STRESS AND THE BRAIN INTRODUCTION TO PSYCHOLOGY D. BAMBIC
A metaphor for neurons Your brain is made up of 100 billion nerve cells - about the same as the number of trees in the Amazon rainforest. Learning is about making connections between all these neurons. Stress impedes these connections.
THE EFFECTS OF STRESS ON THE BRAIN It is well known that toxic stress can harm the brain’s ability to form new memories, recall existing ones and even cause neurons to ‘shrink’. Stress can re-shape our brains.
Prenatal stress Prenatal stress can change the foetus’ brain permanently. Prenatal stress can lead to mood disorders and learning disabilities later in life. Stress in early childhood can lead to aggression and serious health problems in adult years.
Continued growth of brain A baby’s brain continues to develop long after birth. Stimulation and experiences are the nourishment for brain development. Stress is a negative experience that we must mitigate whenever possible.
Learning problems and mood disorders Stress in early life, even in the womb, can later lead to undesirable changes in behavior and the ability to learn and remember. Other consequences may be substance abuse and psychiatric disorders.
Even short term is not good! Prenatal stress can change the brain forever. Stress changes how genes are expressed throughout life. Even short-term stress can be harmful. Laboratory mice, which were immobilized for five hours and subjected to loud rock music. The ordeal reduced the number of delicate fibers that carry signals between neurons, an MRI brain scan of the stressed-out mice showed.
Stress and memory Chronic over-secretion of stress hormones adversely affects brain function, especially memory. Too much cortisol can prevent the brain from laying down a new memory, or from accessing already existing memories. Sustained stress can damage the hippocampus , the part of the limbic brain which is central to learning and memory. The culprits are "glucocorticoids," a class of steroid hormones secreted from the adrenal glands during stress. They are more commonly know as corticosteroids or cortisol .
Fight or flight response During a perceived threat, the adrenal glands immediately release adrenalin. If the threat is severe or still persists after a couple of minutes, the adrenals then release cortisol. Once in the brain cortisol remains much longer than adrenalin, where it continues to affect brain cells.
Shrinking hippocampus Long lasting, chronic stress also physically affects the brain. After laboratory rats were tightly restrained for six hours daily for 21 days, without food or water, the animals hippocampus - a brain region involved in learning and memory - shrank by 3%.
Cortisol and memory formation Have you ever forgotten something during a stressful situation that you should have remembered? Cortisol also interferes with the function of neurotransmitters, the chemicals that brain cells use to communicate with each other. Excessive cortisol can make it difficult to think or retrieve long- term memories. Thats why people get befuddled and confused in a severe crisis. Their mind goes blank because "the lines are down." They cant remember where the fire exit is, for example.