Kindling

Kindling is a widely used model for the development of seizures and epilepsy in which the duration and behavioral involvement of induced seizures increases after seizures are induced repeatedly. It is used by scientists to study the effects of repeated seizures on the brain. A seizure may increase the likelihood that more seizures will occur; an old saying in epilepsy research is "seizures beget seizures". Repeated stimulation "lowers the threshold" for more seizures to occur. In the kindling model, seizures begin to occur spontaneously after repeated subconvulsive stimuli.

The brains of experimental animals are repeatedly stimulated, usually with electricity, to induce the seizures. Chemicals may also be used to induce seizures. The seizure that occurs after the first such electrical stimulation lasts a short time and is accompanied by a small amount of behavioral effects compared with seizures that result from repeated stimulations. With further seizures, the accompanying behavior intensifies, for example progressing from freezing in early stimulations to convulsions in later ones. The lengthening of duration and intensification of behavioral accompaniment eventually reaches a plateau after repeated stimulation. Even if animals are left unstimulated for as long as 12 weeks, the effect remains; the response to stimulation remains higher than it had been before.

It has been reported that repeated seizure stimulation can result in spontaneous seizures, but studies have had conflicting findings on this question. In humans, some seizure disorders come to an end by themselves even after large numbers of seizures. However, in both human epilepsy and in some animal models, evidence suggests that a process like that found in kindling does occur.

The kindling model was first proposed in the late 1960s by Goddard and colleagues. Although kindling is widely a widely used model, its applicability to human epilepsy is controversial.

The word kindling is a metaphor: the increase in response to small stimuli is similar to the way small burning twigs can produce a large fire.