OCCTH 585 Neuro Exam Questions and Answers
Information flows through neurons from ____ to ____ in the neuron - Answerdendrite;
axon
/._____ bring a cell to threshold while _____ bring a cell further from threshold -
AnswerEPSPs; IPSPs
/.What 3 main things is neuroplasticity capable of? - Answer- changing the properties of
neurotransmission
- changes in cell properties
- structural/ anatomical changes of cells
/.How does neuroplasticity change the properties of neurotransmission? (2) - Answer-
change in transmitter size
- change in PSP size or shape
/.How does neuroplasticity change the properties of cells? (3) - Answer- size and shape
- electrical properties (resistance)
- "leakiness" of membrane
/.What is unmasking? - Answerwhen an injury, event, or illness eliminates the inputs
that a neuron most commonly responds to (i.e. blue --> blue region of brain), the neuron
will become more responsive to the other inputs on the neuron (i.e. yellow --> yellow
region of brain) and that new representation will increase; is immediate, involves
exposure of pre-existing synapses, and creates functional changes in the cell
/.What is dendritic pruning? - Answerwhen dendrites with no active synapses are
retracted to reduce the amount of resources wasted to keep those useless dendrites
alive; changes cellular properties (size and shape) and creates as 'loss of real estate',
decreases energy expenditure
/.What is collateral sprouting? - Answerwhen neurons sprout new synapses on bare
dendrites (either after pruning of dead synapses or less used working ones) leading the
cell to become more responsive to those new inputs
/.What can lead to collateral sprouting? - Answermore stimulation; higher representation
is driven by high rates of APs
/.What are the 6 mechanisms of collateral sprouting? - Answer- growth of new bits
- requires time
- fill vacancy OR push less used synapses out of the way
- activity dependent
- produces functional changes
,/.Do neurons have to be close to the "free real estate" in order to make new collaterals?
Do they need to already be involved with it? - Answerno, the closest ones will usually
get there first, but the axons can grow out 1-2cm to form a connection (any further =
stuff in the way, would take too long and die); no
/.What signals to other neurons that there is space to form new collaterals and guides
them to it? - Answerneurotrophin (released by dendritic spines through APs)
/.What are chemoattractants? - Answerneurotrophins and other chemical signals that
signal to a neuron to grow their collaterals in that direction
/.What are chemorepellants? - Answerchemical signals that signal to a neuron to grow
their collaterals away from that direction
/.What structures release chemoattractants and chemorepellants? - Answerguide cells
/.What is a growth cone? - Answera specialized structure at the end of the axon that has
filopodia that branch out in multiple directions to look for chemoattractive and
chemorepellant signals
/.Are neurons always responsive to guidance molecules? - Answerno, they are time-
locked based on the developmental clock of the embryo; some guidance molecules can
be both a chemoattractant and a chemorepellant depending on the embryo's current
stage of development
/.A large chemorepellant signal can lead to ____ ____ ____; exposure can also signal
____________________ - Answergrowth cone collapse; growth of filipodia off growth of
different spots of the neuron
/.Where are new neurons produced? (3) - Answer- subventricular zone (olfactory)
- dentrate gyrus of hippocampus (memory)
- Cerebral cortex
/.What are neurons and neurogenesis' roles in learning and memory? (3) - Answer-
undergo synaptic plasticity to retain memory
- can become "locked" for longterm memory
- can be replaced to allow new learning
/.___-___% of neurons in the hippocampus are replaced _____ - Answer20-25%;
monthly
/.What types of cells can stem cells turn into? - Answer- oligodendrocyte
- astrocyte
- neuron
, /.What things determine the type of cell that stem cells differentiate into? (2) - Answer-
level of hormones (estrogen increases, glucocorticoids decrease)
- environmental factors (in CNS, most often are astrocytes; neurons survive longer in
enriched environment)
/.What barriers do we face in attempting to direct stem cells to produce neurons needed
to repair injuries? (6) - Answer- nervous system laid out first in embryos; difficult to build
around everything else in adults
- difficult to replicate static environment needed for neurons to be generated
- difficult to get cells to go to the repair location (no guide cells)
- migration and differentiation occur simultaneously
- don't integrate well and will eventually die
- if stem cells are poorly activated, a tumor can be created
/.What is different about mature neurons vs embryonic neurons? - Answer- many cues
no longer produced
- cells, especially neurons, are no longer responsive
- guide cells no longer exist
/.What 7 things occur in the nervous system following an injury? - Answer- terminal
degeneration
- Wallerian degeneration
- myelin debris
- macrophage infiltration
- chromatolysis
- retraction of synaptic terminals
- degeneration
ALL HAPPENS SIMULTANEOUSLY
/.What is Wallerian degeneration? - Answeraxon distal to injury degenerates because it
is cut off from the cell body
/.Why is myelin debris created? - Answerthe part of the axon it is on degenerated, so it
is no longer needed
/.Why does macrophage infiltration occur? - Answerto clean up the myelin debris
/.What is chromatolysis? - Answerdispersion of Nissl substance and swelling of the cell
body due to high rate of protein production in order to attempt to repair in the injured
neuron
/.What is retrograde degeneration? - Answerloss of the proximal portion to the lesion
after an injury to the axon
/.What is anterograde degeneration? - Answerloss of the distal portion to the lesion after
an injury to the axon
Information flows through neurons from ____ to ____ in the neuron - Answerdendrite;
axon
/._____ bring a cell to threshold while _____ bring a cell further from threshold -
AnswerEPSPs; IPSPs
/.What 3 main things is neuroplasticity capable of? - Answer- changing the properties of
neurotransmission
- changes in cell properties
- structural/ anatomical changes of cells
/.How does neuroplasticity change the properties of neurotransmission? (2) - Answer-
change in transmitter size
- change in PSP size or shape
/.How does neuroplasticity change the properties of cells? (3) - Answer- size and shape
- electrical properties (resistance)
- "leakiness" of membrane
/.What is unmasking? - Answerwhen an injury, event, or illness eliminates the inputs
that a neuron most commonly responds to (i.e. blue --> blue region of brain), the neuron
will become more responsive to the other inputs on the neuron (i.e. yellow --> yellow
region of brain) and that new representation will increase; is immediate, involves
exposure of pre-existing synapses, and creates functional changes in the cell
/.What is dendritic pruning? - Answerwhen dendrites with no active synapses are
retracted to reduce the amount of resources wasted to keep those useless dendrites
alive; changes cellular properties (size and shape) and creates as 'loss of real estate',
decreases energy expenditure
/.What is collateral sprouting? - Answerwhen neurons sprout new synapses on bare
dendrites (either after pruning of dead synapses or less used working ones) leading the
cell to become more responsive to those new inputs
/.What can lead to collateral sprouting? - Answermore stimulation; higher representation
is driven by high rates of APs
/.What are the 6 mechanisms of collateral sprouting? - Answer- growth of new bits
- requires time
- fill vacancy OR push less used synapses out of the way
- activity dependent
- produces functional changes
,/.Do neurons have to be close to the "free real estate" in order to make new collaterals?
Do they need to already be involved with it? - Answerno, the closest ones will usually
get there first, but the axons can grow out 1-2cm to form a connection (any further =
stuff in the way, would take too long and die); no
/.What signals to other neurons that there is space to form new collaterals and guides
them to it? - Answerneurotrophin (released by dendritic spines through APs)
/.What are chemoattractants? - Answerneurotrophins and other chemical signals that
signal to a neuron to grow their collaterals in that direction
/.What are chemorepellants? - Answerchemical signals that signal to a neuron to grow
their collaterals away from that direction
/.What structures release chemoattractants and chemorepellants? - Answerguide cells
/.What is a growth cone? - Answera specialized structure at the end of the axon that has
filopodia that branch out in multiple directions to look for chemoattractive and
chemorepellant signals
/.Are neurons always responsive to guidance molecules? - Answerno, they are time-
locked based on the developmental clock of the embryo; some guidance molecules can
be both a chemoattractant and a chemorepellant depending on the embryo's current
stage of development
/.A large chemorepellant signal can lead to ____ ____ ____; exposure can also signal
____________________ - Answergrowth cone collapse; growth of filipodia off growth of
different spots of the neuron
/.Where are new neurons produced? (3) - Answer- subventricular zone (olfactory)
- dentrate gyrus of hippocampus (memory)
- Cerebral cortex
/.What are neurons and neurogenesis' roles in learning and memory? (3) - Answer-
undergo synaptic plasticity to retain memory
- can become "locked" for longterm memory
- can be replaced to allow new learning
/.___-___% of neurons in the hippocampus are replaced _____ - Answer20-25%;
monthly
/.What types of cells can stem cells turn into? - Answer- oligodendrocyte
- astrocyte
- neuron
, /.What things determine the type of cell that stem cells differentiate into? (2) - Answer-
level of hormones (estrogen increases, glucocorticoids decrease)
- environmental factors (in CNS, most often are astrocytes; neurons survive longer in
enriched environment)
/.What barriers do we face in attempting to direct stem cells to produce neurons needed
to repair injuries? (6) - Answer- nervous system laid out first in embryos; difficult to build
around everything else in adults
- difficult to replicate static environment needed for neurons to be generated
- difficult to get cells to go to the repair location (no guide cells)
- migration and differentiation occur simultaneously
- don't integrate well and will eventually die
- if stem cells are poorly activated, a tumor can be created
/.What is different about mature neurons vs embryonic neurons? - Answer- many cues
no longer produced
- cells, especially neurons, are no longer responsive
- guide cells no longer exist
/.What 7 things occur in the nervous system following an injury? - Answer- terminal
degeneration
- Wallerian degeneration
- myelin debris
- macrophage infiltration
- chromatolysis
- retraction of synaptic terminals
- degeneration
ALL HAPPENS SIMULTANEOUSLY
/.What is Wallerian degeneration? - Answeraxon distal to injury degenerates because it
is cut off from the cell body
/.Why is myelin debris created? - Answerthe part of the axon it is on degenerated, so it
is no longer needed
/.Why does macrophage infiltration occur? - Answerto clean up the myelin debris
/.What is chromatolysis? - Answerdispersion of Nissl substance and swelling of the cell
body due to high rate of protein production in order to attempt to repair in the injured
neuron
/.What is retrograde degeneration? - Answerloss of the proximal portion to the lesion
after an injury to the axon
/.What is anterograde degeneration? - Answerloss of the distal portion to the lesion after
an injury to the axon
