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6 Cards in this Set
- Front
- Back
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*Describe the mechanisms of habituation in Aplysia. |
After many repetitions of touching the siphon gill, the sensory neuron continues sending action potentials to the motor neuron, but there is decreased release of neurotransmitters at the synapse, so the response declines (habituates). |
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*Describe the mechanisms of sensitization in Aplysia. |
Strong stimulation on the skin activates a facilitating interneuron to release serotonin onto the presynaptic terminals of many sensory neurons. Serotonin blocks potassium channels in these membranes. Since potassium can't rush out of the cell, the cell is much slower to repolarize. This provides more time for the presynaptic terminal to release its neurotransmitter. Repeating this process causes the sensory neuron to create new proteins that produce long-term sensitization. |
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*Describe the characteristics of long-term potentiation (LTP). |
Specificity (only active synapses are strengthened), cooperativity (simultaneous stimulation is more powerful than stimulation by just one axon), and associativity (pairing weak input with stronger input strengthens the long-term response of the weaker input). |
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*Describe the characteristics of long-term depression (LTD). |
A compensatory process where as one synapse is strengthened, another one is weakened. |
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*Describe the roles of AMPA and NMDA receptors in LTP. |
When glutamate massively stimulates AMPA receptors, the resulting depolarization allows glutamate to stimulate nearby NMDA receptors too. This lets calcium enter the cell, which sets in motion changes to the cell making dendrites more receptive to glutamate at AMPA receptors in the future. |
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**Drugs that block NMDA synapses: |
prevent the establishment of LTP |
