Lecture 22 Flashcards Preview

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Flashcards in Lecture 22 Deck (55):
1

__ neurons in the sleep cycle

thalamocortical

2

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

brainstem; thalamus and cortex

3

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

brainstem; thalamus; cortex

4

thalamocortical neurons exist in two states

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

5

the tonically active state occurs when the thalamocortical neurons are __

depolarized

6

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

asynchronous; encoding peripheral stimuli

7

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

thalamus and cortex; synchronous

8

modulation of the thalamocortical loops generates eeg __

signatures of sleep

9

henry head experiment

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

10

henry head results

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

11

what do the henry head results suggest?

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

12

acute axonal degeneration: (3)

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

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 __

the PNS; the CNS

14

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

Ca; after injury; proteases (Calpain)

15

severing the axon prevents __

trafficking

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 __

NMNAT2; distal; Ca; mitochondria; internal Ca stores

17

Ca activates __ pathways

death

18

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

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

19

both schwann cells and macrophages secrete molecules essential for __

successful regeneration

20

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

laminin, fibronectin, collagens; extracellular matrix

21

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

integrins; intracellular signaling; growth

22

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

growth cones; cell adhesion molecules

23

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

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

24

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

schwann cell processes

25

Wallerian degeneration

macrophages eating myelin sheath slowly

26

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

gene expression; protein trafficking

27

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

actin and microtubule cytoskeleton

28

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

CNS

29

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

peripheral nerve graft

30

axon guidance is mediated by __ and __

chemoattraction and chemorepulsion

31

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

growth cones; axon guidance molecules

32

growth cones are dependent on __

receptors and concentration gradients of molecular cues

33

after denervation, original NMJ synpatic sites __

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

34

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

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

35

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

tropic and trophic

36

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

polyneuronal innervation

37

activity-dependent processes: __

polyneuronal innervation

38

also need activity-dependent refinement to eliminate __

aberrant synapses

39

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

survival; continued growth and differentiation; trophic interaction

40

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

neurotrophic factors; growth differentiation and survival

41

if there is a surplus of neurons born, __

fewer make connections

42

neurons that fail to __ are eliminated

connect with appropriate targets

43

NGF is an important

neurotropin

44

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

limited; large numbers of new neurons

45

3 barriers to CNS repair

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

46

glial cells actively __ in the CNS

inhibit axon regeneration

47

brain injury causes __ of glial precursors

local proliferation

48

glial scar is when __

glia infiltrate the site of injury and persist

49

regeneration is blocked for 3 reasons

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

50

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

epherins, semphorins, slit, and NogoA

51

in the adult brain, neurogenesis occurs __

in select areas

52

2 areas with high levels of neurogenesis in adult brain

olfactory bulb and hippocampus

53

new nerve cells are primarily __

interneurons

54

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

lateral ventricle (subventricular zone)

55

most new nerve cells __

die before they are integrated