Fixational eye movements (also known as fixational instability, retinal jitter) are small, involuntary eye movements that occur during visual fixation. There are three categories of fixational eye movements: microsaccades, ocular drifts, and ocular microtremor. Fixational eye movements were found in a number of species, including humans, other primates, cats, rabbits, turtles, salamanders, owls, etc. Although their existence has been known since the 1950s, the role and importance of fixational eye movements is still debated. Eye movements are the voluntary or involuntary movements of the eye. ... A fixation is the point between any two saccades, during which the eyes are relatively stationary and virtually all visual input occurs. ... Microsaccades are a kind of fixational eye movement. ... Ocular microtremor (OMT) is a constant, physiological, high frequency (peak 80Hz), low amplitude (estimated circa 150-2500nm (1)) eye tremor. ... In biology, a species is one of the basic units of biodiversity. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: wise man or knowing man) in the family Hominidae (the great apes). ... Families 15, See classification A primate is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the latter category including humans. ... Binomial name Felis catus Linnaeus, 1758 Synonyms Felis lybica invalid junior synonym The cat (or domestic cat, house cat) is a small carnivorous mammal. ... Genera Pentalagus Bunolagus Nesolagus Romerolagus Brachylagus Sylvilagus Oryctolagus Poelagus Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. ... Diversity ca. ... Suborders Cryptobranchoidea Salamandroidea Sirenoidea Salamander is the common name applied to approximately 500 species of amphibians with slender bodies, short legs, and long tails. ... Families Strigidae Tytonidae Ogygoptyngidae (fossil) Palaeoglaucidae (fossil) Protostrigidae (fossil) Sophiornithidae (fossil) Synonyms Strigidae sensu Sibley & Ahlquist Owls are a group of birds of prey. ...

In the current consensus, fixational eye movements contribute to maintain visibility, by continuously stimulating neurons in the early visual areas of the brain, which mostly respond to transient stimuli. In the absence of retinal jitter (a laboratory condition called retinal stabilization), the visual percept rapidly fades out and may even completely disappear under certain conditions (low contrast, absence of sharp edges, etc.). Neurons (also called nerve cells) are the primary cells of the nervous system. ... Italic text // ahh addiing sum spiice iin hurr`` For other uses, see Brain (disambiguation). ... Transient means passing with time. ... In physiology, a stimulus is a detectable change in the internal or external environment. ... This article or section is in need of attention from an expert on the subject. ...

Experiments in neurophysiology from different laboratories have shown that fixational eye movements, particularly microsaccades, strongly modulate the activity of neurons in several visual areas of the macaque brain. This topic is currently under active investigation. Neurophysiology is a part of physiology as a science, which is concerned with the study of the nervous system. ... Microsaccades are a kind of fixational eye movement. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ... Type species Simia inuus Linnaeus, 1758 = Simia sylvanus Linnaeus, 1758 Species See text. ... Italic text // ahh addiing sum spiice iin hurr`` For other uses, see Brain (disambiguation). ...

Fixational eye movements might also participate to the neural code in the early visual system, although this hypothesis is still a very recent line of research.

See also

• Rapid eye movement
• Saccade
• Troxler's fading

Rapid eye movement (REM) is the stage of sleep during which the most vivid (though not all) dreams occur. ... A saccade is a fast movement of an eye, head, or other part of an animals body or of a device. ... Troxlers fading or Troxlers effect is a phenomenon of visual perception. ...

References

• Roger H. S. Carpenter. Movements of the Eyes, 2nd edition (Pion, London, 1988). ISBN 0-85086-109-8
• Susana Martinez-Conde, Stephen L. Macknik & David H. Hubel. The role of fixational eye movements in visual perception. Nature Reviews Neuroscience 5(3):229-240 (2004). doi:10.1038/nrn1348 [1]