This brief video provides an overview of some of the common misconceptions about Parkinson’s disease, including causes, course, and outcome. For example, a single head injury will not cause Parkinson’s disease, at least there is no scientific evidence of it occurring. However, repeated head injuries might result in someone who is predisposed to Parkinson’s appear with symptoms earlier than they otherwise would be. This is the same with any environmental factors, such as pesticides or heavy metals (researchers have not shown a solid link between environmental hazards and Parkinson’s disease).
Watch this brief video for a few other misconceptions about Parkinson’s disease.
Charles Darwin’s work has had a huge influence on the world, specifically in the sciences. While Darwin hypothesized and theorized many things some parts of his research were more salient to psychology than other aspects. Darwin wrote that humans and animals were descended from a common ancestor (this would develop into research in the 1900s and 2000s showing that humans and animals share the majority of their genes). Because Darwin stated that humans and animals have a lot in common, the field of comparative psychology (i.e., studying animals to learn about human behavior) increased in popularity. Scientists had studied animals for thousands of years and made inferences about humans from those animals but Darwin’s theories led to researchers making inferences about human behaviors such as learning, memory, emotions, and even social interactions based on observations and experiments with animals.
Darwin’s research also led to research in psychology of individual differences. Before his theories, most researchers were trying to understand humans by looking at averages and similarities between people. They were just trying to understand the basic underlying constructs of human behavior. After Darwin, psychologists began investigating individual differences. It was not many years before the first modern intelligence test was developed by Binet in France. Intelligence is one area where many researchers focus on individual differences. Some psychologists are interested in what human traits make some people more successful than others. This is based largely on Darwin’s idea of natural selection where the strongest, adaptive, or creative species survive and other ones do not.
Darwin’s theories also had a large impact on psychology in general; much of psychology today has strong biological underpinnings. This traces largely back to Darwin. Psychologists often try to explain psychological concepts in light of biological processes. Some schools of psychology are almost strictly Darwinian, such as ethological psychology (the most famous 20th century ethological psychologist is Konrad Lorenz) and evolutionary psychology. Even though Darwin was not a psychologist, his theories have had a large and lasting impact on the field of psychology.
The brain is a magnificent organ. It is the reason humans spend 9 months in utero – to give the brain time to develop sufficiently. Human infants could even spend more time in the womb but due to birth canal size restraints, 9 months of development and head growth is all that mothers can handle. The human brain at birth has an over-abundance of neurons. Within the first 2 years of life, the brain prunes back the number of neurons as they are unneeded. Even in adulthood the number of neurons in the Central Nervous System (brain and spinal cord) is astounding – estimated at 100 billion! The number of connections between neurons – composed of dendrites, axons, and synapses – is estimated at 100 trillion.
At birth, few areas of the brain are well-myelinated. Myelin is a largely lipid-based substance (part of a type of glial cell; glial cells serve in mainly supportive roles to neurons) that wraps around the axons of neurons, like insulation around electrical wires, which increases the speed of transmission of action potentials – electrical impulses that travel down the axon when the signal is outgoing (or down the dendrites if the action potential is incoming). Myelination of the brain is not complete until into a person’s third decade of life, with the frontal lobes being myelinated last. The frontal lobes provide a lot of the oversight and control of the brain – decision making, language, and problem solving – so this slowness to myelinate in part explains children’s and adolescents’ often less-than-ideal reasoning (not that adults have wonderful reasoning all the time but adults often are more likely to think things through and be able to reason with complexity about situations and ideas).
So, the brain is such a complex and marvelous organ that it is a wonder that it develops so well most of the time.
I’ve posted some PDF slides that briefly cover the topic of the interaction between nature (biology/genes) and nurture (environment). Researchers used to fight over whether human behavior was attributable to nature or nurture. Now we just accept that it is a mixture of both, but researchers still discuss whether nature or nurture is more influential on a particular behavior.