***********
Golgi cells
***********


**Overview**
   (adapted from: http://www.scholarpedia.org/article/Cerebellum#Neuronal_types):

   Golgi cells are inhibitory interneurons. There are two sizes of Golgi cells: (I)
   large ones (somata 9-16 µm in diameter), which are found mainly in the
   upper part of the granular cell layer, and (2) smaller ones (somata
   6-l l µm in diameter), which are found in the lower half of the
   granular layer. They have extensive radial dendritic trees that extend
   through all layers of the cortex. They receive input from
   the parallel fibers in the molecular layer and from climbing and mossy
   fiber collaterals in the granular layer. Their axons branch repeatedly
   in the granular layer, where they terminate on granule cell dendrites
   in the cerebellar glomeruli. There are approximately as many Golgi
   cells as Purkinje cells.
   
See :ref:`microcircuit` for a diagram of Golgi Cells.


In addition to the connections described above (input from parallel fibers and
climbing and mossy fiber collaterals) Golgi cells are also connected to each other
via gap junctions :cite:`DeZeeuwCI+2-2021` and inhibit each other by
synaptic connections :cite:`HullC+RegehrWG-2012`.
Also, some Golgi cells receive inhibition from deep Cerebellar Nuclei :cite:`AnkriL+5-2015`.

:cite:`LoebnerEE-1989` Fig 2 :ref:`about` has arrows for connections between Golgi cells and Basket cells.
But according to :cite:`DeZeeuwCI+2-2021` connections between Golgi Cells and molecular
layer interneuronshave been ruled out.  So removing these connections would be an update to the figure
to account for more recent data.

Some additional connections needed for :cite:`LoebnerEE-1989` Fig 2 are between
Golgi cells (both gap junctions and synaptic connections).


Quantity
========

Cat:

   4.2x10^5 :cite:`LoebnerEE-1989` Fig 2

   The numerical ratio of Golgi cells : Purkinje cells was 1 : 3 :cite:`PalkovitsM+2-1971b`, p. 30.
   The total number of Purkinje ceils was 1.2-1.3 million. :cite:`PalkovitsM+2-1971a`.  These two
   quantities would mean that the number of Golgi cells would be about 1.25 million / 3, or about
   4.17 x 10^5.  This is probably the source of data in LoebnerEE-1989 Fig. 2.

 
Connection to Granule Cells
===========================

Divergence
----------

Cat:

   5.2x10^3 :cite:`LoebnerEE-1989` Fig 2


Convergence
-----------

Cat: Unknown. :cite:`LoebnerEE-1989` Fig 2.



Gap junctions between Golgi Cells
=================================

Described in: :cite:`DugueGP-2009+8`.


Synaptic inhibition between Golgi Cells
=======================================


Described in:  :cite:`HullC+RegehrWG-2012`


.. tbldata:: table_loebner_fig2a
   :id_prefix: g

   Source cell | Cell count or Target cell| Value       | Reference
   golgi       | Cell count               | 4.2x10^5    | LoebnerEE-1989
   golgi       | golgi                    | ?, ?        | HullC+RegehrWG-2012
   golgi       | granule                  | 5.2x10^3, ? | LoebnerEE-1989



.. footbibliography::