Long-term depression

Definition

Long-term depression (LTD) is a long-lasting decrease in the efficacy of synaptic transmission, resulting from specific patterns of activity between neurons. This process is crucial for the regulation of synaptic strength, allowing for the fine-tuning of neural circuits, which is essential for learning and memory. LTD is considered a counterpart to long-term potentiation (LTP), and both processes play critical roles in synaptic plasticity, influencing how experiences shape behavior and learning.

5 Must Know Facts For Your Next Test

1. LTD is typically induced by low-frequency stimulation of presynaptic neurons, leading to a decrease in the postsynaptic neuron's response.
2. This process is believed to play a significant role in error correction during learning, helping to adjust and refine neural connections based on experience.
3. Calcium signaling is a crucial component of LTD; increased intracellular calcium levels can trigger signaling pathways that result in reduced synaptic strength.
4. LTD can contribute to competitive processes in learning, allowing less relevant information to be diminished in favor of more relevant experiences.
5. LTD has been implicated in various neurological disorders, suggesting that abnormal synaptic depression may contribute to cognitive deficits.

Review Questions

• How does long-term depression interact with long-term potentiation in the context of synaptic plasticity?
  • Long-term depression (LTD) and long-term potentiation (LTP) are opposing processes that regulate synaptic strength and plasticity. While LTP enhances synaptic efficacy through high-frequency stimulation, LTD reduces it through low-frequency stimulation. Together, they provide a balance that allows the nervous system to adaptively modify neural circuits based on experiences. This interplay is essential for encoding memories and learning, allowing the brain to prioritize relevant information while diminishing less important connections.
• Discuss how long-term depression plays a role in error correction during the learning process.
  • Long-term depression serves as an important mechanism for error correction in learning by reducing the strength of incorrect or less relevant neural connections. When new information contradicts previously learned material, LTD allows the brain to weaken those outdated associations, facilitating the formation of more accurate representations. This adaptive adjustment helps improve performance over time by refining synaptic connections based on feedback from experiences.
• Evaluate the implications of disrupted long-term depression mechanisms in neurological disorders related to cognitive deficits.
  • Disruptions in long-term depression mechanisms can significantly impact cognitive function and are linked to several neurological disorders such as Alzheimer's disease and schizophrenia. In these conditions, impaired LTD may lead to an inability to properly adjust synaptic connections, resulting in persistent incorrect associations or failure to learn new information effectively. This breakdown in synaptic plasticity can manifest as memory loss or cognitive decline, highlighting the critical role of LTD in maintaining healthy neural function and adaptive learning.

Related terms

Long-term potentiation (LTP): A long-lasting increase in synaptic strength following high-frequency stimulation of a synapse, which is essential for learning and memory.

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

Hebbian learning: A theory of synaptic plasticity that states that an increase in the activity of one neuron increases the likelihood of another neuron firing, often summarized as 'cells that fire together wire together.'