Your brain contains about 100 billion neurons. Each neuron is connected to other neurons like rose bushes planted close to one another. When the branches touch and overlap networks of neurons are formed. These connections are electrochemical synapses. Many hormones are released in the brain and support the growth and survival of these brain networks. Some of these hormones are released due to stressful or emotionally significant experiences while others are released due to new learning experiences or damaging brain events.
How you learn and remember is based on the strengthening and weakening of these neuronal circuits. This process allows the brain to respond and change and provides the basis for the word plasticity which is often used when discussing brain function. Brain neurons are able to adapt but there are limits to this adaptation beyond which cell death and brain damage do occur.
Your brain is able to self-organize and adapt to a changing environment. Stress, trauma, novelty and learning do affect brain structure and function. When stress hormones are released by your brain your ability to form new memories is affected. If a certain area of your brain is damaged by physical trauma or a lack of oxygen or blood flow your brain also has the ability for other undamaged populations of neurons to take over the job of the damaged neurons. This process involves the growth of new supportive networks that can perform the function of lost neurons and increase the performance and function of remaining working neurons.
Your brain is dynamic. The adult brain is not largely fixed and stable. Your ability to respond to brain stress through enhancement or rerouting of function is only now being understood. Old models that described the brain as being a hard wired circuit are not accurate. This capability allows you to continue an unending learning process throughout your life and provides hope for new treatments for those who are developmentally disabled, brain injured and for those who have psychological disorders.