hce_nsysu
115年
普通生物及生化概論
第 33 題
Long-term potentiation (LTP) represents a fundamental cellular mechanism underlying learning and memory. Which of the following best describes a critical requirement for the induction of early-phase LTP?
- A Sustained activation of NMDA receptors leading to $Ca^{2+}$ influx, which directly promotes rapid insertion of AMPA receptors into the postsynaptic membrane.
- B $Ca^{2+}$ influx through NMDA receptors following postsynaptic depolarization, which triggers the translocation of additional AMPA receptors to the postsynaptic membrane via calcium/calmodulin-dependent protein kinase II (CaMKII) signaling.
- C Increased presynaptic glutamate release caused by enhanced vesicle docking, which by itself is sufficient to maintain persistent synaptic potentiation.
- D Activation of postsynaptic glycine receptor chloride channels, which leads to the depolarization that relieves the $Mg^{2+}$ block of NMDA receptors.
- E Immediate activation of cAMP response element-binding protein (CREB)-dependent gene transcription in the absence of $Ca^{2+}$ influx, which primes neurons for later potentiation.
思路引導 VIP
若要讓一個神經元對未來的刺激反應更劇烈，就像是在門口增加更多的「收信箱」一樣。請思考：在麩胺酸釋放後，哪一種特定的離子必須先流入細胞充當「通報者」？而這個通報者進入細胞前，為什麼必須先讓細胞膜電位發生改變（去極化）才能成功「開門」呢？
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AI 詳解
AI 專屬家教
恭喜你準確地掌握了神經科學中學習與記憶的核心機制！這題能選對，代表你對突觸的可塑性有非常紮實的理解。在這道題目中，我們探討的是早期長時程增強作用 (Early-phase LTP) 的分子基礎。
鈣離子與信號轉導的關鍵角色
早期 LTP 的誘發關鍵在於突觸後膜的去極化，這會排除 NMDA 受體上的 $Mg^{2+}$ 阻斷，使 $Ca^{2+}$ 得以流入細胞內。這些鈣離子會與鈣調蛋白結合，進而活化 CaMKII (鈣離子/鈣調蛋白依賴性蛋白激酶 II)。這是一個至關重要的步驟，因為 CaMKII 會引發一系列訊息傳遞，促使儲存在細胞內的 AMPA 受體快速轉移並嵌入到突觸後膜上，增加神經元對麩胺酸 (Glutamate) 的敏感度。這解釋了為什麼選項 (B) 是最完整且正確的描述。
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