Monocular deprivation is an experimental technique used by neuroscientists to study

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

plasticity Plasticity may refer to: Science * Plasticity (physics), in engineering and physics, the propensity of a solid material to undergo permanent deformation under load * Behavioral plasticity, change in an organism's behavior in response to exposur ...

. Generally, one of an animal's eyes is sutured shut during a period of high cortical plasticity (4–5 weeks-old in mice (Gordon 1997)). This manipulation serves as an animal model for

amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...

, a permanent deficit in visual sensation not due to abnormalities in the eye (which occurs, for example, in children who grow up with

cataracts A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or double vision, halos around ligh ...

- even after cataract removal, they do not see as well as others).

Background

David Hubel and

Torsten Wiesel Torsten Nils Wiesel (born 3 June 1924) is a Swedish Neurophysiology, neurophysiologist. With David H. Hubel, he received the 1981 Nobel Prize in Physiology or Medicine, for their discoveries concerning information processing in the visual system; ...

(who won the

Nobel Prize The Nobel Prizes ( ; ; ) are awards administered by the Nobel Foundation and granted in accordance with the principle of "for the greatest benefit to humankind". The prizes were first awarded in 1901, marking the fifth anniversary of Alfred N ...

in Physiology for their elucidation of

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 od ...

properties of cells in

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 ...

) first performed the technique in felines. Kittens, although less-closely related evolutionarily to humans even than rodents, have a remarkably similar visual system to humans. They found that

ocular dominance column Ocular dominance columns are stripes of neurons in the visual cortex of certain mammals (including humans) that respond preferentially to input from one eye or the other. The columns span multiple cortical layers, and are laid out in a striped pa ...

s (the orderly clustering of V1 neurons representing visual input from one or both eyes) were dramatically disrupted when one eye was sewn shut for 2 months. In the normal feline, about 85% of cells are responsive to input to both eyes; in the monocularly-deprived animals, no cells receive input from both eyes.Wiesel, T.N. and Hubel, D.H. (1963) Single cell responses in striate cortex of kittens deprived of vision in one eye. J. Neurophysiol., 26: 1003-1017 The monocular deprivation often leads to

that is irreversible.{{Cite book, title=Neuroscience, others=Purves, Dale, date = 4 July 2018, isbn=978-1-60535-380-7, edition=Sixth, location=New York, oclc=990257568 This physiological change was paralleled by dramatic anatomical changes. The layers representing the deprived eye in the

lateral geniculate nucleus In neuroanatomy, the lateral geniculate nucleus (LGN; also called the lateral geniculate body or lateral geniculate complex) is a structure in the thalamus and a key component of the mammalian visual pathway. It is a small, ovoid, Anatomical ter ...

of the

thalamus The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...

are atrophied. In V1, ocular dominance columns representing the open eye are dramatically enlarged, at the expense of cortical surface area representing the sutured eye
Fig. 1
- Effect of monocular deprivation on ocular dominance columns. Light areas represent V1 neurons receiving input from an eye which has been injected with radioactive amino acid. Dark areas represent neurons receiving input from the other, noninjected, eye. Image A represents normal ocular dominance columns; Image B represents ocular dominance columns after monocular deprivation). These results were confirmed in the monkey. In felines, the

critical period In developmental psychology and developmental biology, a critical period is a maturational stage in the lifespan of an organism during which the nervous system is especially sensitive to certain environmental stimuli. If, for some reason, the org ...

(the period during which deprivation could cause permanent deficits) can last up to one year with the peak occurring around 4 weeks. In monkeys, the critical period peak is around 6 months. Depriving an eye, for even a few days, during this period is sufficient to cause major changes in ocular-dominance-column anatomy and physiology. However, the results of monocular deprivation in adult cats are not the same. The ocular dominance columns do not show results of being disturbed even after the adult cat has had one of its eyes shut for over a year.

References

Visual system Plasticity (physics)