Neural pathway

Neural pathway

A neural pathway, neural tract, or neural face, connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter. Neural pathways serve to connect relatively distant areas of the brain or nervous system, compared to the local communication of grey matter.

Contents

Naming of neural pathways

The first named pathways are evident to the naked eye even in a poorly-preserved brain, and were named by the great anatomists of the Renaissance using cadaver material. Examples of these include the great commissures of the brain such as the corpus callosum (Latin, "hard body"; not to be confused with the Latin word "colossus" - the "huge" statue), anterior commissure, and posterior commissure. Further examples of this (by no means a complete list) include the pyramidal tract, crus cerebri (Latin, "leg of the brain"), and cerebellar peduncles (Latin, "little foot of the cerebellum"). Note that these names describe the appearance of a structure but give one no information on its function or location.

Later, as neuroanatomical knowledge became more sophisticated, the trend was toward naming pathways by their origin and termination. For example, the nigrostriatal pathway, which is degenerated in Parkinson's disease, runs from the substantia nigra (Latin, "black substance") to the corpus striatum (Latin, "striped body"). This naming can extend to include any number of structures in a pathway, such that the cerebellorubrothalamocortical pathway originates in the cerebellum, synapses in the red nucleus ("ruber" in Latin), on to the thalamus, and finally terminating in the cerebral cortex.

Sometimes, these two naming conventions coexist. For example, the name "pyramidal tract" has been mainly supplanted by lateral corticospinal tract in most texts. Note that the "old" name was primarily descriptive, evoking the pyramids of antiquity, from the appearance of this neural pathway in the medulla oblongata. The "new" name is based primarily on its origin (in the primary motor cortex, Brodmann area 4) and termination (onto the alpha motor neurons of the spinal cord).

Functional aspects

In general, neurons receive information either at their dendrites or cell bodies. The axon of a nerve cell is, in general, responsible for transmitting information over a relatively long distance. Therefore, most neural pathways are made up of axons. If the axons have myelin sheaths, then the pathway appears bright white because myelin is primarily lipid. If most or all of the axons lack myelin sheaths (i.e., are unmyelinated), then the pathway will appear a darker beige color, which is generally called gray (American English, or grey in British English).

Some neurons are responsible for conveying information over long distances. For example, motor neurons, which travel from the spinal cord to the muscle, can have axons up to a meter in length in humans; the longest axon in the human body is almost two meters long in tall individuals and runs from the great toe to the medulla oblongata of the brainstem. These are archetypical examples of neural pathways.

Major neural pathways

Dopamine pathways:

References

  • Haines DE. Neuroanatomy: An Atlas of Structures, Sections, and Systems ISBN 0-7817-3736-2.

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Neural top down control of physiology — concerns the direct regulation by the brain of physiological functions (in addition to smooth muscle and glandular ones). Cellular functions include the immune system’s production of T lymphocytes and antibodies, and nonimmune related homeostatic …   Wikipedia

  • Neural cell adhesion molecule — 1 PDB rendering based on 1epf …   Wikipedia

  • Neural stem cell — Latin cellula nervosa precursoria Code TH H2.00.01.0.00010 Neural stem cells (NSCs) are the self renewing, multipotent cells that generate the main phenotypes of the nervous system. In 1989, Sally Temple described multipotent, self renewing… …   Wikipedia

  • Neural tube defect — Classification and external resources ICD 10 Q00, Q01, Q05 …   Wikipedia

  • Neural development — comprises the processes that generate, shape, and reshape the nervous system, from the earliest stages of embryogenesis to the final years of life. The study of neural development aims to describe the cellular basis of brain development and to… …   Wikipedia

  • Neural tube — Transverse section of half of a chick embryo of forty five hours incubation. The dorsal (back) surface of the embryo is towards the top of this page, while the ventral (front) surface is towards the bottom. (Neural tube is in green.) …   Wikipedia

  • Neural decoding — is a neuroscience related field concerned with the reconstruction of sensory and other stimuli from information that has already been encoded and represented in the brain by networks of neurons. The main goal of studying neural decoding is to… …   Wikipedia

  • Neural correlates of consciousness — The Neuronal Correlates of Consciousness (NCC) constitute the smallest set of neural events and structures sufficient for a given conscious percept or explicit memory. This case involves synchronized action potentials in neocortical pyramidal… …   Wikipedia

  • pathway — 1. A collection of axons establishing a conduction route for nerve impulses from one group of nerve cells to another group or to an effector organ composed of muscle or gland cells. 2. Any sequence of chemical reactions leading from one …   Medical dictionary

  • neural arc — a series of two or more neurons connecting certain receptors and effectors, and constituting the pathway for neural reactions and reflexes; called also sensorimotor a …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”