OCCTH 585 Midterm Exam Study Set 3|
Questions with Complete Answers
neuroplasticity - ✔✔- change in the properties of neurotransmission
- change in cell properties
- structural/anatomical changes of cells
change in properties of neurotransmission - ✔✔- change in NT release
- change in post-synaptic potential size/shape
change in cell properties - ✔✔- size and shape
- electrical properties (resistance)
- leakiness
structural/anatomical changes of cells - ✔✔- re-growth of parts of the nervous
system (not there yet)
- growth of axons, dendrites, axonal collateral
unmasking - ✔✔immediate, exposure of pre-existing synapses resulting in functional
changes - synapses were always there, but may not of been functionally recognized
dendritic pruning - ✔✔retraction of unused bits (ex. dendritic spines/branches),
resulting in a loss in real estate and a decrease in energy expenditure - after un-masking
occurs, dendrites will wait for input, but it they don't receive any this process will take
place resulting in a reduction in cell volume impacting cell function
,collateral sprouting - ✔✔growth of new bits (axon branches), requiring time, to fill
vacancies on dendrites/target - process is activity dependent and produces functional
changes
how is growth is activity dependent? - ✔✔target cells send out signals for other cells
to grow towards them - the only way for a cell to grow towards the target cell is if it is
also active:
- active cells release NT and then "scoop" in excess NT - with this, they will bring in
chemicals from the target cell (neurotrophins/chemoattractants), attracting cell to grow
towards target
- dendritic spines release neurotrophins to stabalize the synapse - if the input cell dies,
the neurotrophins release into environment, attacting cells to fill in vacant space
can we stimulate collateral sprouting? - ✔✔yes, via high frequency and intensity
stimulation - tells the nervous system the input is important, because we are receiving a
lot of stimulation - so this drives anatomical and functional changes that support
efficacy of the stimulated system
neurogenesis - ✔✔formation of new neurons
neurogenesis in the mature CNS - ✔✔- dentate gyrus of the hippocampus
- corpus collosum - olfactory bulb
- neural glial cells - astrocytes
mechanism/control of neurogenesis - ✔✔VERY COMPLEX
- Proliferation (if not well controlled = tumours)
- Migration (need to move to intended target, survive hostile environment from immune
system)
,- Differentiation (need to differentiate from stem cell to functional neuron capable of
making connections)
**new neurons survive in enriched environments, glucocorticoids (stress) decrease
proliferation, estrogen increases cell proliferation
limitations of neurogenesis in mature CNS - ✔✔- happens in embryology
- need to navigate around pre-existing and formed structures
- hormones and environment impact and influence how cells shift from one stage to the
next
- complicated by embedding a new cell into a system that we have created over a
lifetime
axonal growth during embryology - ✔✔- chemoattractants and chemorepellants
work together to repel axon from wrong target and attract to correct target
- neurons are in growth phase; grow with a growth cone
- guide cells are present
- hormone balance is critical
- guidance molecules present in high concentrations
chemoattractant - ✔✔a diffusible molecule that acts over a distance to attract
growing axons
chemorepellant - ✔✔a diffusible molecule that acts over a distance to repel growing
axons
growth cone - ✔✔the specialized structure specific for growth - filipodium
(extensions) go out in all directions searching for chemoattractants, which will cause it
to grow in a dedicated direction to the target
, impact of hormones on baby during embryology - ✔✔important for timing of growth
events, and the responsiveness of the neuron
guidance molecules - ✔✔- netrin
- slit
- ephrin
- semaphorin
netrin - ✔✔growth promoter/chemoattractant
slit - ✔✔both a chemoattractant and a chemorepellant - depends on the cell that is
receiving the signal - can also switch depending on stage of development (bringing an
axon to it, then repelling it)
ephrin and semaphorin - ✔✔chemorepellants - in high concentration in the adult
nervous system
impact of high concentration of chemorepellant - ✔✔- causes growth cone to
collapse
- can stimulate collateral - increasing axonal growth in other directions
what happens in embryologic neurogenesis that doesn't translate to adults? - ✔✔-
some chemicals don't exist in adults
- neurons are far less responsive (primary purpose is functional not growth)
- no guide cells to enable long distance growth to a target
Questions with Complete Answers
neuroplasticity - ✔✔- change in the properties of neurotransmission
- change in cell properties
- structural/anatomical changes of cells
change in properties of neurotransmission - ✔✔- change in NT release
- change in post-synaptic potential size/shape
change in cell properties - ✔✔- size and shape
- electrical properties (resistance)
- leakiness
structural/anatomical changes of cells - ✔✔- re-growth of parts of the nervous
system (not there yet)
- growth of axons, dendrites, axonal collateral
unmasking - ✔✔immediate, exposure of pre-existing synapses resulting in functional
changes - synapses were always there, but may not of been functionally recognized
dendritic pruning - ✔✔retraction of unused bits (ex. dendritic spines/branches),
resulting in a loss in real estate and a decrease in energy expenditure - after un-masking
occurs, dendrites will wait for input, but it they don't receive any this process will take
place resulting in a reduction in cell volume impacting cell function
,collateral sprouting - ✔✔growth of new bits (axon branches), requiring time, to fill
vacancies on dendrites/target - process is activity dependent and produces functional
changes
how is growth is activity dependent? - ✔✔target cells send out signals for other cells
to grow towards them - the only way for a cell to grow towards the target cell is if it is
also active:
- active cells release NT and then "scoop" in excess NT - with this, they will bring in
chemicals from the target cell (neurotrophins/chemoattractants), attracting cell to grow
towards target
- dendritic spines release neurotrophins to stabalize the synapse - if the input cell dies,
the neurotrophins release into environment, attacting cells to fill in vacant space
can we stimulate collateral sprouting? - ✔✔yes, via high frequency and intensity
stimulation - tells the nervous system the input is important, because we are receiving a
lot of stimulation - so this drives anatomical and functional changes that support
efficacy of the stimulated system
neurogenesis - ✔✔formation of new neurons
neurogenesis in the mature CNS - ✔✔- dentate gyrus of the hippocampus
- corpus collosum - olfactory bulb
- neural glial cells - astrocytes
mechanism/control of neurogenesis - ✔✔VERY COMPLEX
- Proliferation (if not well controlled = tumours)
- Migration (need to move to intended target, survive hostile environment from immune
system)
,- Differentiation (need to differentiate from stem cell to functional neuron capable of
making connections)
**new neurons survive in enriched environments, glucocorticoids (stress) decrease
proliferation, estrogen increases cell proliferation
limitations of neurogenesis in mature CNS - ✔✔- happens in embryology
- need to navigate around pre-existing and formed structures
- hormones and environment impact and influence how cells shift from one stage to the
next
- complicated by embedding a new cell into a system that we have created over a
lifetime
axonal growth during embryology - ✔✔- chemoattractants and chemorepellants
work together to repel axon from wrong target and attract to correct target
- neurons are in growth phase; grow with a growth cone
- guide cells are present
- hormone balance is critical
- guidance molecules present in high concentrations
chemoattractant - ✔✔a diffusible molecule that acts over a distance to attract
growing axons
chemorepellant - ✔✔a diffusible molecule that acts over a distance to repel growing
axons
growth cone - ✔✔the specialized structure specific for growth - filipodium
(extensions) go out in all directions searching for chemoattractants, which will cause it
to grow in a dedicated direction to the target
, impact of hormones on baby during embryology - ✔✔important for timing of growth
events, and the responsiveness of the neuron
guidance molecules - ✔✔- netrin
- slit
- ephrin
- semaphorin
netrin - ✔✔growth promoter/chemoattractant
slit - ✔✔both a chemoattractant and a chemorepellant - depends on the cell that is
receiving the signal - can also switch depending on stage of development (bringing an
axon to it, then repelling it)
ephrin and semaphorin - ✔✔chemorepellants - in high concentration in the adult
nervous system
impact of high concentration of chemorepellant - ✔✔- causes growth cone to
collapse
- can stimulate collateral - increasing axonal growth in other directions
what happens in embryologic neurogenesis that doesn't translate to adults? - ✔✔-
some chemicals don't exist in adults
- neurons are far less responsive (primary purpose is functional not growth)
- no guide cells to enable long distance growth to a target
