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Neurobiology > Lecture 22 > Flashcards

Lecture 22 Flashcards

1
Q

__ neurons in the sleep cycle

A

thalamocortical

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2
Q

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

A

brainstem; thalamus and cortex

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3
Q

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

A

brainstem; thalamus; cortex

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4
Q

thalamocortical neurons exist in two states

A

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

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5
Q

the tonically active state occurs when the thalamocortical neurons are __

A

depolarized

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6
Q

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

A

asynchronous; encoding peripheral stimuli

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7
Q

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

A

thalamus and cortex; synchronous

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8
Q

modulation of the thalamocortical loops generates eeg __

A

signatures of sleep

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9
Q

henry head experiment

A

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

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10
Q

henry head results

A

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

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11
Q

what do the henry head results suggest?

A

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

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12
Q

acute axonal degeneration: (3)

A

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

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13
Q

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 __

A

the PNS; the CNS

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14
Q

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

A

Ca; after injury; proteases (Calpain)

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15
Q

severing the axon prevents __

A

trafficking

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16
Q

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 __

A

NMNAT2; distal; Ca; mitochondria; internal Ca stores

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17
Q

Ca activates __ pathways

A

death

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18
Q

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

A

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

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19
Q

both schwann cells and macrophages secrete molecules essential for __

A

successful regeneration

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20
Q

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

A

laminin, fibronectin, collagens; extracellular matrix

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21
Q

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

A

integrins; intracellular signaling; growth

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22
Q

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

A

growth cones; cell adhesion molecules

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23
Q

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

A

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

24
Q

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

A

schwann cell processes

25
Q

Wallerian degeneration

A

macrophages eating myelin sheath slowly

26
Q

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

A

gene expression; protein trafficking

27
Q

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

A

actin and microtubule cytoskeleton

28
Q

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

A

CNS

29
Q

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

A

peripheral nerve graft

30
Q

axon guidance is mediated by __ and __

A

chemoattraction and chemorepulsion

31
Q

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

A

growth cones; axon guidance molecules

32
Q

growth cones are dependent on __

A

receptors and concentration gradients of molecular cues

33
Q

after denervation, original NMJ synpatic sites __

A

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

34
Q

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

A

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

35
Q

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

A

tropic and trophic

36
Q

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

A

polyneuronal innervation

37
Q

activity-dependent processes: __

A

polyneuronal innervation

38
Q

also need activity-dependent refinement to eliminate __

A

aberrant synapses

39
Q

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

A

survival; continued growth and differentiation; trophic interaction

40
Q

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

A

neurotrophic factors; growth differentiation and survival

41
Q

if there is a surplus of neurons born, __

A

fewer make connections

42
Q

neurons that fail to __ are eliminated

A

connect with appropriate targets

43
Q

NGF is an important

A

neurotropin

44
Q

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

A

limited; large numbers of new neurons

45
Q

3 barriers to CNS repair

A

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

46
Q

glial cells actively __ in the CNS

A

inhibit axon regeneration

47
Q

brain injury causes __ of glial precursors

A

local proliferation

48
Q

glial scar is when __

A

glia infiltrate the site of injury and persist

49
Q

regeneration is blocked for 3 reasons

A

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

50
Q

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

A

epherins, semphorins, slit, and NogoA

51
Q

in the adult brain, neurogenesis occurs __

A

in select areas

52
Q

2 areas with high levels of neurogenesis in adult brain

A

olfactory bulb and hippocampus

53
Q

new nerve cells are primarily __

A

interneurons

54
Q

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

A

lateral ventricle (subventricular zone)

55
Q

most new nerve cells __

A

die before they are integrated

Neurobiology (16 decks)

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