long-term depression

(noun)

a long-term weakening of a synaptic connection

Related Terms

  • long-term potentiation
  • plasticity

Examples of long-term depression in the following topics:

  • Synaptic Plasticity

    • Synaptic plasticity can be either short-term (synaptic enhancement or synaptic depression) or long-term.
    • Two processes in particular, long-term potentiation (LTP) and long-term depression (LTD), are important forms of synaptic plasticity that occur in synapses in the hippocampus: a brain region involved in storing memories .
    • Short-term synaptic depression can also arise from post-synaptic processes and from feedback activation of presynaptic receptors.
    • Long-term depression (LTD) is essentially the reverse of LTP: it is a long-term weakening of a synaptic connection.
    • Calcium entry through postsynaptic NMDA receptors can initiate two different forms of synaptic plasticity: long-term potentiation (LTP) and long-term depression (LTD).
  • Hormonal Regulation of Stress

    • The adrenal glands respond to either short-term or long-term stressors by releasing different hormones that act differently on the body.
    • Glycogen reserves, which provide energy in the short-term response to stress, are exhausted after several hours and cannot meet long-term energy needs.
    • In this situation, the body has evolved a response to counter long-term stress through the actions of the glucocorticoids, which ensure that long-term energy requirements can be met.
    • Long-term stress response differs from short-term stress response.
    • In a long-term stress response, the hypothalamus triggers the release of ACTH from the anterior pituitary gland.
  • Climate and Weather

    • Climate refers to long-term, predictable atmospheric conditions, while weather refers to atmospheric conditions during a short period of time.
    • These misconceptions often arise because of confusion over the terms climate and weather.
    • Climate refers to the long-term, predictable atmospheric conditions of a specific area .
    • You would be thinking about climate when you plan the event in the summer rather than the winter because you have long-term knowledge that any given Saturday in the months of May to August would be a better choice for an outdoor event in Wisconsin than any given Saturday in January.
    • Climate refers to long-term, predictable atmospheric conditions of a specific area.
  • Theories of Life History

    • Populations of K-selected species tend to exist close to their carrying capacity (hence the term K-selected) where intraspecific competition is high.
    • These species produce few offspring, have a long gestation period, and often give long-term care to their offspring.
    • In plants, scientists think of parental care more broadly: how long fruit takes to develop or how long it remains on the plant are determining factors in the time to the next reproductive event.
    • Animals that are r-selected do not give long-term parental care and the offspring are relatively mature and self-sufficient at birth.
    • (A) Elephants are considered K-selected species as they live long, mature late, and provide long-term parental care to few offspring.
  • Skeletal Muscle Fibers

    • Myocytes, sometimes colloquially termed “muscle fibers” form the bulk of muscle tissue.
    • The sarcoplasm is rich with glycogen and myoglobin which store the glucose and oxygen required for energy generation; and is almost completely filled with myofibrils, the long fibers composed of myofilaments that facilitate muscle contraction.
    • Myofibrils are composed of long myofilaments of actin and myosin and other associated proteins.
    • These proteins are organized into regions termed sarcomeres which are the functional contractile region of the myocyte.
    • The molecular model of contraction which describes the interaction between actin and myosin myofilaments is termed the cross bridge cycle.
  • Varying Rates of Speciation

    • In terms of how quickly speciation occurs, two patterns are currently observed: the gradual speciation model and the punctuated equilibrium model.
    • In the punctuated equilibrium model, a new species changes quickly from the parent species and then remains largely unchanged for long periods of time afterward.
    • Layers of their fossils would appear similar for a long time.
    • In (b) punctuated equilibrium, species diverge quickly and then remain unchanged for long periods of time.
  • Pre-Cambrian Animal Life

    • It is believed that early animal life, termed Ediacaran biota, evolved from protists at this time.
    • The earliest life comprising Ediacaran biota was long believed to include only tiny, sessile, soft-bodied sea creatures.
    • They are believed to show the existence of hard body parts and spicules that extended 20–40 cm from the main body (estimated about 5 cm long).
    • While the validity of this claim is still under investigation, these primitive fossils appear to be small, one-centimeter long, sponge-like creatures.
  • Introduction to Light Energy

    • This may seem illogical, but think of it in terms of a person moving a heavy rope.
    • It takes little effort by a person to move a rope in long, wide waves.
  • Glomeromycota

    • Fossil records indicate that trees and their root symbionts share a long evolutionary history.
    • This association is termed biotrophic .
    • A long-held theory is that Glomeromycota were instrumental in the colonization of land by plants.
  • Infertility

    • Short-term stress can affect hormone levels, while long-term stress can delay puberty, causing less-frequent menstrual cycles.
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