Unipolar Brush Cells

Unipolar Brush cells (UBC) are excitatory interneurons located in the granular layer that acts as relay cells for glomerulus [1]. The default configuration for UBCs is implemented in ubc.yaml.

Cellular density

The density of UBC depends on the cerebellar cortex regions. Sekerková et al. (2014) [2] have reported the following densities for mouse brain:

Brain region name	Density (\(mm^{-3}\))
Lingula (I)	6000
Lobule II	6000
Central Lobule	6000
Culmen	6000
Declive (VI)	6000
Folium-tuber vermis (VII)	6000
Pyramus (VIII)	6000
Uvula (IX)	25600
Nodulus (X)	98400
Simple lobule	6000
Ansiform lobule	6000
Paramedian lobule	25600
Copula pyramidis	25600
Flocculus	78000

Remember that these values need to be converted into cell / \(\mu m^{-3}\) to be used in BSB configurations.

Connectivity

UBC are here represented with one dendrite (max. 50 \(\mu m\) long), that connects to a single glomerulus and produces 4 axons (max. 500 \(\mu m\) long), each having one UBC glomerulus terminals.

Note

UBC cells can have more than one dendrite but this subpopulation is not represented in the current circuit. It is also unclear if only a single UBC can connect to a glomerulus so this constraint is at the moment not implemented in the provided configurations.

Mf and UBC based glomeruli act similarly in the network: GrC, GoC and UBC can connect to them simultaneously. UBC are also inhibited by Golgi cells that sends axons to their presynaptic glomerulus. One third of the UBC population is reported to receive input from mf glomerulus while the rest receives input from UBC glomerulus. See review of Mugnaini et al. (2011) [1] for more information. The connection id of the first column corresponds to the numbers reported in Fig. 1 and overrides the table Connectivity rules of the cerebellar cortex circuit of the canonical circuit.

#	Source Name	Source Branch	Target Name	Target Branch	Strategy	References
2	glom & ubc_glon	/	GrC	dendrites	ConnectomeGlomerulusGranule	Houston et al. (2017) [3]
3	glom & ubc_glon	/	GoC	basal dendrites	ConnectomeGlomerulusGolgi	Kanichay and Silver (2008) [4]
16	UBC	/	ubc_glom	/	ConnectomeUBCGlomerulus	Mugnaini et al. (2011) [1]
17	glom & ubc_glon	/	UBC	/	ConnectomeGlomerulusUBC	Mugnaini et al. (2011) [1]
18	Golgi	axon	UBC	/	ConnectomeGolgiGlomerulus	Mugnaini et al. (2011) [1]

References

[1] (1,2,3,4,5)

Mugnaini, E., Sekerková, G., & Martina, M. (2011). “The unipolar brush cell: a remarkable neuron finally receiving deserved attention.” Brain research reviews, 66(1-2), 220-245. https://doi.org/10.1016/j.brainresrev.2010.10.001

[2]

Sekerková, G., Watanabe, M., Martina, M., & Mugnaini, E. (2014). “Differential distribution of phospholipase C beta isoforms and diaglycerol kinase-beta in rodents cerebella corroborates the division of unipolar brush cells into two major subtypes.” Brain Structure and Function, 219, 719-749. https://doi.org/10.1007/s00429-013-0531-9

[3]

Houston, C. M., Diamanti, E., Diamantaki, M., Kutsarova, E., Cook, A., Sultan, F., & Brickley, S. G. (2017). “Exploring the significance of morphological diversity for cerebellar granule cell excitability.” Scientific Reports, 7(1), 1-16. https://doi.org/10.1038/srep46147

[4]

Kanichay, R. T., & Silver, R. A. (2008). “Synaptic and cellular properties of the feedforward inhibitory circuit within the input layer of the cerebellar cortex.” Journal of Neuroscience, 28(36), 8955-8967. https://doi.org/10.1523/JNEUROSCI.5469-07.2008