Research Focus: What is a Phantom Limb?

1. Research Focus: What is a Phantom Limb? Section G Module 3

2. Definition and Data:What is Phantom Limb? • Very few things are as puzzling as someone feeling a limb that isn’t there • Phantom Limb is the feeling sensations or movements coming from a lib that has been amputated– It is extremely vivid as if the limbs were present • Some patients felt their limb stuck in a particular position

3. Answers: Old and New • Sensations come from cut nerves in the stump • Some felt that the nerve endings were cut and remained in the stump • When nerves were cut near the spinal cord the phenomenon remained so this was ruled out • Sensations come from the Spinal Cord • The sensations could originate in the spinal cord • Some who have had severed spinal cords continued to feel the pain so this was ruled out

4. Answers: Old and New • Sensations come from body image stored in the brain • Researchers have enough data to point to the fact that it must be the brain itself • Based on sensations from body parts, the brain pieces together a complete body image • The brain can then generate sensations as coming from any body part, even if it is a phantom limb • This is shows that the brain sometimes functions in mysterious ways

5. Cultural Diversity: Plants & Drugs Section H Module 3

6. Cocaine: Blocking Reuptake • South American Indians have chewed coca leaves for about 3,500 years • They do this to relieve pain and hunger • Pg 59 Picture • Dopamine is a neurotransmitter that is released and reaches receptors and opens the chemical locks and activates neurons • After a while the neurotransmitter is removed and transported back into the end bulb through a process known as reuptake

7. Cocaine: Blocking Reuptake • If reuptake does not occur the neurotransmitter would continually affect the neuron by remaining longer in synapse • Cocaine blocks reuptake so that dopamine remains longer in the synapse • Neurons are stimulated longer and you have physiological arousal and feelings of euphoria

8. Curare: Blocking Receptors • The Indians of Peru and Ecuador coat the ends of blow darts with Curare a paralyzing drug • Curare enters the bloodstream, reaches the muscles, and blocks receptors on muscles • Neurotransmitters that normally activate muscles, called acetylcholine is blocked and muscles are paralyzed • Once an animal is hit the muscles become paralyzed and paralysis of chest muscles used to breathe cease to function

9. Curare: Blocking Receptors • Curare stops neural transmission by blocking the muscles’ receptors • Today the active ingredient is used by doctors when they insert a breathing tube down a patient’s throat • The blood-brain barrier prevents some potentially harmful substances in the body’s blood supply from reaching the brain

10. Mescaline: Mimicking a Neurotransmitter • Peyote, a plant found in the southwestern part of the U.S., contains mescaline • Mescaline– is a drug that causes physiological arousal as well as visual hallucinations • Mescaline’s chemical keys are similar to those of the neurotransmitter nor epinephrine • Because they open the same receptors, mescaline produces its effects by mimicking the actions of nor epinephrine

11. Mescaline: Mimicking a Neurotransmitter • Cocaine, curare, and mescaline contain potent drugs that illustrate three different ways of affecting the nervous system • Researchers have also discovered numerous plants that affect neurotransmitters • Neurotransmitters are keys that turn the brain on and off • Alzheimer’s disease and Parkinson’s disease are diseases that turn off the brain