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Even though knowing the number of neurons in a functional unit or with the same function is not of main importance, it may be interesting to know their orders of magnitude, especially in the human brain. For example:

|------------------|------------------|
| cerebellum       | 100,000,000,000  |    
| cortex           |  20,000,000,000  |    
| telencephalon    |  10,000,000,000  |    
| brainstem        |   1,000,000,000  |    
| sensory neurons  |                  |     
|          haptic  |     500,000,000  |     
|          visual  |     100,000,000  |
|        auditory  |           2,000  |
| limbic system    |                  |    
|         amygdala |      10,000,000  |   
|------------------|------------------|  

Surely, for many parts of brain you will find a reference where the number of its neurons is estimated (e.g. for the amygdala) - when you search hard enough. I also found The Human Brain in Numbers where some numbers are given. But I am looking for a reference where many of these numbers are given in a systematic way, ideally in a table like the one above. Is there any?

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First of all, let me clear out that these numbers are calculated, not observed (obviously, nobody has counted the number of neurons in any part of brain). So, take these with a grain of salt.

I was unable to find any report that collects and displays all numbers together (Bio Numbers too didn't yield significant information). So I will compile here all the numbers I have found so far (and keep adding as I find more):

|----------------------|------------------|------------------------|
|PART OF BRAIN         |NUMBER OF NEURONS |               REFERENCE|
|----------------------|------------------|------------------------|
|The human brain       | over 120 billion |  Herculano-Houzel, 2009| 
|Telencephalon         |  12-15 billion   |           Shariff, 1953|
|Cerebellum            |   101 billion    |    Anderson et al, 1992|
|Cerebral cortex       |  21-26 billion   |      Pelvig et al, 2008|
|Amygdaloid complex    |    12 million    |    Schumann et al, 2005|
|Hippocampus (CA1)     |  11-24 million   |        West et al, 1990|
|Brainstem             |   < 1 billion    |  Herculano-Houzel, 2009|
|Visual cortex         |   140 million    |       Leuba et al, 1994|
|Auditory cortex       |    1 billion     |University of Washington|
|Corpus callosum       |   200 million    |          Healthline.com|
|Spinal cord           |    1 billion     |University of Washington|
|Cortical minicolumn   |      80-120      |               Wikipedia|
|Cortical hypercolumn  |   5,000-10,000   |               Wikipedia|
|----------------------|------------------|------------------------|

I will continue adding more numbers as I find them. Again, nobody will claim these numbers to be exact, these are just estimates from calculations. Even different sources show different numbers. For example, the Washington University page puts the number of neurons in visual cortex to 528 million. Thus, don't expect these numbers to be anywhere near exact.

human brain

References:

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    $\begingroup$ Just great! More than I did expect. $\endgroup$ – Hans-Peter Stricker Jul 13 '17 at 0:13
  • $\begingroup$ It would be great if the table was hierarchically organised (where possible): top level: the human brain. Way down: the amygdala,... $\endgroup$ – Hans-Peter Stricker Jul 18 '17 at 7:21
  • $\begingroup$ @hansstricker again, I don't get you. How are you categorizing them to get a hierarchy? From front to back? Number of neurons? $\endgroup$ – another 'Homo sapien' Jul 18 '17 at 9:24
  • $\begingroup$ I mean hierarchized by being-part-of. Doesn't this make sense, at least sometimes? I mean, some parts of the brain are immediate parts of the brain (cerebrum, brainstem, cerebellum), others are parts of parts, and so on. $\endgroup$ – Hans-Peter Stricker Jul 18 '17 at 11:34
  • $\begingroup$ May I add the numbers for cortical minicolumns (ca. 100) and cortical hypercolumns (ca. 100 x 100) in your table? $\endgroup$ – Hans-Peter Stricker Aug 3 '17 at 6:45

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