The Human Brain

In order to design a learning experiment, we obviously need to understand how the brain works and how we learn. In order to understand how our brains work and how we learn, we need to understand a bit about our brain cells called neurons. Neurons are cells found both in your brain and in the nerves that run through your body. They’re highly specialized cells that resemble the cells we’ve seen so far this year, but they also have quite unique features.

The human brain contains billions of neurons. In this simple activity we’ll make models of a few neurons and connect them as they are connected in a brain. We’ll refer to our classroom brain throughout the unit.

· Use the paper plate to represent the cell body. This is the part that contains the nucleus which instructs the cell to produce chemicals called neurotransmitters. Neurotransmitters allow electrical signals to pass from one neuron to another. Neurotransmitters help us to move, to think, to feel emotions…to do everything. We’ll return to them in detail later.

· Using a hole punch and some ribbon, attach a few dendrites to the cell body. Dendrites are the arms which receive electrical signals from other neurons.

· Using some of the streamer, attach an axon to one end of the cell body. Axons transmit received electrical signals to other neurons. In some parts of the body (but not the brain) a neuron’s axon can be several feet long!

· Fray the ends of the axon to create the axon terminals. Axons have these branches so one cell can connect to many different cells.

· We’ll hang the neurons to create a mini-brain in the classroom.

o At the center of the room we’ll represent the “inner brain” or “limbic system”. This is the portion of our brain that develops before birth and gets “wired up” while we’re still a fetus. To model this, we’ll connect the axon terminals of one neuron to the dendrites of other neurons to create a network of connections. It is these networks through which electrical impulses travel constantly to execute the many tasks needed to keep us alive.

o Around these inner neurons we’ll hang some other neurons, but we won’t connect them yet. This represents our “outer brain” or “cerebral cortex”, the portion of our brain that gets “wired up” after we are born. Learning – anything – is simply the building of connected networks of neurons in our cerebral cortex.

Here are some images of neurons in the brain:

http://brainmaps.org

http://www.alz.org/braintour/neuron_forest.asp

The neurons of the brain receive information from the outside world and enable us to respond to that information. But how does information from the outside world get into the brain in the first place? In the two diagrams here, you can see that there are pathways of neurons throughout our body that relay information from the outside world to our brain. Our brain in turn is able to use neuron pathways to send signals to the rest of our body.

Nerves are bundles of axons working together to transmit signals over a relatively long distance in the body.

What is the “direction” of these nerves? We’ll discuss.

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