climbing fiber

Definition

Target type: cellularcomponent

The axon of inferior olive neuron that projects to the cerebellar cortex, largely via the inferior cerebellar peduncle. They range in diameter from 1-3 um and are myelinated until they enter the granule cell layer. They give off collaterals to the deep cerebellar nuclei. They synapse extensively with the dendrites of Purkinje cells in the molecular layer, where each fiber branches repeatedly to climb along the Purkinje cell dendritic tree. Each Purkinje cell is innervated by only a single climbing fiber. [NIF_Subcellular:nlx_subcell_20090203]

Climbing fibers are specialized axons originating from neurons located in the inferior olive in the brainstem. They ascend to the cerebellum, where they form synapses with Purkinje cells, the primary output neurons of the cerebellar cortex. These fibers are named for their characteristic climbing pattern of innervation on the Purkinje cell dendrites. A single climbing fiber forms multiple synapses with a single Purkinje cell, wrapping around its dendrites and forming numerous varicosities, which are swellings containing neurotransmitter vesicles. Climbing fibers are responsible for transmitting information about motor commands, sensory feedback, and learning to the cerebellar cortex. They play a crucial role in motor coordination, motor learning, and the regulation of movement. The cellular components of a climbing fiber include:

* **Axon:** The main part of the climbing fiber, extending from the inferior olive neuron to the cerebellar cortex.
* **Axon terminals:** The ends of the axon, forming synapses with Purkinje cells.
* **Varicosities:** Swellings along the axon, containing neurotransmitter vesicles.
* **Synaptic vesicles:** Membrane-bound sacs containing neurotransmitters, such as glutamate.
* **Synaptic cleft:** The space between the climbing fiber terminal and the Purkinje cell dendrite, where neurotransmitters are released.
* **Mitochondria:** Organelles responsible for generating energy for the climbing fiber.
* **Microtubules:** Structures that provide support and transport materials within the axon.
* **Neurofilaments:** Intermediate filaments that contribute to the structural integrity of the axon.
* **Cytoplasm:** The fluid that fills the axon, containing various organelles and molecules.
* **Cell membrane:** The outer boundary of the climbing fiber, regulating the movement of substances in and out of the axon.
* **Myelin sheath:** A fatty covering that insulates the axon, increasing the speed of signal transmission.
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Proteins (1)

Compounds (1)