Neuromorphology
Encyclopedia
Neuromorphology is the study of nervous system
form, shape, and structure. The study of its structure includes looking at the organ system from a physiological
and anatomical
point of view, as well as on a molecular and cellular level. The field also explores the communications and interactions within and between each specialized section of the nervous system.
It is important to note the difference between morphology
and morphogenesis
, so that the meaning of neuromorphology is not confused. Morphology deals with study of the shape and structure of biological organisms, while morphogenesis studies the biological development of the shape and structure of organisms. Therefore, neuromorphology focuses on the specifics of the structure and not the process by which the structure was developed.
as the basic unit of life before researchers could agree upon the shape of a neuron
. It was originally thought to be an independent globular corpuscle
suspended along nerve fibers that looped and coiled. It was not until the first successful microdissection
of a whole nerve cell by Deiters in 1865 that the separate dendrite
s and axon
could be distinguished. At the end of the 19th century, new techniques, such as Golgi's method
, were developed that enabled researchers to view the whole neuron. This Golgi investigation then promoted new research in neuronal spacing by Ramon y Cajal in 1911. Further morphology research continued to develop, including dendritic morphology.
l ganglion cell
s has been studied to show the relationship between neuron shape and function.
is dependent upon genes and other factors, such as electric fields, ionic waves, and gravity. Developing cells additionally impose geometrical and physical constraints upon each other. These interactions effect the neural shape and synaptogenesis
.
properties of neurons. Neurons can be found in different shapes and sizes and can be classified based upon their morphology. The Italian scientist Camillo Golgi
grouped neurons into type I and type II cells. Golgi I
neurons have long axons that can move signals over long distances, such as in Purkinje cells, whereas Golgi II
neurons generally have shorter axons, such as granule cell
s or are anoxonic.
Neurons can be morphologically characterizes as unipolar
, bipolar, or multipolar
. Unipolar and pseudounipolar cells have only one process
extending from the cell body. Bipolar cells have a two processes extending from the cell body and multipolar cells have three or more processes extending towards and away from the cell body.
, peripheral
, and autonomic nervous system
s. This subfield aims to expand the current understanding of the adaptive capabilities of nervous systems, and specifically examines how environmental effects can alter nervous system structure and function. Environmental manipulations generally include exposing neurons to either hypergravity
or microgravity. It is a subset of gravitational biology
.
, design-based stereology
, neuron tracing and neuron reconstruction. Current innovations and future research include virtual microscopy
, automated stereology, cortical map
ping, map guided automated neuron tracing
and network analysis. Of the currently used techniques for studying neuromorphology, design-based stereology and confocal microscopy are the two most preferred methods. A complete database of neuronal morphology called the NeuroMorpho Database also exists.
and decreased signal-to-noise ratio
. The specific way this microscopy works allows one to look at one confocal plane at a time, which is optimal when viewing neuronal structures. Other more conventional forms of microscopy simply do not allow one to visualize all neuronal structures, especially those that are subcellular. Recently, some researchers have actually been combining design-based stereology and confocal microscopy to further their investigations into the specific neuronal cellular structures.
fading during imaging. This method would additionally give researchers abilities to visualize currently unobtainable data, such as rare cell types and the spatial allocation of cells in a specific brain region. Virtual microscopy would essentially allow for the digitization
of all images obtained, therefore preventing deterioration
of the data. This digitization could also potentially permit researchers to create a database
to share and store their data.
s. More sophisticated cortical mapping techniques are still in the process of being developed and this field will most likely see an exponential growth in mapping methods in the near future.
s, and has been included in the clinical study of various neurodegenerative
diseases, mental disorders, learning disabilities
, and dysfunctions due to brain damage.
Neuromophology has been used to study optical nerve damage, specifically looking at lesion
s and atrophies
. Researchers have been using neuromorphological techniques to not only study the damage but also ways to regenerate the damage nerve through ways like axon growth stimulation.
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
form, shape, and structure. The study of its structure includes looking at the organ system from a physiological
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
and anatomical
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
point of view, as well as on a molecular and cellular level. The field also explores the communications and interactions within and between each specialized section of the nervous system.
It is important to note the difference between morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and morphogenesis
Morphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...
, so that the meaning of neuromorphology is not confused. Morphology deals with study of the shape and structure of biological organisms, while morphogenesis studies the biological development of the shape and structure of organisms. Therefore, neuromorphology focuses on the specifics of the structure and not the process by which the structure was developed.
History
Progress in defining the morphology of nerve cells has been slow in its development. It took nearly a century after the acceptance of the cellCell
-Science and technology:*Cell , the functional basic unit of life*Cell , a term used in an electronic circuit design schematics*Cell , a three-dimensional element, part of a higher-dimensional object*Cell , a scientific journal...
as the basic unit of life before researchers could agree upon the shape of a neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
. It was originally thought to be an independent globular corpuscle
Corpuscle
Corpuscle may refer to:*a small free floating biological cell, especially a blood cell, but not a fat cell*a nerve ending such as Meissner's corpuscle or a Pacinian corpuscle*any member of Corpus Christi College, Cambridge or Corpus Christi College, Oxford...
suspended along nerve fibers that looped and coiled. It was not until the first successful microdissection
Microdissection
Microdissection refers to a variety of techniques where a microscope is used to assist in dissection.Different kinds of techniques involve microdissection:...
of a whole nerve cell by Deiters in 1865 that the separate dendrite
Dendrite
Dendrites are the branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project...
s and axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
could be distinguished. At the end of the 19th century, new techniques, such as Golgi's method
Golgi's method
Golgi's method is a nervous tissue staining technique discovered by Italian physician and scientist Camillo Golgi in 1873. It was initially named the black reaction by Golgi, but it became better known as the Golgi stain or later, Golgi method.Golgi' staining was famously used by Spanish...
, were developed that enabled researchers to view the whole neuron. This Golgi investigation then promoted new research in neuronal spacing by Ramon y Cajal in 1911. Further morphology research continued to develop, including dendritic morphology.
Influence on Neuron Function
Research has supported a relationship between the morphological and functional properties of neurons. For instance, the accordance between the morphology and the functional classes of cat retinaRetina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
l ganglion cell
Ganglion cell
A retinal ganglion cell is a type of neuron located near the inner surface of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and amacrine cells...
s has been studied to show the relationship between neuron shape and function.
Development
The development of the morphological features of neurons is governed by both intrinsic and extrinsic factors. The neuromorphology of nervous tissueNervous tissue
Nervous tissue is one of four major classes of vertebrate tissue.Nervous tissue is the main component of the nervous system - the brain, spinal cord, and nerves-which regulates and controls body functions...
is dependent upon genes and other factors, such as electric fields, ionic waves, and gravity. Developing cells additionally impose geometrical and physical constraints upon each other. These interactions effect the neural shape and synaptogenesis
Synaptogenesis
Synaptogenesis is the formation of synapses. Although it occurs throughout a healthy person's lifespan, an explosion of synapse formation occurs during early brain development...
.
General Morphology
Because of the broad range of functions performed by different types of neurons in diverse parts of the nervous system, there is a wide variety in the size, shape, and electrochemicalElectrochemistry
Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor , and which involve electron transfer between the electrode and the electrolyte or species in solution.If a chemical reaction is...
properties of neurons. Neurons can be found in different shapes and sizes and can be classified based upon their morphology. The Italian scientist Camillo Golgi
Camillo Golgi
Camillo Golgi was an Italian physician, pathologist, scientist, and Nobel laureate.-Biography:Camillo Golgi was born in the village of Corteno, Lombardy, then part of the Austrian Empire. The village is now named Corteno Golgi in his honour. His father was a physician and district medical officer...
grouped neurons into type I and type II cells. Golgi I
Golgi I
A Golgi I or Golgi type I neuron is a neuron which has a long axon that begins in the grey matter of the central nervous system and may extend from there. Golgi II neurons, in contrast, are defined as having short axons or no axon at all...
neurons have long axons that can move signals over long distances, such as in Purkinje cells, whereas Golgi II
Golgi II
A Golgi II or Golgi type II neuron is a neuron having either no axon or else a short axon that does not send branches out of the gray matter of the central nervous system.-External links:* via the Neuroscience Information Framework...
neurons generally have shorter axons, such as granule cell
Granule cell
In neuroscience, granule cells refer to tiny neurons that are around 10 micrometres in diameter. Granule cells are found within the granular layer of the cerebellum , the dentate gyrus of the...
s or are anoxonic.
Neurons can be morphologically characterizes as unipolar
Unipolar neuron
A unipolar neuron is a type of neuron in which only one protoplasmic process extends from the cell body. Most neurons are multipolar, generating several dendrites and an axon...
, bipolar, or multipolar
Multipolar neuron
A multipolar neuron is a type of nig that possesses a single axon and many dendrites, allowing for the integration of a great deal of information from other neurons. These dendritic branches can also emerge from the nerve cell body...
. Unipolar and pseudounipolar cells have only one process
Process (anatomy)
In anatomy, a process is a projection or outgrowth of tissue from a larger body. The vertebra has several kinds of processes,such as: transverse process, prezygapophysis, postzygapophysis.-Examples:Examples of processes include:...
extending from the cell body. Bipolar cells have a two processes extending from the cell body and multipolar cells have three or more processes extending towards and away from the cell body.
Theoretical Neuromorphology
Theoretical neuromorphology is a branch of neuromorphology focused on the mathematical description of the shape, structure and connectivity of the nervous system.Gravitation Neuromorphology
Gravitational neuromorphology studies the effects of altered gravity on the development of the centralCentral nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, peripheral
Peripheral nervous system
The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...
, and autonomic nervous system
Autonomic nervous system
The autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...
s. This subfield aims to expand the current understanding of the adaptive capabilities of nervous systems, and specifically examines how environmental effects can alter nervous system structure and function. Environmental manipulations generally include exposing neurons to either hypergravity
Hypergravity
Hypergravity is defined as the condition where the force of gravity exceeds that on the surface of the earth. This is expressed as being greater than 1 g...
or microgravity. It is a subset of gravitational biology
Gravitational biology
Gravitational biology is the study of the effects gravity has on living organisms. Throughout the history of the Earth life has evolved to survive changing conditions, such as changes in the climate and habitat. The only constant factor in evolution since life first began on Earth is the force of...
.
Research Methods and Techniques
A variety of techniques have been used to study neuromorphology, including confocal microscopyConfocal microscopy
Confocal microscopy is an optical imaging technique used to increase optical resolution and contrast of a micrograph by using point illumination and a spatial pinhole to eliminate out-of-focus light in specimens that are thicker than the focal plane. It enables the reconstruction of...
, design-based stereology
Stereology
Stereology was originally defined as "the spatial interpretation of sections". It is an interdisciplinary field that is largely concerned with the three-dimensional interpretation of planar sections of materials or tissues...
, neuron tracing and neuron reconstruction. Current innovations and future research include virtual microscopy
Virtual microscopy
Virtual microscopy is a method of posting microscope images on, and transmitting them over, computer networks. This allows independent viewing of images by large numbers of people in diverse locations. It involves a synthesis of microscopy technologies and digita l technologies...
, automated stereology, cortical map
Cortical map
Cortical maps are collections of minicolumns in the brain cortex that have been identified as performing a specific information processing function ....
ping, map guided automated neuron tracing
Anterograde tracing
In neuroscience, anterograde tracing is a research method which is used to trace axonal projections from their source In neuroscience, anterograde tracing is a research method which is used to trace axonal projections from their source In neuroscience, anterograde tracing is a research method which...
and network analysis. Of the currently used techniques for studying neuromorphology, design-based stereology and confocal microscopy are the two most preferred methods. A complete database of neuronal morphology called the NeuroMorpho Database also exists.
Design-based Stereology
Design-based stereology is one of the most prominent methods for mathematically extrapolating a 3-D from a given 2-D form. It is currently the leading technique in biomedical research for analyzing 3-D structures.Confocal Microscopy
Confocal microscopy is the microscopic procedure of choice for examining neuron structures as it produces sharp images with improved resolutionDisplay resolution
The display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube , flat panel or projection...
and decreased signal-to-noise ratio
Signal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...
. The specific way this microscopy works allows one to look at one confocal plane at a time, which is optimal when viewing neuronal structures. Other more conventional forms of microscopy simply do not allow one to visualize all neuronal structures, especially those that are subcellular. Recently, some researchers have actually been combining design-based stereology and confocal microscopy to further their investigations into the specific neuronal cellular structures.
Virtual Microscopy
Virtual microscopy would allow researchers to obtain images with a decreased amount of imaging sessions, thus preserving the integrity of the tissue and decrease the possibility the fluorescent dyesFluorescent labelling
Fluorescent labelling is the process of covalently attaching a fluorophore to another molecule, such as a protein or nucleic acid. This is generally accomplished using a reactive derivative of the fluorophore that selectively binds to a functional group contained in the target molecule...
fading during imaging. This method would additionally give researchers abilities to visualize currently unobtainable data, such as rare cell types and the spatial allocation of cells in a specific brain region. Virtual microscopy would essentially allow for the digitization
Digitizing
Digitizing or digitization is the representation of an object, image, sound, document or a signal by a discrete set of its points or samples. The result is called digital representation or, more specifically, a digital image, for the object, and digital form, for the signal...
of all images obtained, therefore preventing deterioration
Degeneration
The idea of degeneration had significant influence on science, art and politics from the 1850s to the 1950s. The social theory developed consequently from Charles Darwin's Theory of Evolution...
of the data. This digitization could also potentially permit researchers to create a database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
to share and store their data.
Cortical Mapping
Cortical mapping is defined as the process of characterizing specific regions in the brain based on either anatomical or functional features. Current brain atlases are not definitive or homogenous enough to portray specific structural details. Recent advances in functional brain imaging and statistical analysis may however prove to be sufficient in the future. A recent development in this field called the Grey Level Index method allows for more objective identification of cortical regions via algorithmAlgorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
s. More sophisticated cortical mapping techniques are still in the process of being developed and this field will most likely see an exponential growth in mapping methods in the near future.
Clinical Applications
Neuromorphology has been used as a new method of exploring the underlying cause of many neurological disorderNeurological disorder
A neurological disorder is a disorder of the body's nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord, or in the nerves leading to or from them, can result in symptoms such as paralysis, muscle weakness, poor coordination, loss of sensation, seizures,...
s, and has been included in the clinical study of various neurodegenerative
Neurodegeneration
Neurodegeneration is the umbrella term for the progressive loss of structure or function of neurons, including death of neurons. Many neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s occur as a result of neurodegenerative processes. As research progresses, many...
diseases, mental disorders, learning disabilities
Learning disability
Learning disability is a classification including several disorders in which a person has difficulty learning in a typical manner, usually caused by an unknown factor or factors...
, and dysfunctions due to brain damage.
Neuromophology has been used to study optical nerve damage, specifically looking at lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s and atrophies
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
. Researchers have been using neuromorphological techniques to not only study the damage but also ways to regenerate the damage nerve through ways like axon growth stimulation.
Computational Neuromorphology
Computational neuromorophology examines neurons and their substructures by cutting them into slices and studying these different subsections. It also describes the neuromorphological space as a 3-D space. This allows researchers to understand the size of specific neuronal components. Additionally, the 3-D imaging helps researchers comprehend how the neuron transmits information within itself.See also
- Cellular NeuroscienceCellular neuroscienceCellular neuroscience is the study of neurons at a cellular level. This includes morphology and physiological properties of single neurons. Several techniques such as intracellular recording, patch-clamp, and voltage-clamp technique, pharmacology, confocal imaging, molecular biology, two photon...
- Morphology (Biology)Morphology (biology)In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
- Theoretical NeuromorphologyTheoretical neuromorphologyTheoretical neuromorphology is the science of using morphology to mathematically describe the shape and the connectivity in the nervous system.-History:The rational study of shapes as been long to form...