mossy fibers

Examples of mossy fibers in the following topics:

• Functions of the Cerebellum in Integrating Movements

  • In the human cerebellum, information from 200 million mossy fiber inputs is expanded to 40 billion granule cells, whose parallel fiber outputs then converge onto 15 million Purkinje cells.
  • Different modules share input from mossy fibers and parallel fibers, but in other respects they appear to function independently.
  • 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.
  • In a single cerebellar module, input from as many as a billion parallel fibers converge onto a group of less than 50 deep nuclear cells, and the influence of each parallel fiber on those nuclear cells is adjustable.
  • As the illustration on the right shows, Purkinje cell dendritic trees are flattened in a way that aligns with the microzone length, and parallel fibers cross the microzones at right angles.

• Functions of the Cerebellum

  • Divergence and convergence: In the human cerebellum, information from 200 million mossy fiber inputs is expanded to 40 billion granule cells.
  • This neural divergence is followed by parallel fiber outputs that converge onto 15 million Purkinje cells.
  • Due to their longitudinal alignment, the approximately 1000 Purkinje cells belonging to a microzone may receive input via neural convergence from as many as 100 million parallel fibers.
  • Plasticity: The synapses between parallel fibers and Purkinje cells and between mossy fibers and deep nuclear cells are both susceptible to modification of their strength.
  • In a single cerebellar module, input from as many as a billion parallel fibers converge onto a group of less than 50 deep nuclear cells, and the influence of each parallel fiber on those nuclear cells is adjustable.

• Modulation of Movement by the Cerebellum

  • It receives input from thousands of parallel fibers, each individually very weak.
  • However, each cerebellar Purkinje cell also gets input from one single climbing fiber, which is so strong that a single climbing fiber action potential will reliably cause a target Purkinje cell to fire a burst of action potentials.
  • The basic concept of the Marr-Albus theory is that the climbing fiber serves as a teaching signal, which induces a long-lasting change in the strength of synchronously activated parallel fiber inputs.
  • 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.
  • The influence of each parallel fiber on nuclear cells is adjustable.

• Dietary Fiber

  • Lignin, a major dietary insoluble fiber source, may alter the fate and metabolism of soluble fibers.
  • The term "fiber" is something of a misnomer since many types of so-called dietary fiber are not actually fibrous.
  • Dietary fiber is found in plants.
  • Fiber-rich plants can be eaten directly.
  • The plum's skin is a source of insoluble fiber while soluble fiber is in the pulp.

• Characteristics of Connective Tissue

  • Connective tissue fibers provide support.
  • Three types of fibers are found in connective tissue:
  • Elastic fibers are long, thin fibers that form branching network in the extracellular matrix.
  • Reticular fibers are short, fine collagenous fibers that can branch extensively to form a delicate network.
  • Collagen fibers are the strongest and most abundant of all the connective tissue fibers.

• Overview of Motor Integration

  • When a motor unit is activated, all of its fibers contract.
  • The number of muscle fibers within each unit can vary.
  • Motor units are generally recruited in order of smallest to largest (from fewest fibers to most fibers) as contraction increases.
  • These small motor units may contain only 10 fibers per motor unit.
  • These muscles may have as many as a thousand fibers in each motor unit.

• Slow-Twitch and Fast-Twitch Muscle Fibers

  • Most muscles are made up of combinations of these fibers, although the relative number substantially varies.
  • Unlike slow-twitch fibers, fast twitch-fibers rely on anaerobic respiration (glycolysis alone) to produce two molecules of ATP per molecule of glucose.
  • As fast-twitch fibers generally do not require oxygenation, they contain fewer blood vessels and mitochondria than slow-twitch fibers and less myoglobin, resulting in a paler colour.
  • Muscles controlling eye movements contain high numbers of fast-twitch fibers (~85% fast-twitch).
  • Describe the different types of skeletal muscle fibers and their respective functions

• Classification of Nerves

  • These classifications apply to both sensory and motor fibers.
  • The A group is further subdivided into four types (A-alpha, A-beta, A-delta, and A-gamma fibers) based on the information carried by the fibers and the tissues they innervate.
  • The primary role of B fibers is to transmit autonomic information.
  • C fiber axons are grouped together into what is known as Remak bundles.
  • A-delta and C fibers both contribute to the detection of diverse painful stimuli.

• Parasympathetic (Craniosacral) Division

  • The motor root carries presynaptic parasympathetic nerve fibers (general visceral efferent fibers) that terminate in the ganglion by synapsing the postsynaptic fibers traveling to target organs.
  • The sympathetic root carries postsynaptic sympathetic fibers (general visceral efferent fibers) that traverse the ganglion without synapsing.
  • The sensory root carries general sensory fibers (general somatic afferent fibers) that also do not synapse in the ganglion.
  • Some ganglia also carry special sensory fibers (special visceral afferent) for taste sensation.
  • Pre- and post-ganglionic fibers and targets are depicted.

• Fiber

  • Fiber arts refer to the use of plant, animal, or synthetic fibers to construct practical or decorative objects, prioritizing aesthetic value over utility.
  • Fiber arts, in particular, refer to objects made with these fibers; they focus on the materials and the manual labor of the artist, and tend to prioritize aesthetic value over utility.
  • In order for the fiber to be made into cloth, it must be spun into a strand.
  • Another fiber art technique is quilting, in which layers of fabric are sewn together .
  • Recently, quilted fiber art wall hangings have become popular with art collectors.