Righting reflex
Sensory information from the vestibular system allows the head to move back into position when disturbed as the rest of the body follows.
The semicircular canals (brown, see figure) are arranged at angles to the horizontal plane of the head when it is in its normal vertical posture.
[3] Curvature and size of these canals seems to affect agility, and may be due to the environments in which animals navigate, such as a mostly two-dimensional landscape as compared to three-dimensional spaces (i.e. in the air, the trees, or the water).
[5] Nerve fibers attached to these hair cells carry signals to the vestibular nuclei in the brain, which are then used to gain information about the body's position.
When startled, the brain can evoke anticipatory postural adjustments, or a series of muscle movements, which involves the function of the midbrain.
Data support the generation of these movements from circuits in the spine connected to the supplementary motor area, the basal ganglia, and the reticular formation.
Visual input for proper righting reflex function is perceived in the form of reference frames, which create a representation of space for comparison to expected orientation.
Three types of reference frames are used to perceive vertical orientation; they are consistently updated and quickly adapting to process changes in vestibular input.
Muscle vibrations can be used to alter a subject's perception of the location of their bodies by creating an abnormal somatosensory signal.
[8] The geocentric reference frame involves visual inputs to help detect the verticality of an environment through gravitational pull.
The sole of the foot contains receptors in the skin to detect the force of gravity, and plays a large role in standing or walking balance.
The dynamic visual acuity test involves a patient's ability to control eye movements by following letters that appear on a screen.
Nystagmus in patients indicates dysfunction of the vestibular system, which can lead to dizziness and inability to complete a righting reflex.
Recently blind patients must form new connections where visual inputs once were, and vestibular therapy may enhance this ability.
This disorder can disrupt the function of the righting reflex as the symptoms of vertigo and disorientation prevent proper postural control.
This can result from a number of factors, including head injury, ear infection, genetic predisposition, chemical toxicity, allergies, or syphilis.
These include water pills to thin out ear fluid, eating a low-salt diet, and taking anti-nausea medication.
As a cat falls, it turns its head, rotates its spine, aligns its hindquarters, and arches its back to minimize injury.
[18] The cat reaches free fall to accomplish this, which is much lower than that of humans, and they are able to hit the ground in a relaxed body form to prevent serious injury.
Their balance system, at an orientation 180 degrees opposite to that of humans, allows them to perform powerful feats of flight while hunting in the dark.
When exposed to zero-G, bats do not undergo the series of righting reflexes that most mammals do to correct orientation because they are accustomed to resting upside-down.
