A Tour of How the Brain Works

In this, Part 1, we demonstrate the actions of a normal Brain here. Once you are at the bottom of the page you can click the link to see Part 2. We acknowledge the help and support from © 2023 Alzheimer’s Association All rights reserved. Illustrations by Stacy Jannis.


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Your brain is nourished by one of your body’s richest networks of blood vessels. When you are thinking hard, your brain may use up to 50 percent of the fuel and oxygen.

With each heartbeat, arteries carry about 20 to 25 percent of your blood to your brain, where billions of cells use about 20 percent of the oxygen and fuel your blood carries.

The whole vessel network includes veins and capillaries in addition to arteries.

The Cortex: “Thinking Wrinkles”

Your brain’s wrinkled surface is a specialized outer layer of the cerebrum called the cortex. Scientists have “mapped” the cortex by identifying areas strongly linked to certain functions.








The left half controls movement on the right side of the body and the right half controls the left side

The Neuron Forest

Neurons are the chief type of cell destroyed by Alzheimer’s disease.

An adult brain contains about 100 billion nerve cells.

Branches connect the nerve cells at more than 100 trillion points. Scientists call this dense, branching network a “neuron forest.”

Signals traveling through the neuron forest form the basis of memories, thoughts, and feelings.

Cell Signaling

The real work of your brain goes on in individual cells. The neurotransmitters travel across the synapse, carrying signals to other cells. Scientists have identified dozens of neurotransmitters. Alzheimer’s disease disrupts both the way electrical charges travel within cells and the activity of neurotransmitters.

Signals that form memories and thoughts move through an individual nerve cell as a tiny electrical charge.

Nerve cells connect to one another at synapses.

When a charge reaches a synapse, it may trigger the release of tiny bursts of chemicals called neurotransmitters.

Signal Coding

100 billion nerve cells. 100 trillion synapses. Dozens of neurotransmitters. This “strength in numbers” provides your brain’s raw material. Over time, our experiences create patterns in signal type and strength. These patterns of activity explain how, at the cellular level, our brains code our thoughts, memories, skills and sense of who we are.

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