<p>In anatomy/physiology, there are 2 major categorizations of the nervous system:</p>

<ol>
<li><strong>Central nervous system</strong> (brain + spinal cord) and <strong>peripheral nervous system</strong> (all other neural structures)</li>
<li><strong>Somatic nervous system,</strong> which controls skeletal muscles and skin, and and <strong>autonomic n. system,</strong> which controls internal organs, blood vessels and glands and is further divided to <strong>sympathetic</strong> and <strong>parasympathetic system.</strong> Both the somatic and autonomic system have <strong>motor</strong> neurons that control muscles and <strong>sensory</strong> neurons that convey sensory signals. </li>
</ol>

<p><a href="https://i.sstatic.net/90mHQ.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/90mHQ.png" alt="enter image description here"></a></p>

<p>Image source: <a href="https://en.wikipedia.org/wiki/Nervous_system" rel="nofollow noreferrer">Wikipedia</a>, creative commons license</p>

<p>Neurons can be further categorized by <a href="https://en.wikipedia.org/wiki/Neurotransmitter" rel="nofollow noreferrer">neurotransmitters</a> involved (dopamine system, acetylcholine system, etc.), and by various anatomical and functional subsystems.</p>

<p>Examples of anatomical and functional structures formed by neurons:</p>

<ul>
<li><strong>Cortical areas</strong> (functional areas of the brain cortex) (<a href="https://courses.lumenlearning.com/boundless-ap/chapter/functional-systems-of-the-cerebral-cortex/" rel="nofollow noreferrer">Lumen</a>)</li>
<li><strong>Main parts of the brain:</strong> cerebrum, cerebellum and brainstem, some of which can be further divided into hemispheres, lobes and folds</li>
<li><strong>Deep structures of the brain:</strong> thalamus, hypotalamus, hypocampus, amygdala, corpus callosum, limbic system, pituitary gland, pineal gland, and structures collectivelly called <strong>basal ganglia,</strong> which include the caudate, putamen, and globus pallidus in the cerebrum, the substantia nigra in the midbrain, and the subthalamic nucleus in the diencephalon (<a href="https://mayfieldclinic.com/pe-anatbrain.htm" rel="nofollow noreferrer">Mayfield Clinic</a>). </li>
<li><strong>Areas containing either neuron cell bodies or axons:</strong> gray matter (cell bodies) and white matter (axons) of the brain and spinal cord (<a href="http://www.indiana.edu/~p1013447/dictionary/greywhit.htm" rel="nofollow noreferrer">Indiana.edu</a>)</li>
<li><strong>Histological areas of the brain:</strong> layers and columns (<a href="https://en.wikipedia.org/wiki/Cerebral_cortex" rel="nofollow noreferrer">Wikipedia</a>)</li>
<li><strong>Nuclei</strong> of the cranial nerves (<a href="https://en.wikipedia.org/wiki/Cranial_nerve_nucleus" rel="nofollow noreferrer">Wikipedia</a>)</li>
<li><strong>Centers</strong> (cardiovascular center, reflex center for cough, vomiting, etc.) in medulla oblongata (<a href="https://en.wikipedia.org/wiki/Medulla_oblongata" rel="nofollow noreferrer">Wikipedia</a>)</li>
<li><strong>Corticospinal tracts</strong> (<a href="https://en.wikipedia.org/wiki/Corticospinal_tract" rel="nofollow noreferrer">Wikipedia</a>)</li>
<li><strong>Pathways</strong> - the term is usually used for cranial nerves: visual pathway, auditory pathway, etc.</li>
<li><strong>Ganglia</strong> - anatomical structures containing neuron body cells in the peripheral nervous system (<a href="https://en.wikipedia.org/wiki/Ganglion" rel="nofollow noreferrer">Wikipedia</a>)</li>
<li><strong>Nerve plexuses</strong> - branching networks of intersecting nerves (<a href="https://en.wikipedia.org/wiki/Nerve_plexus" rel="nofollow noreferrer">Wikipedia</a>)</li>
<li><strong>Reflex arcs</strong> (<a href="https://en.wikipedia.org/wiki/Reflex_arc" rel="nofollow noreferrer">Wikipedia</a>) </li>
</ul>

CC BY-SA 4.0
2020-01-08T17:24:41.830Z
2020-01-09T13:49:54.420Z
2020-01-09T13:49:54.420Z
Jan
<p>This is an overview question. I wonder which principles of grouping neurons into higher units are there, and which principles I have overseen.</p>

<ul>
<li><p><strong>neurotransmitter systems</strong>: all neurons that release or react on a given (class or set of) neurotransmitters</p></li>
<li><p><strong>functional systems</strong>: all neurons (and groups of neurons) that are involved in performing a given task or function</p></li>
<li><p><strong>regions</strong>: all neurons in a given 3-dimensional volume of the brain, e.g. a voxel </p></li>
<li><p><strong>nuclei</strong> etc: a group of nearby neurons which somehow belong to each other (morphologically or synaptically, possibly encapsulated by some "membrane") </p></li>
<li><p><strong>clusters</strong>: a group of neurons (nearby or not) that are strongly interconnected by synapses</p></li>
<li><p><strong>independent sets</strong>: of a <a href="https://en.wikipedia.org/wiki/Multipartite_graph" rel="nofollow noreferrer">multipartite</a> subgraph of the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136126/" rel="nofollow noreferrer">brain network</a></p></li>
<li><p>groups defined <strong>by other graph-theoretical measures</strong></p></li>
<li><p><strong>pathways</strong>: a somehow distinguished (e.g. shortest) synaptical route from neuron (group) A to neuron (group) B</p></li>
<li><p><strong>cortical layers</strong></p></li>
<li><p><strong>cortical columns</strong></p></li>
</ul>

<p>To make my question specific and not too broad, let me just ask the following:</p>

<blockquote>
  <p><strong>Which principles of grouping neurons is missing in the list above?</strong></p>
</blockquote>

<p>(There should be not so many.)</p>

<p>For each classified group of neurons some numbers will be interesting to know:</p>

<ul>
<li>How many neurons do they typically comprise?</li>
<li>How many groups of the same kind are there?</li>
<li>How strongly do they overlap?</li>
</ul>

<neuroscience><methodology><cognitive-modeling><neuroanatomy>
Principles of grouping neurons
Hans-Peter Stricker
# Principles of grouping neurons

(Asked by: username_0 on 2020-01-08)

This is an overview question. I wonder which principles of grouping neurons into higher units are there, and which principles I have overseen.

* **neurotransmitter systems**: all neurons that release or react on a given (class or set of) neurotransmitters
* **functional systems**: all neurons (and groups of neurons) that are involved in performing a given task or function
* **regions**: all neurons in a given 3-dimensional volume of the brain, e.g. a voxel
* **nuclei** etc: a group of nearby neurons which somehow belong to each other (morphologically or synaptically, possibly encapsulated by some "membrane")
* **clusters**: a group of neurons (nearby or not) that are strongly interconnected by synapses
* **independent sets**: of a [multipartite](https://en.wikipedia.org/wiki/Multipartite_graph) subgraph of the [brain network](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136126/)
* groups defined **by other graph-theoretical measures**
* **pathways**: a somehow distinguished (e.g. shortest) synaptical route from neuron (group) A to neuron (group) B
* **cortical layers**
* **cortical columns**

To make my question specific and not too broad, let me just ask the following:

> **Which principles of grouping neurons is missing in the list above?**

(There should be not so many.)

For each classified group of neurons some numbers will be interesting to know:

* How many neurons do they typically comprise?
* How many groups of the same kind are there?
* How strongly do they overlap?

**Tags:** neuroscience, methodology, cognitive-modeling, neuroanatomy


---

## 1 answers

### Answer by username_1 on 2020-01-08. Score: 1

In anatomy/physiology, there are 2 major categorizations of the nervous system:

1. **Central nervous system** (brain + spinal cord) and **peripheral nervous system** (all other neural structures)
2. **Somatic nervous system,** which controls skeletal muscles and skin, and and **autonomic n. system,** which controls internal organs, blood vessels and glands and is further divided to **sympathetic** and **parasympathetic system.** Both the somatic and autonomic system have **motor** neurons that control muscles and **sensory** neurons that convey sensory signals.

[![enter image description here](https://i.sstatic.net/90mHQ.png)](https://i.sstatic.net/90mHQ.png)

Image source: [Wikipedia](https://en.wikipedia.org/wiki/Nervous_system), creative commons license

Neurons can be further categorized by [neurotransmitters](https://en.wikipedia.org/wiki/Neurotransmitter) involved (dopamine system, acetylcholine system, etc.), and by various anatomical and functional subsystems.

Examples of anatomical and functional structures formed by neurons:

* **Cortical areas** (functional areas of the brain cortex) ([Lumen](https://courses.lumenlearning.com/boundless-ap/chapter/functional-systems-of-the-cerebral-cortex/))
* **Main parts of the brain:** cerebrum, cerebellum and brainstem, some of which can be further divided into hemispheres, lobes and folds
* **Deep structures of the brain:** thalamus, hypotalamus, hypocampus, amygdala, corpus callosum, limbic system, pituitary gland, pineal gland, and structures collectivelly called **basal ganglia,** which include the caudate, putamen, and globus pallidus in the cerebrum, the substantia nigra in the midbrain, and the subthalamic nucleus in the diencephalon ([Mayfield Clinic](https://mayfieldclinic.com/pe-anatbrain.htm)).
* **Areas containing either neuron cell bodies or axons:** gray matter (cell bodies) and white matter (axons) of the brain and spinal cord ([Indiana.edu](http://www.indiana.edu/~p1013447/dictionary/greywhit.htm))
* **Histological areas of the brain:** layers and columns ([Wikipedia](https://en.wikipedia.org/wiki/Cerebral_cortex))
* **Nuclei** of the cranial nerves ([Wikipedia](https://en.wikipedia.org/wiki/Cranial_nerve_nucleus))
* **Centers** (cardiovascular center, reflex center for cough, vomiting, etc.) in medulla oblongata ([Wikipedia](https://en.wikipedia.org/wiki/Medulla_oblongata))
* **Corticospinal tracts** ([Wikipedia](https://en.wikipedia.org/wiki/Corticospinal_tract))
* **Pathways** - the term is usually used for cranial nerves: visual pathway, auditory pathway, etc.
* **Ganglia** - anatomical structures containing neuron body cells in the peripheral nervous system ([Wikipedia](https://en.wikipedia.org/wiki/Ganglion))
* **Nerve plexuses** - branching networks of intersecting nerves ([Wikipedia](https://en.wikipedia.org/wiki/Nerve_plexus))
* **Reflex arcs** ([Wikipedia](https://en.wikipedia.org/wiki/Reflex_arc))


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