The human brain in numbers I: neurons
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             |   &lt; 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.



References:


Herculano-Houzel, 2009
Shariff, 1953
Anderson et al, 1992
Pelvig et al, 2008
Schumann et al, 2005
West et al, 1990
Leuba et al 1994
University of Washington
Healthline.com
Wikipedia Cortical minicolumn
Wikipedia Cortical hypercolumn