What Are the Brain, Neurons, and Seizures?

The best way to understand your child's epilepsy is to first understand how a healthy brain works. It may sound complicated, but the basic idea is quite intuitive, and once you grasp this foundation, almost everything your doctor tells you will start to fall into place.

The Brain: An Orchestra of Billions of Tiny Messengers

The brain is the body's control center. Thinking, speaking, walking, seeing, remembering, laughing, keeping the heart beating, regulating breathing — every function you can think of begins in the brain. The basic building block of the brain is called a neuron (nerve cell). A human brain contains roughly 86 billion neurons. These neurons are constantly talking to one another, much like every instrument in a huge orchestra playing in harmony.

Neurons communicate with each other through electrical and chemical signals. When a neuron is stimulated, it produces a small electrical current; when this current reaches the end of the cell, it triggers the release of chemical messengers called neurotransmitters. These messengers either excite or calm the next neuron. In a healthy brain, this exciting and calming is kept in perfect balance.

A Simple Analogy

Think of the brain like a city's electrical grid. Millions of light bulbs (neurons) are connected by wires and switch on and off in an orderly, controlled way. When all is well, the city is bright and well-ordered.

A seizure is like a sudden, uncontrolled overload in that grid: a group of bulbs starts flashing all at once and far too intensely. This sudden, synchronized, excessive electrical discharge is what a seizure is inside the brain.

What Happens in the Brain During a Seizure?

A seizure is a temporary event that occurs when a group of neurons in the brain discharges electrically in a much more intense, sudden, and highly synchronized way than normal. Where this abnormal electrical activity begins in the brain, and where it spreads, determines the outward signs of the seizure.

For example, if the abnormal activity begins in the area that controls movement, you may see stiffening or jerking in an arm or a leg. If it begins in the visual center, the child may see lights or colors. If broad networks involved in consciousness and awareness are affected, the child may briefly zone out and become unresponsive to their surroundings. This is why seizures are not all alike; depending on where they start and spread in the brain, they can look very different. In later chapters, we will look at these different seizure types in detail.

We want to stress a very important point: in most cases, this electrical storm in the brain stops on its own during a seizure. The brain's own braking mechanisms kick in and activity returns to normal. Afterward, the child may be tired, sleepy, or confused for a while; this is called the postictal period (the period after a seizure).

The Balance Between Exciting and Calming

The most important excitatory messenger in the brain is a substance called glutamate, and the most important inhibitory (calming) messenger is GABA. What most seizures have in common is that this balance temporarily tips toward excitation: either the brakes aren't working well enough, or the gas pedal is pressed too hard. Many epilepsy medicines aim to restore exactly this balance; some reduce excessive excitation, while others strengthen the calming effect. We'll come back to this logic when we talk about medications.

A Child's Developing Brain: Why Are Children Different?

A child's brain is different from an adult's; it is still developing, maturing, and forming new connections. This has two sides. On one hand, a developing brain may be more prone to seizures at certain ages, which is why some types of epilepsy appear only within specific age ranges. On the other hand, this flexibility of a child's brain (neuroplasticity) is a great advantage: children have a far greater capacity to heal and adapt than adults do. Many childhood epilepsies fade and disappear on their own as the brain matures.

The Regions of the Brain and Their Jobs

To understand why seizures can look so different, it helps to know that different regions of the brain have different jobs. The front part of the brain (the frontal region) is involved in movement, planning, and decision-making; the side regions (the temporal region) with memory, emotions, and hearing; the upper-back regions with touch and body position; and the very back with vision. Wherever a seizure starts and spreads, its signs take shape according to the job of that region. For example, a seizure that starts in the visual region may cause the child to see lights, while one starting in the movement region may cause stiffening in the arm.

This also explains why your doctor cares so much about "where the seizure started": the signs, almost like a map, point to the seizure's source in the brain. That is why observing the very first sign of a seizure closely (which way the eyes turned, which limb stiffened first) is so valuable for diagnosis.

The Concept of the Seizure Threshold

Every person has a "seizure threshold"; this is a way of describing how resistant the brain is to producing a seizure. In someone with a high threshold, seizures are hard to trigger; in someone with a low threshold, they come more easily. In children with epilepsy, this threshold is lower for various reasons. Triggers such as lack of sleep, fever, and stress can temporarily lower this threshold even further, making seizures more likely; medications, on the other hand, try to prevent seizures by raising the threshold. This simple idea explains why both avoiding triggers and taking medications regularly are so important.