The lateral giant interneuron (LG) is an interneuron

Interneuron

An interneuron is a multipolar neuron which connects afferent neurons and efferent neurons in neural pathways...

 in the abdominal nerve

Nerve

A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...

 cord of crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

. It is part of the system that controls a special kind of escape reflex

Escape reflex

Escape reflex, a kind of escape response, is a simple reflectory reaction in response to stimuli indicative of danger, that initiates an escape motion of an animal....

 of crayfish.

When the sensory hairs of the tail fan

Decapod anatomy

The decapod crustacean, such as a crab, lobster, shrimp or prawn, is made up of nineteen body segments grouped into two main body parts, the cephalothorax and the abdomen. Each segment may possess one pair of appendages, although in various groups these may be reduced or missing...

 of crayfish are stimulated, the LG activates the motor neuron

Motor neuron

In vertebrates, the term motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles...

s that control flexion movements of the abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

 in the way that propels the crayfish away from the source of the stimulation. The LG bypasses the main neural system that controls locomotion, thus shortening the reaction time.

The lateral giant connection to motor giant fast flexor neurons was the first known example of an electrical synapse

Electrical synapse

An electrical synapse is a mechanical and electrically conductive link between two abutting neurons that is formed at a narrow gap between the pre- and postsynaptic neurons known as a gap junction. At gap junctions, such cells approach within about 3.5 nm of each other, a much shorter...

(Furshpan & Potter, 1957).