Synaptic dynamics at the neuromuscular junction: mechanisms and models.
D C Van Essen1, H Gordon, J M Soha
1Biology Division, Caltech, Pasadena, California.
Journal of Neurobiology
|January 1, 1990
Summary
Neuromuscular junction development involves polyinnervation and synapse elimination. Computer models suggest multiple interacting mechanisms, not a single one, explain these complex developmental events.
Area of Science:
- Neuroscience
- Developmental Biology
- Computational Biology
Background:
- The neuromuscular junction (NMJ) undergoes significant structural changes during development.
- This includes an initial phase of polyinnervation followed by synapse elimination.
Purpose of the Study:
- To establish a conceptual framework for understanding NMJ development.
- To evaluate cellular interactions and molecular factors involved in synapse elimination and stabilization.
- To test various models using computer simulations against biological data.
Main Methods:
- Development of a conceptual framework for NMJ development.
- Generation of computer simulations to test different mechanistic models.
- Systematic evaluation of biological data against simulation outcomes.
Main Results:
- Several simple mechanisms can explain specific experimental observations in NMJ development.
- No single mechanism fully accounts for the entire range of observed phenomena.
- Interactions among multiple mechanisms are crucial for explaining developmental processes.
Conclusions:
- A combination of mechanisms, including basal lamina scaffolds, activity-regulated sprouting factors, and intrinsic neuronal growth/withdrawal tendencies, likely mediates NMJ development.
- Models integrating multiple mechanisms provide a more comprehensive explanation for synapse stabilization and elimination.
More Related Videos
Related Concept Videos
01:09Synaptic Signaling
Neurons communicate at synapses, or junctions, to excite or inhibit the activity of other neurons or target cells, such as muscles. Synapses may be chemical or electrical.
Most synapses are chemical, meaning an electrical impulse or action potential spurs the release of chemical messengers called neurotransmitters. The neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is the postsynaptic neuron.
The presynaptic neuron fires an action potential that...
Most synapses are chemical, meaning an electrical impulse or action potential spurs the release of chemical messengers called neurotransmitters. The neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is the postsynaptic neuron.
The presynaptic neuron fires an action potential that...
01:26Chemical Synapses
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:29Neuromuscular Junction And Blockade
The site of chemical communication between a motor neuron and a muscle fiber is called the neuromuscular junction (NMJ). The end of the motor neuron at the NMJ divides into a cluster of synaptic end bulbs. The cytoplasm of these bulbs consists of synaptic vesicles enclosing acetylcholine molecules, the principal neurotransmitter released at the NMJ. The region opposite the synaptic bulb that ends in the muscle fiber is called the motor end plate, which has acetylcholine receptors. Within the...
01:19The Neuromuscular Junction
The nervous system consists of complex motor neuron circuits, including upper motor neurons originating from the cerebral cortex and lower motor neurons starting in the spinal cord, coordinating both voluntary and involuntary movements. Among these, somatic motor neurons activate skeletal muscles and are classified into alpha, beta, and gamma types. Alpha neurons are vital for voluntary movement coordination, while gamma neurons adjust muscle spindle sensitivity, and the function of beta...
01:29Relaxation of Skeletal Muscles
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
01:26Chemical Synapses
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...