2-Minute Neuroscience: Long-Term Depression (LTD)
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  • Release Date: 2024-04-07
Playlist
  • depression
  • AMPA
  • NMDA
  • brain
  • neuron
  • synapse
Video Introduction

The content is sourced from: https://youtu.be/B7ig6sIwIC8

Long-term depression, or LTD, is a process by which synaptic connections between neurons are weakened. Although the functions of LTD are not completely understood, it may be important to memory formation---perhaps by resetting previous synaptic changes to allow for new memories to be formed via long-term potentiation (LTP). In this video, I discuss the best understood mechanism underlying LTD, which involves AMPA and NMDA glutamate receptors.[1]

LTD is a process by which synaptic connections between neurons become weaker. It is the opposing process to long-term potentiation. Although the functions of LTD are not completely understood, it’s thought to be important to memory formation, perhaps by resetting previous synaptic changes to allow for new memories to be formed via long-term potentiation.

There are several different mechanisms by which LTD may occur, but the best understood of them involves the same glutamate receptors involved in long-term potentiation: NMDA and AMPA receptors. NMDA receptors are typically blocked by a magnesium ion, which is only removed if the postsynaptic neuron becomes sufficiently depolarized as can occur through activation of the AMPA receptor; when the block is removed, calcium is able to flow into the neuron, causing further depolarization. While long-term potentiation typically occurs after brief but high-intensity stimulation of a post-synaptic neuron, LTD can be caused by prolonged low-intensity stimulation or stimulation that occurs after the firing of an action potential. With the type of modest stimulation that results in LTD, there is not enough depolarization to cause widespread removal of the magnesium blockage of the NMDA receptor. However, there is enough to cause some NMDA receptors to allow calcium into the cell. This low level of calcium is insufficient to activate the enzymes that facilitate long-term potentiation, but it is thought to activate a cellular cascade that causes the removal of AMPA receptors. This reduces the number of glutamate receptors on the postsynaptic neuron and weakens the synapse.

LTD may also result in other changes that decrease the strength of synapses, like a decrease in the amount of glutamate released from the presynaptic neuron, and it also can involve other receptors like metabotropic glutamate receptors or other neurotransmitter receptors altogether. 

References
  1. Kandel ER, Schwartz JH, Jessell TM 2000. Principles of Neural Science, 5th ed. McGraw-Hill, New York.
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Challenged, N. 2-Minute Neuroscience: Long-Term Depression (LTD). Encyclopedia. Available online: https://encyclopedia.pub/video/video_detail/1181 (accessed on 25 May 2024).
Challenged N. 2-Minute Neuroscience: Long-Term Depression (LTD). Encyclopedia. Available at: https://encyclopedia.pub/video/video_detail/1181. Accessed May 25, 2024.
Challenged, Neuroscientifically. "2-Minute Neuroscience: Long-Term Depression (LTD)" Encyclopedia, https://encyclopedia.pub/video/video_detail/1181 (accessed May 25, 2024).
Challenged, N. (2024, April 07). 2-Minute Neuroscience: Long-Term Depression (LTD). In Encyclopedia. https://encyclopedia.pub/video/video_detail/1181
Challenged, Neuroscientifically. "2-Minute Neuroscience: Long-Term Depression (LTD)." Encyclopedia. Web. 07 April, 2024.
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