Escape reflex, or escape behavior, is any kind of escape response found in an animal when it is presented with an unwanted stimulus. It is a simple reflectory reaction in response to stimuli indicative of danger, that initiates an escape motion of an animal. The escape response has been found to be processed in the telencephalon. Cockroach escape reflex

Escape reflexes control the seemingly chaotic motion of a cockroach running out from under a foot when one tries to squash it. Escape reflex muscles

In higher animals, examples of escape reflex include the withdrawal reflex (e.g. the withdrawal of a hand) in response to a

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

stimulus.

Sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cell ...

s in the stimulated body part send signals to the spinal cord along a sensory neuron. Within the spine, a reflex arc switches the signals straight back to the muscles of the arm ( effectors) via an intermediate neuron (

interneuron Interneurons (also called internuncial neurons, relay neurons, association neurons, connector neurons, intermediate neurons or local circuit neurons) are neurons that connect two brain regions, i.e. not direct motor neurons or sensory neurons. I ...

) and then a

motor neuron A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectl ...

; the muscle contracts. There often is an opposite response of the opposite limb. Because this occurs automatically and independently in the spinal cord, the brain only becomes aware of the response after it has taken place.

Crossed extensor reflex

The crossed extensor reflex is another escape reflex, but it's a type of withdrawal reflex. It is a contralateral reflex that allows for the affected limb to have the flexor muscles contract and the extensor muscles to relax while the unaffected limb has the flexor muscles relax and the extensor muscles to contract. For example, stepping on a piece of glass causes the affected leg to be lifted or withdrawn and the unaffected leg to carry the additional burden of weight and maintain postural support. In this example, the

afferent nerve fiber Afferent nerve fibers are the axons (nerve fibers) carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections ''arrive'' at a particular brain region. Efferent nerve fibers a ...

s are stimulated on the right foot. The nerve fibers travel up to the spinal cord where they cross the midline, go to the left side, and synapse on an interneuron. When the afferent nerve fibers synapse on the interneuron, they can either inhibit or excite an alpha motor neuron on the muscles on side contralateral to the stimulus.

Escape reflex arcs

Escape reflex arcs have a high survival value enabling organisms to take rapid action to avoid potential danger or physical damage. The effectiveness of escape reflexes can be lowered when an organism is experiencing high levels of fatigue and or stress. These factors cause delays or weakness in the reflex, and they can even develop into learned helplessness, which has been found in animals and ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many s ...

'' flies. The reflex can also be habituated as seen in the tail-flip escape reflex of crayfish. More recent studies have also indicated that, once this crayfish escape response is habituated, it can also be recovered. A similar long-term habituation of the C-start escape response has also been studied in the larvae of zebrafish. Various animals may have specialized escape reflex arcs.

Examples

*Withdrawal reflexes **Ducking (flexing the neck to protect the head) **Jumping at loud sounds **Withdrawal of a body part when it touches something (e.g., excessively hot or cold) *Other ** Lateral giant escape and tail-flip reflex in

crayfish Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, ...

** Escape reflex in squid ** Dorsal ramp interneuron (DRI) action in ''Tritonia''

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

** C-start in

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...

and amphibia **Escape reflex in

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. ...

References

{{DEFAULTSORT:Escape Reflex Reflexes Behavioral neuroscience

Crossed extensor reflex

Escape reflex arcs

Examples

See also

References