Michael Mullan presents the 2nd part of : A Journey Through the Effects of Alzheimer’s on the Brain
read part 1 here
6 Signaling in the cells
Thoughts and memories travel through nerve cells as minute electrical charges.
One nerve cell connects to another one at synapses. As the tiny electrical charge reaches the synapse, it can release a burst of chemicals, known as neurotransmitters. The function of neurotransmitters is to carry signals to the other cells across the synapse. Scientists have discovered dozens of different neurotransmitters.
Alzheimer’s is responsible for disrupting how electrical charges can travel while it also disrupts neurotransmitter’s activity.
7. Signal coding
With billions of nerve cells and trillions of synapses the power of the brain is sourced from numbers. Your experiences form patterns in the type of signals which explain how we are defined at a cellular level as your brain codes your memories, skills, thoughts and your sense of self.
The scan to the left is called a positron emission tomography (PET) this shows brain activity patterns that are linked to:
Reading of words
Thoughts about words
The red areas mark high activity levels through to the other end of the rainbow scale where yellow and violet mark low activity.
Your patterns change over the years as you have new experiences, meet different people and learn new things. Alzheimer’s changes patterns by disrupting nerve cells and the connections between them.
8. How Alzheimer’s Affects the Brain
Alzheimer’s causes the brain to shrink over time, killing nerve cells and leading to tissue loss. The effects are widespread.
A normal disease free brain
The brain with advanced Alzheimer’s
A comparison of the two
9. Further changes in the brain
This is another dramatic view of the massive effects on the brain of advanced Alzheimer’s. The image is a crosswise slice of the brain.
On the Alzheimer’s side:
The cortex is shriveled, affecting the thought, planning and memory areas.
The hippocampus is especially smaller than other areas, this part of the cortex controls new memory formation.
The spaces in the brain, called ventricles, grow bigger
10. Beneath the Microscope
When viewed through the microscope scientists are able to see the devastating effects of the disease:
Alzheimer’s brain tissue has much less nerve cells and also synapses than a normal brain
Build up of protein fragments called plaques occurs between the nerve cells
The dying and dead nerve cells have tangles twisted strands made of other proteins.
Although scientists are not certain what leads to the death of cells and loss of tissue in a brain with Alzheimer’s, the tangles and plaques are the prime suspects.