Deep Cerebellar Nuclei

Overview

From: https://en.wikipedia.org/wiki/Deep_cerebellar_nuclei:

The cerebellum has four deep cerebellar nuclei embedded in the white matter in its center. These nuclei receive inhibitory (GABAergic) inputs from Purkinje cells in the cerebellar cortex and excitatory (glutamatergic) inputs from mossy fiber and climbing fiber pathways. Most output fibers of the cerebellum originate from these nuclei. One exception is that fibers from the flocculonodular lobe synapse directly on vestibular nuclei without first passing through the deep cerebellar nuclei. The vestibular nuclei in the brainstem are analogous structures to the deep nuclei, since they receive both mossy fiber and Purkinje cell inputs. From lateral to medial, the four deep cerebellar nuclei are the dentate, emboliform, globose, and fastigii. Some animals, including humans, do not have distinct emboliform and globose nuclei, instead having a single, fused interposed nucleus. In animals with distinct emboliform and globose nuclei, the term interposed nucleus is often used to refer collectively to these two nuclei.

Quantity

Cat:

The total number of the cerebellar nuclear cells was found to be 4.6x10^4. On the basis of karyometric studies the medial and interpositus nuclei appear to contain two, the lateral nucleus probably three different neuron populations. The over-all numerical ratio between Purkinje and nuclear cells is 26:1. [PalkovitsM+3-1977].

4.8x10^4, [LoebnerEE-1989] Fig 2

Excitatory connection to Granule and Golgi Cells

From [AnkriL+5-2015]:

A less-known nucleo-cortical circuit is formed by the glutamatergic neurons of the CN which, in addition to projecting to various premotor and associative regions of the brain … send axonal collaterals to the cerebellar granule cell layer (GrCL; Houck and Person, 2015). These collateral fibers form MF-like terminals contacting granule cell (GrC) and Golgi cell dendrites … . The functional significance of this excitatory nucleo-cortical (eNC) pathway, loosely following the modular arrangement of the cerebellum … is likely related to efference copying of motor commands to the cerebellar cortex (Sommer and Wurtz, 2008; Houck and Person, 2015).

Inhibitory connection to Golgi Cells

Some Golgi cells receive inhibition from deep Cerebellar Nuclei [AnkriL+5-2015]. From abstract: (data from mice):

The cerebellum, a crucial center for motor coordination, is composed of a cortex and several nuclei. The main mode of interaction between these two parts is considered to be formed by the inhibitory control of the nuclei by cortical Purkinje neurons. We now amend this view by showing that inhibitory GABA-glycinergic neurons of the cerebellar nuclei (CN) project profusely into the cerebellar cortex, where they make synaptic contacts on a GABAergic subpopulation of cerebellar Golgi cells. These spontaneously firing Golgi cells are inhibited by optogenetic activation of the inhibitory nucleo-cortical fibers both in vitro and in vivo. Our data suggest that the CN may contribute to the functional recruitment of the cerebellar cortex by decreasing Golgi cell inhibition onto granule cells.

Inhibitory connection to Inferior Olive

From [AnkriL+5-2015]:

Currently, the cerebellar cortex and the CN are known to interact through two circuits. The best known is the nucleo-olivary (NO) circuit (…) where the small GABAergic CN cells, subject to PN inhibition (Najac and Raman, 2015), project to the contralateral IO (Fredette and Mugnaini, 1991). This pathway regulates olivary activity (…) and thereby complex spike activity in the PNs and cerebellar cortical plasticity (…).

Data for table Cells and connections in cat

The following table has data and references for table Cells and connections in cat. Values are either a Cell count, or FO,FI where FO is fan-out (number of target cells each source cell contacts) and FI is fan-in (number of source cells going to each target cell).

Id	Source cell	Target cell	Value	Reference
d1	dcn	Cell count	4.6x10^4	[PalkovitsM+3-1977] 1

1

M. Palkovits, Eva Mezey, J. Hamori, and J. Szentagothai. Quantitative histological analysis of the cerebellar nuclei in the cat. I. Numerical data on cells and on synapses. Experimental Brain Research, May 1977. URL: http://link.springer.com/10.1007/BF00237096, doi:10.1007/BF00237096, Notes: PalkovitsM+3-1977.html.