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Year 2: Neurobiology II > Lecture 8: Neuroplasticity > Flashcards

Lecture 8: Neuroplasticity Flashcards

1
Q

what are the 10 principles of neuroplasticity ranked from most to least important

A
  1. Salience
  2. specificity
  3. repetition
  4. intensity
  5. use it and improve it
  6. use it or lose it
  7. time matters
  8. interference
  9. age matters
  10. transference
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2
Q

what is the principle of interference with neuroplasticity

A

sometimes new plasticity can be delayed

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3
Q

definition of neuroplasticity

A

ability of neural circuirs to change through growth and reorganization

naturally happens with development

can be used for specific activity guided training or rehab

can be adaptive or maladaptive

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4
Q

describe the natural development of the nervous system

A

stem cells align along the ventricular wall and central canal of the spinal cord

the cells differentiate to either glioblasts or neuroblasts

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5
Q

for the stem cells that differentiate into glioblasts, what happens next

A

radial glial cells (directly merging with the pia mater) form the scaffold and the other 4 types of glia cells are in the CNS

radial glial cells are first to develop

other 4 types of glial cells develop after neurons

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6
Q

for the stem cells that differentiate into neuroblasts, what happens next

A

they mainly migrate along the radial glial scaffold; these neurons form a columnar functional unit

some migrate horizontally after climbing the glial process; these are responsible for coordinating and modulating functions

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7
Q

what mechanism is post natal neuroplasticity mainly through

A

neuroblasts that migrate horizontally after climbing the glial process (responsible for coordinating and modulating function)

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8
Q

what is a neurite

A

extension from the neuron soma/cell body

defines the neuron type and function

in the beginning, neuroblasts develop neurites without differentiation

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9
Q

types of neurites , where to find them/what neurons generally fall into the category

A

multipolar: UMNs and LMNs and most interneurons

pseudounipolar: DRG, sensory neurons

Bipolar: olfactor receptor neurons, visual pathway, some interneurons

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10
Q

describe how the polarity of neurons works

A

they have functionally distinct proteins that are attracted to neurite tips by directional stimuli

works via chemoattraction and chemorepulsion

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11
Q

where can you find neurotrophins/how do they work (chemoattraction factors)

A

peripheral process of sensory neurons in the DRG

different target cells secrete different neurotrophins (called cytokines)

these send signals to different peripheral processes that conduct specific sensory modalities

function = transported back to the somata for the survival of the neurons (block apoptosis)

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12
Q

purpose/function of chemorepulsion

A

still through different cytokines; used to avoid abnormal interactions

self avoidance = intra-neuronal repulsion (dendrites of same neuron)

tiling = inter-neuronal repulsion (dendrites of different neurons)

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13
Q

how do chemo- repulsion/attraction control the direction of the neuron signals

A

chemoattraction = direction of the neurite extension

chemorepulsion = turning point along the extension

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14
Q

describe how CN II is an example of the balance of chemo repulsion/attraction

A

axons of ganglionic cells from the temporal retina extend ipsilaterally

axons of ganglionic cells from the nasal retina cross over to form optic chiasm

both chemoattraction and repulsion are at play

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15
Q

what gene defines the development of external genitalia

A

SRY gene on the Y chromosome

if expressed = male

if female, there is no SRY gene (XX chromosomes) or the SRY is mutated and non functional (XY)

male external genitalia if SRY is inserted into the father copy of X chromosome

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16
Q

describe the relationship/importance of male genitalia and sec hormones related to brain development

A

all hormones synthesized from cholesterol

only male sex hormones surge in the fetal brain; male and female both have active hormones but only females have this fetal surge

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17
Q

describe the phases of sexual hormones related to brain development in males vs females

A

male brain has 2 phases: prenatal and puberty

females only have 1 phase: puberty phase

differentially developed brains define different behaviors in males vs females

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18
Q

examples of how differentially developed brains define different behaviors

A

sexual activities = different LMN pools for mm and reflex

violence (in amygdala) = males have fewer astrocytes to insulate and inhibit neurons thus they tend to be more violent

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19
Q

sexual hormones improve genesis of what

A

neurites

dendritogenesis for dendrites

20
Q

what is spinogenesis

A

spine sprouting along dendrites

dendritic spines = major synaptic points

i.e. pyramidal cells, medium spiny neurons, purkinje cells, etc

stimulated by sex hormones

21
Q

describe the findings of oxytocin and ADH levels in prairie voles/montane voles and how it relates to behavior

A

oxytocin
- prairie = found in prefrontal cortex, caudate, putamen, and nucleus accumbens

  • this is NOT true of montane voles

ADH
- prairie = ventral pallidum
- montane = lateral septal nucleus

behavior
- prairie = MONOGAMY
- montane = POLYGAMY

22
Q

male brain larger areas and the effects this causes

A

orbitofrontal cortex = analysis of results

corpus callosum = more cross talking, but harder stroke recovery

amygdala = more fights/violence

23
Q

female brain larger areas and the effects this causes

A

limbic lobe = more emotion

olfactory system = more sensation related to smell

SMA = like to work more?

hippocampus (smaller??) = more challenge with spatial orientation

24
Q

stages of synaptogenesis

A

early stage = axons extend to target structures under over amount of neurotrophins; axons mainly extend to dendrites, other axons, cell bodies, and target cells

synapses are formed by complex proteins (electric vs chemical)

late stage = synapse pruning if not strengthened

25
Q

what are the types of receptors on the postsynaptic membrane and their functions

A

AMPA receptor: ligand gated ion channel pending on presynaptic stimuli intensity; depolarization of postsynaptic membrane changes NMDA receptor conformation

NMDA receptor: Ca2+ channel is blocked by Mg2+

26
Q

how does ca2+ concentration in the postsynaptoc membrane affect the functions of the Ca2+

A

if above 5microM = activate kinase, transfer more AMPA to postsynaptic membrane; this strengthens the synapse (long term potentiation/LTP)

if below 1 microM = activate phosphatase, endocytosis of AMPA from postsynaptic membrane; pruning the synapse (long term depression/LTD)

27
Q

describe the critical stage of development of synapses/myelogenesis

A

birth = guided extension of axons

2 years = over amount of synapses

6 years = synapses are pruned; mature neural connecting network

*myelogenesis = myelination happens until late 20s

28
Q

what is the importance of pruning og synapses

A

spatiotemporal summation must be unified

each neuron gives off an output like morse code, each conveys a different meaning

there can be more than 1 menaing (i.e. mirror neurons and context dependent coding)

without pruning and after pruning can encode entirely different meanings

29
Q

mechanisms of pruning

A

long term potentiation and long term depression

30
Q

what is adult neurogenesis

A

more common in lower level animals

examples:
- regrowth of tails on lizards
- growth of eyes and brain in goldfish
- refresh caudate nucleus to learn sons in songbird

31
Q

where in the brain can you find stem cells

A

dentate gyrus of hippocampus and subventricular zone (septal nuclei)

32
Q

how do blast cells migrate

A

along radial glial processes then horizontal transfer

neuroblasts
- only for granule cells in hippocampus
- granule and periglomerular cells in olfactory bulb, rostral migration system

glioblasts
- mainly oligodendrocytes

33
Q

concentration of 14C in individuals born in 1952 vs 1968

A

1952
- no 14C in neurons = limited regenerating neurons in lifespan
- slight increase in 14C in glial cells = limited gliogenesis to replace lost glia

1968
- high concentration of 14C in neurons = limited replacement of neurons in lifespan
- slight decrease 14C in glial cells = limited gliogenesis to replace lost glia

34
Q

what is a diaschisis

A

neuropathology after nervous system injury

local injury results in both local and distant functional loss

34
Q

what is a connectome

A

nervous system functions through circuitry called a connectomeq

35
Q

MCA stroke; explain the diaschisis

A

whole brain functions are affected

occipital functional loss

L hemineglect

35
Q

timeframe for neuroplasticity with motor functions

A

3 months

36
Q

3 types of neuroplasticities and their prognosis **

A

peripheral axon injury = potential for full regrowth

in CNS, activating glia, loss of neurons and loss of function

in CNS activating glia, rarely neurogenesis for lost neurons, restoring functions

37
Q

why might there be slow reparation/regeneration of axons in the CNS

A

disruption of blood brain barrier after CNS injury = recruits glia and lasts for weeks

invasion of immune cells that lasts months

both contribute to glial scar formation; this may completely block regeneration of axons

38
Q

what is chromatolysis

A

death of neurons

no neurotrophins transported back to the cell bod

39
Q

describe the neuroplasticity post injury/loss of BUEs when using BLEs for ADLs

A

functional MRI show activated regions for LE motor functions AND the motor region for BUEs (improved fine motor control of the toes)

40
Q

describe the changes in brain pathways associated with blind people using Braille

A

braille reading in trained blind patients increased activities of the visual cortex

connections were restructured

increased connections with somatosensory cortex

decreased connections to dorsal/ventral streams and motor cortex

41
Q

describe how the use it or lose it principle of neuroplasticity pertains to the use of braille

A

monitoring of the 1st dorsal interosseous mm of a braille proofreader showed decreased motor presentation following a 10 day break from work but then a return to normal levels after 1 week of work again

reversible principle of therapeutic exercise

42
Q

describe the S1 presentation after electric stimulation of the ulnar and median nerve of untrained subjects vs skilled musicians

A

skilled musicians = larger representation

43
Q
A

Year 2: Neurobiology II (10 decks)

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