neural divergence

Examples of neural divergence in the following topics:

• Functions of the Cerebellum

  • Although a full understanding of cerebellar function has remained elusive, at least four principles have been identified as important: feedforward processing, divergence and convergence, modularity, and plasticity.
  • This feedforward mode of operation means that the cerebellum, in contrast to the cerebral cortex, cannot generate self-sustaining patterns of neural activity.
  • 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.

• Modulation of Movement by the Cerebellum

  • This feedforward mode of operation means that the cerebellum cannot generate self-sustaining patterns of neural activity, in contrast to the cerebral cortex.
  • This complex neural network gives rise to a massive signal-processing capability, but almost all of its output is directed to a set of small, deep cerebellar nuclei lying in the interior of 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.
  • This means that the cerebellum, in contrast to the cerebral cortex, cannot generate self-sustaining patterns of neural activity.
  • Divergence and convergence: The 1000 or so Purkinje cells belonging to a microzone may receive input from as many as 100 million parallel fibers, and focus their own output down to a group of less than 50 deep nuclear cells.

• Development of the Peripheral Nervous System

  • The peripheral nervous system develops from two strips of tissue called the neural crest, running lengthwise above the neural tube.
  • At this point the future CNS appears as a cylindrical structure called the neural tube, whereas the future PNS appears as two strips of tissue called the neural crest, running lengthwise above the neural tube.
  • The sequence of stages from neural plate to neural tube and neural crest is known as neurulation .
  • After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm.
  • During neurulation, the borders of the neural plate, also known as the neural folds, converge at the dorsal midline to form the neural tube.

• Embryonic Development

  • The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a closed tube, the neural tube or neural canal, the ectodermal wall of which forms the rudiment of the nervous system.
  • Primary neurulation begins after the neural plate has formed.
  • The edges of the neural plate start to thicken and lift upward, forming the neural folds.
  • The center of the neural plate remains grounded allowing a U-shaped neural groove to form.
  • The neural folds pinch in towards the midline of the embryo and fuse together to form the neural tube.

• Neurulation

  • Neurulation is the formation of the neural tube from the ectoderm of the embryo.
  • The neural plate folds outwards to form the neural groove.
  • Beginning in the future neck region, the neural folds of this groove close to create the neural tube (this form of neurulation is called primary neurulation).
  • The hollow interior is called the neural canal.
  • Transverse sections that show the progression of the neural plate to the neural groove from bottom to top.

• Establishing Body Axes during Development

  • The edges of the neural plate start to thicken and lift upward, forming the neural folds.
  • The center of the neural plate remains grounded, allowing a U-shaped neural groove to form.
  • In the head, neural crest cells migrate, the neural tube closes, and the overlying ectoderm closes.
  • In the trunk, overlying ectoderm closes, the neural tube closes and neural crest cells migrate.
  • (Neural tube is in green. )

• The Divergence Theorem

  • More precisely, the divergence theorem states that the outward flux of a vector field through a closed surface is equal to the volume integral of the divergence over the region inside the surface.
  • In physics and engineering, the divergence theorem is usually applied in three dimensions.
  • We will apply the divergence theorem for a sphere of radius $R$, whose center is also at the origin.
  • Substituting $E$ for $F$ in the relationship of the divergence theorem, the left hand side (LHS) becomes:
  • Apply the divergence theorem to evaluate the outward flux of a vector field through a closed surface

• Development of Vision

  • The eye forms from the neural tube, epidermis, and the periocular mesenchyme, with sequential inductions of tissue during development.
  • The eye develops from the neural tube, the epidermis, and the periocular mesenchyme, which receives contributions from both the neural crest and mesoderm lineages.
  • Neural tube: First, there is an outpocketing of the neural tube called optic vesicles .
  • The optic cup then delaminates into two layers: the neural retina and the retinal pigment epithelium.
  • The eyes make their appearance before the closure of the anterior end of the neural tube.

• Neural Networks

  • Neural networks consist of a series of interconnected neurons, and serve as the interface for neurons to communicate with each other.
  • A neural network (or neural pathway) is the interface through which neurons communicate with one another.
  • However, we do know that we have neural networks to thank for much of our higher cognitive functioning.
  • A neural network (or neural pathway) is the complex interface through which neurons communicate with one another.
  • Explain the different theories of how neural networks operate in the body

• Embryonic Development of the Brain

  • Neural activity and sensory experience will mediate formation of new synapses, as well as synaptic plasticity, which will be responsible for refinement of the nascent neural circuits.
  • Neurulation is the formation of the neural tube from the ectoderm of the embryo.
  • The neural plate folds outwards to form the neural groove.
  • Beginning in the future neck region, the neural folds of this groove close to create the neural tube (this form of neurulation is called primary neurulation).
  • The hollow interior is called the neural canal.