Purkinje

Overview

Adapted from: https://en.wikipedia.org/wiki/Purkinje_cell:

Purkinje cells are some of the largest neurons in the human brain with an intricately elaborate dendritic arbor, characterized by a large number of dendritic spines. Purkinje cells are found within the Purkinje layer in the cerebellum. Purkinje cells are aligned like dominos stacked one in front of the other. Their large dendritic arbors form nearly two-dimensional layers through which parallel fibers from the deeper-layers pass. These parallel fibers make relatively weaker excitatory (glutamatergic) synapses to spines in the Purkinje cell dendrite, whereas climbing fibers originating from the inferior olivary nucleus in the medulla provide very powerful excitatory input to the proximal dendrites and cell soma. Parallel fibers pass orthogonally through the Purkinje neuron’s dendritic arbor, with up to 200,000 parallel fibers forming a Granule-cell-Purkinje-cell synapse with a single Purkinje cell. Each Purkinje cell receives approximately 500 climbing fiber synapses, all originating from a single climbing fiber. Both basket and stellate cells (found in the cerebellar molecular layer) provide inhibitory (GABAergic) input to the Purkinje cell, with basket cells synapsing on the Purkinje cell axon initial segment and stellate cells onto the dendrites.

Purkinje cells send inhibitory projections to the deep cerebellar nuclei, and constitute the sole output of all motor coordination in the cerebellar cortex.

See Microcircuit of Cerebellar cortex for a diagram of Purkinje cells.

Quantity

Cat:

The total number of Purkinje ceils was 1.2-1.3 million. [PalkovitsM+2-1971a].

The granule cell : Purkinje cell ratio was 1700-1800. [PalkovitsM+2-1971b] p. 29.

Human:

15 million (total number both hemispheres) [TomaschJ-1968].

See Table 2 in note for [LangeW-1975] for granule cell : Purkinje cell ratio for different species.

Connection to Golgi Cells

Divergence

Unknown [LoebnerEE-1989]

Convergence

Unknown [LoebnerEE-1989]

Connection to Basket Cells

Divergence

Unknown [LoebnerEE-1989]

Convergence

Unknown [LoebnerEE-1989]

Connection to Purkinje Cells

Purkinje cells have inhibitory synaptic connections to other Purkinje cells through axon collaterals [WitterL+4-2016].

Structure

In mice:

Collaterals were confined to a narrow sagittal plane but extended hundreds of micrometers within that plane. [WitterL+4-2016]

Divergence and convergence

In mice:

Connection to Granule cells

[GuoC+5-2016] shows that Purkinje cells directly inhibit granule cells. “… non-canonical feedback is region specific: it is most prominent in lobules that regulate eye movement and process vestibular information”

Divergence and convergence

Unknown

Connection to DCN

Divergence

In cat:

35 “one Purkinje axon may reach potentially 35 nuclear cells.” [PalkovitsM+3-1977]. Also, [PalkovitsM+3-1977] Fig 2 (probably from the same source).

Convergence

In cat:

Around 860 “the probable convergence of Purkinje axons upon nuclear cells can be deduced as being numerically somewhere around 860” [PalkovitsM+3-1977].

700 [LoebnerEE-1989] Fig 2.

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

p1

purkinje

Cell count

1.3x10^6

[LoebnerEE-1989] 1

p2

purkinje

granule

?,?

[GuoC+5-2016] 2

p3

purkinje

dcn

35,860

[PalkovitsM+3-1977] 3

p4

purkinje

dcn

35,700

[LoebnerEE-1989] 1

1(1,2)

EE Loebner. Intelligent network management and functional cerebellum synthesis. In Raugh MR, editor, Cerebellar Models of Associative Memory: Three papers from IEEE COMPCON SPRING ‘89, pages 14–19. Research Institute for Advanced Computer Science, NASA Ames Research Center, 1989. PDF: LoebnerEE-1989.pdf, Notes: LoebnerEE-1989.html.

2

Chong Guo, Laurens Witter, Stephanie Rudolph, Hunter L. Elliott, Katelin A. Ennis, and Wade G. Regehr. Purkinje Cells Directly Inhibit Granule Cells in Specialized Regions of the Cerebellar Cortex. Neuron, 91(6):1330–1341, September 2016. URL: https://linkinghub.elsevier.com/retrieve/pii/S0896627316305037, doi:10.1016/j.neuron.2016.08.011, Notes: GuoC+5-2016.html.

3

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.