OCCTH 585 Neuro Questions & Answers Already Passed!!

Information flows through neurons from ____ to ____ in the neuron - Answer-dendrite; axon _____ bring a cell to threshold while _____ bring a cell further from threshold - Answer-EPSPs; 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? - Answer-when 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? - Answer-when 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? - Answer-when 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 inputsWhat can lead to collateral sprouting? - Answer-more 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? - Answer-no, 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? - Answer-neurotrophin (released by dendritic spines through APs) What are chemoattractants? - Answer-neurotrophins and other chemical signals that signal to a neuron to grow their collaterals in that direction What are chemorepellants? - Answer-chemical signals that signal to a neuron to grow their collaterals away from that direction What structures release chemoattractants and chemorepellants? - Answer-guide cells What is a growth cone? - Answer-a 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? - Answer-no, 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 developmentA large chemorepellant signal can lead to ____ ____ ____; exposure can also signal ____________________ - Answer-growth 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 _____ - Answer-20-25%; 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