Why does our brain go “blank” when it comes to important moments?

Audit expert: Yin Tielun

Deputy Chief Physician, Department of Neurology, Airport Branch, Peking University Third Hospital

Many of you may have experienced this: you spend a long time preparing for an important exam, but when you look at the test questions in the exam room, you feel that they are familiar but you don’t know where to start. You can’t remember the knowledge points that you have reviewed repeatedly before. The more nervous you are, the more blank your brain becomes...

Sometimes, I have thought of a perfect answer to the teacher's question in class, or a great joke at a party with friends, but when I stand up to tell everyone the joke, my mind suddenly goes blank, and I can't remember a single word of what I just repeated many times...

Source: hippopx

What is going on in these situations?

How are memories formed?

What we perceive and learn in our daily lives need to go through three steps: acquisition, encoding, and storage before they become our memories.

The first is acquisition . The information we get from the outside world includes multiple sensory experiences, such as vision, smell, hearing, etc. Each sensory experience will activate a specific area in the brain, and then we have an initial feeling about things, that is, the first impression.

The second is encoding . By strengthening the synaptic connections established when the sensory experience occurred, our cerebral cortex, cerebellum, hippocampus, and amygdala can encode the information contained in the initial sensory experience into neural electrical and chemical signals.

Finally, there is storage . The signals mentioned above are encoded into a network structure and stored in structures such as the cerebral cortex, cerebellum, hippocampus and amygdala, forming basic short-term memory.

Source: hippopx

Taking learning as an example, learning is the initial storage of knowledge, and nerve impulses are transmitted from the hippocampus to the olfactory cortex to form a solid factor; while exams are the output of memory storage, and nerve impulses are transmitted from the olfactory cortex to the hippocampus to release the stored memory.

What we usually call "forgetting" refers to the change in the memory network structure or the incorrect input electrical signal. If the human memory network itself is changed due to brain damage, then we cannot rebuild the memory and it is difficult to retrieve the previous memory. However, if there is a problem with the input signal for a short period of time, there will be a short period of forgetfulness, which is usually called "water in the brain"; if the correct input signal is restored afterwards and the memory is successfully retrieved, it will suddenly become clear.

If some memories are frequently called up, the sensory experience they contain will be enhanced by the hippocampus, thus slowly becoming a stable long-term memory. On the contrary, if this part of the memory is not used within a certain period of time, the synaptic connection will slowly weaken, and after a period of time, the memory will slowly fade away.

How does stress affect memory?

In the two steps of memory acquisition and encoding, moderate stress can actually help the brain acquire sensory experiences and enter memory. When people are stimulated by external stress, the brain controls the adrenal cortex to release corticosteroids, which promotes the increase of hippocampal activity and helps consolidate memory. For example, when we have time pressure two weeks before the final exam, our memory during this period will become better than usual.

Source: pixabay

So why can't we remember the knowledge we need during the exam? The reason is that the human body's memory behavior depends on the prefrontal lobe, which controls the brain's thinking, attention and reasoning abilities. During the exam, our nervousness creates stress, and the brain defines this situation as a "dangerous situation," which in turn promotes corticosteroids to stimulate the amygdala, thereby inhibiting the activity of the prefrontal lobe, which causes our brain to go "blank." If we try to recall, it will further generate stress, leading to the secretion of more corticosteroids, forming a vicious cycle, making it even more difficult to recall the knowledge we need.

For the human body, excessive stress or long-term stress can cause varying degrees of damage to the brain . Chronic stress accompanied by long-term emotional tension and anxiety can lead to long-term continuous secretion of corticosteroids, causing overstimulation of the hippocampus, which can weaken our ability to form new memories.

How to deal with stress?

First, if you have anticipated the source and situation of stress, you can prepare yourself by simulating similar environments. For example, in the exam, in your daily practice, you should try to be consistent with the exam scene, such as preparing stationery, not walking around randomly during the exam, etc. You can also create a sense of time pressure during the exam by timing, and be as familiar with the exam process as possible. Such long-term practice will reduce your sensitivity to exam pressure. During the exam, if your mind is blank, you might as well take a few deep breaths, empty your mind, and put yourself into a calm state without anxiety, so that it will be easier to think and reason normally.

In fact, thinking back to the “mock exams” of all sizes we took in high school, many times they were a process of helping everyone adapt to this pressure.

Source: hippopx

As for daily work or study, we need to stabilize our emotions, reduce stress, and achieve a "moderate degree of relaxation". This requires us to combine work and rest, adhere to a healthy and sustainable work model, pursue high-efficiency work, and allow our body and brain to be relieved every once in a while.

In addition, you can also improve your concentration and avoid multitasking. In addition, we also need to pay attention to healthy eating, avoid overeating, and avoid eating too much high-calorie food. Physical exercise can also effectively cope with stress. Experiments have shown that increasing heart rate and breathing rate will change the chemical composition in the brain, which can reduce anxiety and improve happiness.

Appropriate stress can bring positive effects, and we can use stress reasonably. For example, when doing something, we can set a deadline for ourselves and deliberately create a tense atmosphere, which can help us improve our concentration and work efficiency in a short period of time.