In this installment, I will discuss long-term potentiation, or LTP. LTP is a process by which synaptic connections between neurons become stronger with frequent activation.

在本篇中，我將討論長期電位，即 LTP。LTP 是一個神經元之間的突觸連接隨著頻繁激活而變得更強的過程。

LTP is thought to be a way in which the brain changes in response to experience, and thus may be a mechanism underlying learning and memory. There are a number of ways in which LTP can occur.

LTP 被認為是大腦對經驗做出反應的一種方式，是以可能是學習和記憶的一種基礎機制。發生 LTP 有多種方式。

The best-known mechanism involves a receptor known as the NMDA receptor.

最著名的機制涉及一種被稱為 NMDA 受體的受體。

In NMDA receptor-dependent LTP, glutamate release first activates a subtype of glutamate receptor known as the AMPA receptor.

在 NMDA 受體依賴性 LTP 中，穀氨酸的釋放首先激活一種稱為 AMPA 受體的穀氨酸受體亞型。

NMDA receptors are found nearby these AMPA receptors, but are not activated by low levels of glutamate release because the ion channel of an NMDA receptor is blocked by a magnesium ion. If frequent action potentials cause greater stimulation of AMPA receptors, however, this will cause the postsynaptic neuron to the voltage-dependent magnesium blockage of the NMDA receptor to be removed, allowing calcium ions to flow in through the NMDA receptor.

NMDA 受體存在於這些 AMPA 受體附近，但不會被低水平的穀氨酸釋放激活，因為 NMDA 受體的離子通道被鎂離子阻斷。然而，如果頻繁的動作電位會對 AMPA 受體造成更大的刺激，這將導致突觸後神經元對 NMDA 受體的電壓依賴性鎂離子阻滯被解除，從而使鈣離子能夠通過 NMDA 受體流入。

This influx of calcium initiates cellular mechanisms that cause more AMPA receptors to be inserted into the neuron's membrane. The new AMPA receptors are also more responsive to glutamate, and allow more positively charged ions to enter the cell when activated.

鈣的流入會啟動細胞機制，使更多的 AMPA 受體插入神經元膜。新的 AMPA 受體對穀氨酸的反應也更靈敏，激活後可讓更多帶正電荷的離子進入細胞。

Now the postsynaptic cell is more sensitive to glutamate because it has more receptors to respond to it. Additionally, there are thought to be signals that travel back across the synapse to stimulate greater levels of glutamate release.

現在，突觸後細胞對穀氨酸更加敏感，因為它有更多的受體對穀氨酸做出反應。此外，人們還認為有一些信號會穿過突觸，刺激穀氨酸釋放到更高水平。

All this makes the synapse stronger and more likely to be activated in the future. This process is also associated with changes in gene transcription in the neuron, which can lead to the production of new receptors or modifications to the structure of the cell.

所有這些都會使突觸變得更強，更有可能在未來被激活。這一過程還與神經元中基因轉錄的變化有關，這可能導致產生新的受體或改變細胞結構。

These changes seem to be important for making the increased responsiveness of LTP long-lasting.

這些變化似乎對 LTP 反應能力的持久提高非常重要。