11.5 The Brain
The brain in addition to thinking, receives signals from the senses and controls movement. Our body has both voluntary and involuntary movement. When we decide to do something like lift our arm and then do it that is voluntary movement. That is controlled by the large part of the brain called the cerebrum. When we walk we decide to walk but the small part of the brain, the cerebellum, is doing thinking that sends signal to our muscles and helps us keep our balance which we are unaware of. That is involuntary motion.
The brain was named by people who didn't know what we know today about the function of different parts. They named some of the parts after what they look like or where they are located or for what they thought they did. The amygdala looks like an almond and amygdala means almond in Latin. Thalamus means inner chamber. Pituitary means slimey because they thought incorrectly, that it channeled mucus to the nose. Cerebrum means brain and cerebellum means little brain..
In 1954, Olds and Milner completed experiments with rats to investigate which brain regions may be involved in rewards. They implanted electrodes at various points in the brains of the rats, who were then placed in a small chamber with a lever. When the rats pressed the lever, they would receive a mild burst of electrical stimulation to their brains.
Their results indicated that there were various areas in the brain where the electrical stimulation gave pleasure, so the rats will press the lever frequently to receive this rewarding sensation.
One of the rats in this experiment pressed the lever 7500 times in 12 hours to receive this electrical stimulation.
Eventually, these rats would sometimes choose to receive the electrical stimulation than eat food.
There is a lesson here, too much pleasure can kill you. You lose motivation to do what is necessary to survive.
Here is a video that shows the reward center of the human brain. It also shows how cocaine stimulates the reward center and makes you feel good temporarily.
The brain responds to levels of dopamine that are too high by regulating itself to become less sensitive to dopamine. One way it does that is by reducing the number of receptors in the reward pathway of the brain. Another way is by modifying the receptors to become less sensitive. When the number of receptors are too low or they become less responsive and you aren't full of cocaine you feel bad and need cocaine to raise dopamine just to feel OK. This is true for many other addictive drugs as well such as marijuana the opioids and even alcohol.
Opioids are a class of drugs that include the illegal drug heroin, fentanyl, and pain relievers available legally by prescription, such as oxycodone (OxyContin®), hydrocodone (Vicodin®), codeine, morphine, and many others. People who get involved in an accident through no fault of their own may need opioids to kill the pain and become addicted to them.
Many people who are addicted to drugs will spend all their money to get the drugs and when they run out of money they will steal money from others so that they can get more drugs. Many wind up homeless because they spend their rent money on drugs or they can't hold a job because their drug habit makes them unable to function well at their job. Many overdose on drugs or unknowingly buy drugs doped with fentanyl that can kill them. In 2021 alone, 106,699 drug overdose deaths occurred in the United States. There is a lesson on this web site with a video called Chasing the Dragon about people chasing after the drugs that ultimately get them.
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