Long-term depression

Definition

Long-term depression (LTD) is a lasting decrease in the strength of synaptic transmission that occurs after low-frequency stimulation of a synapse. This process is important for synaptic plasticity, which is essential for learning and memory, as it helps to fine-tune neural circuits and strengthen certain connections while weakening others.

5 Must Know Facts For Your Next Test

1. LTD is typically induced by low-frequency stimulation, leading to a reduction in neurotransmitter release and changes in receptor sensitivity.
2. It plays a critical role in homeostatic plasticity, allowing the nervous system to adjust to changes in activity and maintain stability.
3. LTD can be specific to certain synapses, meaning that it allows for selective weakening of certain connections while preserving others.
4. Molecular mechanisms involved in LTD often include the activation of specific intracellular pathways, such as those involving calcium and protein phosphatases.
5. Research has shown that LTD may contribute to forgetting processes by diminishing the strength of irrelevant or outdated memories.

Review Questions

• How does long-term depression contribute to the concept of synaptic plasticity?
  • Long-term depression is an essential component of synaptic plasticity, as it allows for the weakening of synaptic connections that are less frequently activated. This process helps fine-tune neural circuits by promoting the removal of unnecessary or redundant connections, making space for stronger connections that reflect more relevant experiences. By balancing both long-term potentiation and long-term depression, synaptic plasticity supports the brain's ability to adapt to new information and experiences.
• Discuss the molecular mechanisms involved in long-term depression and how they differ from those in long-term potentiation.
  • The molecular mechanisms of long-term depression primarily involve calcium signaling and the activation of specific protein phosphatases that lead to decreased receptor sensitivity and reduced neurotransmitter release. In contrast, long-term potentiation relies on calcium influx that activates kinases to enhance receptor function and increase neurotransmitter release. This fundamental difference highlights how LTD and LTP work together to regulate synaptic strength based on neuronal activity patterns.
• Evaluate the implications of long-term depression on learning and memory processes, particularly regarding the balance between remembering and forgetting.
  • Long-term depression plays a crucial role in learning and memory by enabling the brain to selectively weaken connections associated with less relevant or outdated information. This selective weakening is vital for preventing cognitive overload and allows for more efficient memory storage by prioritizing important experiences. Evaluating this balance between remembering and forgetting underscores how LTD contributes not only to adaptability in learning but also to maintaining an updated cognitive framework, essential for effective decision-making and problem-solving.

Related terms

Long-term potentiation: A long-lasting increase in synaptic strength that occurs following high-frequency stimulation of a synapse, playing a crucial role in learning and memory.

Synaptic plasticity: The ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity, forming the basis for learning and memory.

Calcium signaling: The process by which calcium ions act as a signal within cells, influencing various cellular processes, including the induction of LTD and LTP.