the ability for the brain to repair itself is __, the damaged brain does not produce __

Answer 44

limited; large numbers of new neurons

Question 45

3 barriers to CNS repair

Answer 45

neuronal death, glia cells actively inhibit axon growth, few neural stem cells with limited abilities for growth and differentiation

Question 46

glial cells actively __ in the CNS

Answer 46

inhibit axon regeneration

Question 47

brain injury causes __ of glial precursors

Answer 47

local proliferation

Question 48

glial scar is when __

Answer 48

glia infiltrate the site of injury and persist

Question 49

regeneration is blocked for 3 reasons

Answer 49

glia scar is a physical barrier, astrocytes and oligodendrocytes secrete molecules that inhibit axon growth, and ECM lacks developmental adhesion molecules

Question 50

molecules that inhibit axon growth (secreted by astrocytes or oligos)

Answer 50

epherins, semphorins, slit, and NogoA

Question 51

in the adult brain, neurogenesis occurs __

Answer 51

in select areas

Question 52

2 areas with high levels of neurogenesis in adult brain

Answer 52

olfactory bulb and hippocampus

Question 53

new nerve cells are primarily __

Answer 53

interneurons

Question 54

progeny of neuronal stem cells - close to the surface of the __

Answer 54

lateral ventricle (subventricular zone)

Question 55

most new nerve cells __

Answer 55

die before they are integrated