Term
| What synaptic changes allow for memory formation and storage? |
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Definition
| Memory formation and storage occurs by alteration in the strength of synaptic contacts between neurons. |
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Term
| Where in the brain can synapses be strengthens or weakened? |
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Definition
| Synapses in the basal ganglia, cerebellum, hippocampus, and neocortex can be strengthened and weakend. |
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Term
| What is the process of of strengthening neurons known as? |
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Definition
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Term
| What cells are the output cells for the cerebellum? |
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Definition
| Neurons in the deep nuclei. |
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Term
| What do Purkinje cells do and what NT do they use to accomplish this task? |
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Definition
| Purkinje cells inhibit the neurons of the deep cerebellar nuclei by releasing inhibitory GABA. |
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Term
| What are the two major sources of excitatory synaptic input for Purkinje cells> |
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Definition
-Parallel fibers (axons of the granule cells, a local circuit neuron of the cerebellar cortex)
-Climbing fibers (axons from neurons in the inferior olive) |
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Term
| How many synaptic inputs does a Purkinje cell receive from parallel fibers? |
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Definition
| Purkinje cells receive synaptic input from thousand of parallel fibers, each of which makes a single synaptic contact with the Purkinje cell. |
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Term
| How many synaptic inputs does a Purkinje cell receive from climbing fibers? |
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Definition
| Purkinje fibers receive multiple synaptic contacts from one climbing fiber. |
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Term
| How strong is the postsynaptic effect of parallel fiber activation? |
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Definition
| The postsynaptic effect of parallel fiber activation is relatively weak. |
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Term
| How strong is the postsynaptic activation of a climbing fiber. |
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Definition
| Climbing fiber postsynaptic activation is strong, creating a large, long, compound EPSP which is reflective of the glutamate release from the multiple synaptic contacts made by the climbing fiber. |
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Term
| How is long term depression triggered? |
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Definition
| By simultaneous activation of climbing and parallel fibers creating overlapping simple and complex spike firing. |
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Term
| How are voltage gated calcium channels of the dendritic membrane of the Purkinje cell activated? |
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Definition
| The strong postsynaptic excitation excitation of climbing cells activates the voltage gated calcium channels. |
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Term
| In regards to LTD, what releases glutamate and what is the immediate effect of this release? |
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Definition
| Glutamate is released by synaptic terminals of parallel fibers and activates AMPA type glutamate receptors and also activates a subtype of metabotropic glutamate receptor. |
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Term
| In terms of LTD what effect does activation fo the metabotropic glutamate receptor have on the Purkinje cell? |
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Definition
| The activated metabotrophic glutamate receptor stimulates PLC which cleaves PIP2 liberating 2 additional second messengers DAG and IP3. DAG stimulates protein kinase C and IP3 stimulates release of calcium from intracellular stores. |
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Term
| What is the effect of increased intracellular calcium and PKC activation? |
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Definition
| Increased intracellular calcium and increase PKC depresses the postsynaptic response to glutamate released form the parallel fiber synaptic terminals. The climbing fiber synapses are not affected. |
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Term
| What are the two theories of memory consolidation? |
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Definition
Intermediate memory-The hippocampus or closely related medial temporal lobe structure provide a site for intermediate term storage of memory. Memories are transferred into the hippocampus from the short term memory store. These memories are later transferred back to neorcortical areas for permanent (long-term) storage.
-memory index- hippocampus or closely related medial temporal lobe structures do not actually store memories instead they store an index of all the neocortical areas where the multiple aspects of memories are stored. Once memory is fully consolidated the index is no longer needed. |
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Term
| LTD decreases Purkinje cell simple spike firing leading to what? |
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Definition
| A decrease in inhibition of neurons of the deep nuclei. This decrease in inhibition leads to increase in their firing rate, and thereby increases the output from the cerebellum leading to motor learning. |
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Term
| In long term depression, what is the effect of increased intracellular calcium and PKC activation? |
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Definition
| Decreases the post synaptic response to glutamate released from the parallel fibers. This leads to a long lasting decrease in firing of simple cell spikes from the Purkinje cell. |
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