Question

How does the brain respond to stress, and how does stress affect the brain?

Answer 1

Ans: Cortisol is known as the stress hormone. The hypothalamus–pituitary–adrenal (HPA) axis acts to release cortisol into the blood stream. When high amounts of cortisol interact with the hypothalamus, the HPA axis will slow down its activity. Cortisol helps the brain to think clearly, sends energy to important muscles, and increases heart rate and breathing.

Another important brain structure involved in the stress response system is called the amygdala, the brain structure that actually detects stress and tells the HPA axis to respond. This structure is the size of a small kidney bean.  It is located in the middle of the brain. It can detect both emotional and biological stressors. An emotional stressor is something in the environment that may cause us to feel scared, sad, or frustrated, like the bear. A biological stressor is internal stress felt by the body, because of an injury or illness. he amygdala shares a special connection with another part of the brain called the prefrontal cortex. Its main job is to control the emotional responses to stress by regulating the amygdala. The prefrontal cortex is a big region in the front of the brain and it is called the control center becasue it helps to control our thoughts and actions. The main job of the prefrontal cortex is to control our emotional responses to stress so that we do not get too stressed out. The amygdala quickly signals a threat or stress in the environment, and the prefrontal cortex helps the amygdala to see stressful events as a little less scary or frustrating.

Chronic stress like being overworked or having arguments at home can affect brain size, its structure and how it functions. As described above that when we face a stressful situation our HPA axis is activated and corsitol hormone is released but high level of cortisol over a long period of time wreak havoc on our brain.

• The rising level of cortisol detriorate the electrical signals in the hippocampus, the part of brain associated with learning memory and stress control. Hippocampus also inhibits the activity of HPA axis, so when it weakens so does our ability to control stress.

• Too much of cortisol results in the loss of synaptic connection between neurons and shrinking of the prefrontal cortex, the part of the brain that regulates behaviour like concentration, decision making, judgement and social interaction. So chronic stress will leads to depression and eventually Alzheimer's disease.

• The brain is made up of neurons and support cells, known as "gray matter" responsible for higher-order thinking such as decision-making and problem-solving. But the brain also contains what is known as "white matter," which is made up of all the axons that connect with other regions of the brain to communicate information. White matter is so named due to the fatty, white sheath known as myelin that surrounds the axons that speed up the electrical signals used to communicate information throughout the brain. The overproduction of myelin due to the presence of chronic stress doesn't just result in a short-term change in the balance between white and gray matter—it can also lead to lasting changes in the brain's structure.

One example of the imapct of stress on our brain:

Researchers from the University of California—Berkeley performed a series of experiments looking at the impact of chronic stress on the brain. They discovered that such stress creates more myelin-producing cells, but fewer neurons than normal. The result of this disruption is an excess of myelin in certain areas of the brain, which interferes with the timing and balance of communication.