The following is an explanation from Johns Hopkins Press Health Book taken from Seizures and Epilepsy in Children Second Edition 1997 about seizures. I think it is a simplistic and effective model to help explain the interactions of the brain as it relates to seizures. I know it is a bit intellectual but enlightening.

Society: A Model for Disruptions and Seizures

The brain is a society of cells called neurons; it works through the interactions of individual neurons, one with another. Brief disruptions in the brain, that is, seizures, alter the interactions of these cells. To understand normal brain function and the disturbances of function called seizures, it may be helpful to conside another complex but more familiar structure - society, with its interactions and disruptions.

We all live in "society" and also in smaller communities: a family, a neighborhood, a church, a workplace, a town, a country. We are each members of multiple communities. Each of us is different: male or female, black or white, young or old. Our interactions create the social environment. So, too, is the brain a society, one composed of millions of individual cells (neurons), each with its own characteristics, each with its own interactions, each influencing and being influenced by its neighbors and by its local community. The brain has many different regions or communities and with these regions cells relate to each other in different ways. The regions also influence one another.

Throughout most brains, as within most soieties, these interactions occur in an orderly fashion, with few disruptions. But, occasionally, in a society, there are disruptions of varying magnitudes - like a holiday, a parade, an accident, a fire, a strike. Some interruptions occur more often in some communities than others; unpleasant disruptions, for example, occur more frequently in big cities with a greater diversity of people and more multiple interactions than in rural environments. After these "blips" in the normal pattern of life, communities usually resume their previous tempos quickly and return to normal activities.

But occasionally such disruptions are more intense. Perhaps lves are lost in a fire. The community is disrupted, its ordinary functions come to a halt, it grieves, it holds memorial services. Interactions among citizens are changed, not forever probably, but for a longer period of time than if a parade had passed by. The response of the community will depend on multiple factors - its ethnic heritage, its size its age, and the interrelationships within the community. Some disruptions spread more widely and involve larger segments of the community, the region, the country or the entire society. A strike of bus drivers or rail workers may affect the whole region. A march for a popular cause may mobilize a community or a nation.

Similarily, within the brain, communities of cells and areas of the brain interact a their own pace - different paces for different regions. These interactions in the brain are assessed by the EEG, a record of the minute amounts of electircal activity that brain cells give off as they relate to each other. The normal EEG appears as a series of wiggly lines, with rhythms seeming to move almost at random across the paper. The electrical activity measured varies from one area of the brain to another. But on rare occasions a "blip" appears among these wiggly lines, a small jolt of electricity, a "spike". This spike is like the minor episode, such a an automobile accident, that disrupts a community briefly. The brain quickly resumes its activity. Such spikes on the EEG are of litttle consequence. Only when they recur frequently in one area of the brain is it evident that that particular community of cells is prone to disruption.

When an electical disturbance of the brain is sufficiently stong, sufficiently disruptive, and localized, it may be seen as twitches of a hand, a foot, one side of the face. It may spread throughout one side of the brain, a unilateral seizure, or it may spread throughout the whole brain causing a generalized seizure. Each of these disturbances is a single seizure, but a single seizure is not epilepsy. Two or more seizures are called epilepsy.

Within society there are soapbox orators or fiery speakers who stand on street corners, trying to cause disturbances, urging people to "take action." Most people walk by. Occasionally, some people stop, listen and then walk on. Some of the audience may get excited, but action virtually never ensues; they don't change their behavior and a demonstration does not begin. But on rare occasions, this fiery speaker arouses the surrounding crowd and a march or a demonstration occurs. It will not happen solely because he is an inspired speaker but because of the interaction between the speaker and the audience. The interaction must be sufficient to rouse the crowd to action. In the brain tiny scars or small abnormalitiies, are like the fiery speakers. Usually this abnormal tissue cause no disruptions or change in brain function. Just as a crowd may pay no attention to a speaker, so the surrounding cells may fail to resond to the abnormality, and then nothing happens. Change in function, a seizure, requires the interaction of the abnormal area and the community, of the abnormal focus and its surrounding neurons.

This susceptibility of surrounding neurons to interaction is termed "threshold". To understand a spike or a seizure, we must understand the level of arousal or "threshold" of the surrounding cells. If the brain's threshold is lowered it is more susceptible to the effects of the "fiery speaker" the scar, and a seizure is more likely to occur in that community of the brain. If the electrical activity from a scar interacts with mildly aroused surrounding cells, a local disturbance may appear as recurrent spikes on the EEG, but this is not a seizure. A seizure is a paroxysmal electrical discharge of neurons in the brain resulting in a alteration of function or behavior. A spike results when a small number of neurons react simultaneously. Only if sufficient numbers of neurons are recruited does the electrical activity, seen as a spike, cause behavioral changes that we refer to as a seizure.

The alteration of function or behavior that occurs in a seizure will depend on the magnitude and type of the disruption or disorganizaiton and on the "community" of the brain in which it occurs. Local disruptions of brain function are called "partial" seizures because only part of the brain is involved. Since each area of the brain has a different function, the manifestations of an electrical disruption or seizure will differ, depending on which area of the brain is involved. When a partial seizure affects one area of the brain, the manifestations may be twitching of the thumb, hand or face. If it affects another, there may be a tingling sensation, a peculiar smell, an unusual taste. In other areas, the seizure may lead to change in behavior - staring or alterations of awareness. All such seizures are caused by local (contained) disruption of normal electrical activity.

But as in a societal disruption, a seizure or demonstration may not remain confined to a local region. Depending on its intensity and on the threshold of the brain, the disturbance or seizure may become sufficiently severe, or indeed, the whole brain and become a generalized seizure.

Just as we do not understand exactly why demostrations begin, spread and end in a society, we also do not yet completely understand the factors that maintain the seizure focus in the brain or the interactions with the "crowd" of surrounding neurons. How does excitement lack of sleep, or a fever alter the threshold of the surrounding cells? What genetic and environmental factors influence the threshold? If we understood the multiple factors and interactions that cause disruptions in the brain, and the factors that cause these disruptions to stop, we could probably prevent seizures from occurring altogether. But we do not.

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