A cortical minicolumn is a vertical column through the

cortical layers The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of a ...

of the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

Neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...

s within the microcolumn "receive common inputs, have common outputs, are interconnected, and may well constitute a fundamental computational unit of the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consistin ...

". Minicolumns comprise perhaps 80–120 neurons, except in the

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter including ...

primary visual cortex The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...

(V1), where there are typically more than twice the number. There are about 2×10⁸ minicolumns in humans. From calculations, the diameter of a minicolumn is about 28–40 μm. Minicolumns grow from

progenitor cell A progenitor cell is a biological cell that can differentiate into a specific cell type. Stem cells and progenitor cells have this ability in common. However, stem cells are less specified than progenitor cells. Progenitor cells can only differ ...

s within the embryo and contain neurons within multiple layers (2–6) of the cortex. Bennet2020Figure2CorticalColumn

Many sources support the existence of minicolumns, especially Mountcastle, with strong evidence reviewed by Buxhoeveden and Casanova who conclude "... the minicolumn must be considered a strong model for cortical organization" and " he minicolumn is/nowiki> the most basic and consistent template by which the neocortex organizes its neurones, pathways, and intrinsic circuits". Cortical minicolumns can also be called cortical microcolumns. Cells in 50 μm minicolumn all have the same

receptive field The receptive field, or sensory space, is a delimited medium where some physiological stimuli can evoke a sensory neuronal response in specific organisms. Complexity of the receptive field ranges from the unidimensional chemical structure of o ...

; adjacent minicolumns may have different fields.

Number of neurons

Estimates of number of neurons in a minicolumn range from 80–100 neurons.Sporns O, Tononi G, Kötter R
The human connectome: A structural description of the human brain
PLoS Comput. Biol. 2005 Sep1(4):e42. Jones describes a variety of observations that may be interpreted as mini- or micro-columns and gives example numbers from 11 to 142 neurons per minicolumn.

Number of minicolumns

Estimates of the number of neurons in cortex or in neocortex are on the order of 2×10¹⁰. MostClaudia Krebs MD PhD, Joanne Weinberg PhD, Elizabeth Akesson MSc
Lippincott’s Illustrated Reviews: Neuroscience
accessed Nov 10 2013. Chapter 13, II.A, "Histological organization of the cortex" (perhaps 90%) of cortical neurons are neocortical neurons. Johansson and Lansner use an estimate of 2×10¹⁰ neurons in the neocortex and an estimate of 100 neurons per minicolumn, yielding an estimate of 2×10⁸ minicolumns. Sporns et al. give an estimate of 2×10⁷ – 2×10⁸ minicolumns.Sporns O, Tononi G, Kötter R
The human connectome: A structural description of the human brain
PLoS Comput. Biol. 2005 Sep1(4):e42

Size of minicolumns

The minicolumn measures of the order of 40–50 μm in transverse diameter; 35–60 μm; 50 μm with 80 μm spacing, or 30 μm with 50 μm. Larger sizes may not be of human minicolumns, for example macaque monkey V1 minicolumns are 31 μm diameter, with 142 pyramidal cells — 1270 columns per mm². Similarly, the cat V1 has much bigger minicolumns, ~56 μm. The size can also be calculated from area considerations. If cortex (both hemispheres) is 1.27×10¹¹ μm² then if there are 2×10⁸ minicolumns in the neocortex then each is 635 μm², giving a diameter of 28 μm (if the cortex area were doubled to the commonly quoted value, this would rise to 40 μm). Johansson and Lansner do a similar calculation and arrive at 36 μm (p51, last para). Downwards projecting

axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action p ...

s in minicolumns are ≈10 μm in diameter, periodicity and density similar to those within the cortex, but not necessarily coincident.

References

External links

* {{DEFAULTSORT:Cortical Minicolumn Cerebrum

Number of neurons

Number of minicolumns

Size of minicolumns

See also

References

External links