synaptic plasticity

(noun)

The ability of the connection, or synapse, between two neurons to change in strength in response to either use or disuse of transmission over synaptic pathways.

Related Terms

Examples of synaptic plasticity in the following topics:

  • Synaptic Plasticity

    • Synaptic plasticity is the strengthening or weakening of synapses over time in response to increases or decreases in their activity.
    • Synaptic plasticity is the basis of learning and memory, enabling a flexible, functioning nervous system.
    • Synaptic plasticity can be either short-term (synaptic enhancement or synaptic depression) or long-term.
    • Short-term synaptic plasticity acts on a timescale of tens of milliseconds to a few minutes.
    • Calcium entry through postsynaptic NMDA receptors can initiate two different forms of synaptic plasticity: long-term potentiation (LTP) and long-term depression (LTD).

  • Modulation of Movement by the Cerebellum

    • Several theoretical models have been developed to explain sensorimotor calibration in terms of synaptic plasticity within the cerebellum.
    • Although a full understanding of cerebellar function remains elusive, at least four principles are identified as important: 1) feedforward processing, 2) divergence and convergence, 3) modularity, and 4) plasticity.
    • Plasticity: The synapses between parallel fibers and Purkinje cells, and the synapses between mossy fibers and deep nuclear cells, are both susceptible to modification of their strength.

  • Neuroplasticity

    • However, recent findings show that many aspects of the brain remain plastic even into adulthood.
    • Plasticity can be demonstrated over the course of virtually any form of learning.
    • Pruning removes axons from synaptic connections that are not functionally appropriate.
    • Synaptic pruning is distinct from the regressive events seen during older age.
    • Synaptic pruning is like carving a statue: getting the unformed stone into its best form.

  • Synaptic Transmission

    • In a chemical synapse, the pre and post synaptic membranes are separated by a synaptic cleft, a fluid filled space.
    • The synaptic vesicles fuse with the presynaptic axon terminal membrane and empty their contents by exocytosis into the synaptic cleft.
    • As long as it is bound to a post synaptic receptor, a neurotransmitter continues to affect membrane potential.
    • Second, degradation by enzymes in the synaptic cleft such as acetylcholinesterase.
    • The calcium entry causes synaptic vesicles to fuse with the membrane and release neurotransmitter molecules into the synaptic cleft.

  • Cholinergic Neurons and Receptors

    • Acetylcholine is a neurotransmitter in the central and peripheral nervous systems that affects plasticity, arousal, and reward.
    • In the central nervous system, ACh has a variety of effects as a neuromodulator for plasticity, arousal, and reward.
    • This enzyme is abundant in the synaptic cleft, and its role in rapidly clearing free acetylcholine from the synapse is essential for proper muscle function.

  • Excitation–Contraction Coupling

    • The end of the neuron's axon is called the synaptic terminal; it does not actually contact the motor-end plate.
    • A small space called the synaptic cleft separates the synaptic terminal from the motor-end plate.
    • Neuron action potentials cause the release of neurotransmitters from the synaptic terminal into the synaptic cleft, where they can then diffuse across the synaptic cleft and bind to a receptor molecule on the motor end plate.
    • The Ca2+ ions allow synaptic vesicles to move to and bind with the presynaptic membrane (on the neuron) and release neurotransmitter from the vesicles into the synaptic cleft.
    • Once released by the synaptic terminal, ACh diffuses across the synaptic cleft to the motor end plate, where it binds with ACh receptors.

  • Neural Networks

    • In 1949, neuroscientist Donald Hebb proposed that simultaneous activation of cells leads to pronounced increase in synaptic strength between those cells, a theory that is widely accepted today.
    • Since Hebb's discovery, neuroscientists have continued to find evidence of plasticity and modification within neural networks.

  • Cognitive Development in Childhood

    • If a neuron is not being used by the brain, it goes through a process known as synaptic pruning—the removal of unnecessary neurons to make room for necessary ones.
    • Due to synaptic pruning, myelination, and a child's environmental experiences, the developing brain will grow from 30 percent of its adult weight at birth to 70 percent by age 2.
    • Also known as brain plasticity, neuroplasticity is an umbrella term that refers to changes in neural pathways and synapses caused by changes in behavior, environment, neural processes, thinking, and emotions—as well as changes resulting from bodily injury.

  • The Age of Plastics

    • Many modern adhesives involve the formation of a plastic bonding substance.
    • Plastics have replaced an increasing number of natural substances.
    • In the manufacture of piano keys and billiard balls plastics have replaced ivory, assisting the survival of the elephant.
    • With all these advantages it is not surprising that much of what you see around you is plastic.
    • Indeed, many plastics are employed in disposable products meant only for a single use.

  • The complexities of recycling

    • PET plastics are commonly used to make food and drink containers.
    • When recycled, HDPE plastics are reduced to landfill liners, fencing material, flower pots, plastic lumber, recycling bins, buckets, oil containers and benches.
    • The seventh category of plastic includes plastics that do not fall into the previous six categories.
    • One example is malamine, a plastic used to make plastic cups and plates.
    • When recycled, category-seven plastics can be used to make plastic lumber and plastic bottles.