碩士 / 國立清華大學 / 生命科學系 / 90 / Short-term potentiation (STP) and long-term potentiation (LTP) are two forms of synaptic facilitation. Much of the experimental work concerns the possible roles of STP and LTP in memory formation. Both STP and LTP can be induced by high-frequency stimulation in hippocampal area CA1 that are the phases of population excitatory postsynaptic potential. Many studies of conditioned that they are the activity-dependent increase in synaptic efficacy and through chemical synapses. STP and LTP are considered to contribute to short-term memory and long-term memory storage.
Both cholinergic synapses and voltage-sensitive gap junctions but no NMDA receptors exist in the crayfish escape circuit. Coincidence detection mediated by voltage-sensitive gap junction has been reported in the LG escape circuit of crayfish. Both voltage-sensitive gap junction and NMDA receptor are the coincidence detectors. Previous work from our laboratory showed that low-voltage tetanus induced LTP can be mediated by this voltage-sensitive gap junction in the crayfish escape circuit.
Here I report that both STP and LTP can be induced by suprathreshold high-voltage tetanus. In the absence of cholinergic synapses, these two forms of potentiation can be induced suggest that these potentiation are mediated by electrical synapse. I propose that STP and LTP were expressed via independent mechanisms, although the calcium of extracellular and the depolarization of postsynaptic neuron played a important role in these two forms of synaptic facilitation. My results suggest that low-voltage tetanus and high-voltage tetanus involve two similar but different mechanism in LTP induction.
The low-frequency tetanus induced LTP result from presynaptic processes. Low frequency of weak repeated stimulation cannot induced LTP, indicate that crayfish will not change the sensitivity of response when weak stimulate is commonly happened. However, strong stimulation even with low frequency or with fewer number of stimulate still induce STP and LTP indicating increase the overall sensitivity of escape circuit not confined at active synapses.
| Identifer | oai:union.ndltd.org:TW/090NTHU0105047 |
| Date | January 2002 |
| Creators | Huei-Mei Shih, 施惠美 |
| Contributors | Shih-Rung Yeh, 葉世榮 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 37 |
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