Friday, August 18, 2017

Gotham Snow Globe

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.[3] It is used by scientists to study the effects of repeated seizures on the brain.[1] A seizure may increase the likelihood that more seizures will occur; an old saying in epilepsy research is "seizures beget seizures".[1] Repeated stimulation "lowers the threshold" for more seizures to occur.[4]
The brains of experimental animals are repeatedly stimulated, usually with electricity, to induce the seizures.[1] Chemicals may also be used to induce seizures.[3] 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.[1] With further seizures, the accompanying behavior intensifies, for example progressing from freezing in early stimulations to convulsions in later ones.[5] The lengthening of duration and intensification of behavioral accompaniment eventually reaches a plateau after repeated stimulation.[1] 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.[3]
It has been reported that repeated seizure stimulation can result in spontaneous seizures, but studies have had conflicting findings on this question.[1] In humans, some seizure disorders come to an end by themselves even after large numbers of seizures.[1] However, in both human epilepsy and in some animal models, evidence suggests that a process like that found in kindling does occur.[1]

Already in the 1950s and 1960s, numerous authors recognized the seizure-inducing potential of focal stimulation.[6] Here, Delgado and Sevillano demonstrated that repeated low-intensity stimuli to the hippocampus could lead to progressive increase of electrically evoked seizure activity.[7] Yet, it was not until the late 1960s that Graham Goddard recognized the potential importance of this phenomenon and coined the term 'kindling'.[8] Further research by Goddard on the characteristics of the kindling phenomenon led to his conclusion that kindling can be used to model human epileptogenesis, learning and memory.[9] The publication of these results opened a completely new niche for epilepsy research and has stimulated a significant amount of studies on the subject of kindling and its relevance to human epilepsy[6]

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