Summary
A missing trip, an unconscious influence and a puzzle-making metaphor frame the writer’s account of how lived experiences can escape conscious recall.
At a glance
Appearing awake does not necessarily mean an experience will later be consciously remembered. The article presents the writer’s explanation of memory gaps through disrupted hippocampal encoding, distinguishing conscious recollection from unconscious influences of past experience. Its discussion connects medication, alcohol and intense stress with memory disruption within that attributed account; it does not establish a diagnosis for every example.
“I really don’t remember.”
Again? It can feel as though the hippocampus has decided it needs a break. But how can a stretch of life disappear from memory when everyone else insists you were awake and acting normally?
One story, relayed through an American psychologist, concerns a man preparing for an overnight flight across the United States. Hoping to sleep well, he asked a doctor for a newly marketed sleeping medication. Then, wanting to sleep more deeply, he took twice the prescribed dose.
After returning, he discovered that he could remember nothing about the outbound flight. The entire three-day trip seemed never to have happened. Yet people who had seen him at his destination assured him that he had arrived and had appeared perfectly alert and normal.
Less dramatic situations raise a similar question. You drink enough to black out and cannot remember getting home. After an angry outburst, you cannot recall what you said. You rush to open your computer because a deadline is approaching, only to discover that the work is already finished—with no memory of when you did it.
Is someone misleading you? Is your memory malfunctioning? Could your brain already be letting you down while you are still young?
For the writer who recounts these examples, the explanation centers on a region deep inside the brain: the hippocampus, and its relationship with the memories we can consciously retrieve.
Being awake and remembering are different things
The writer groups these experiences under temporary amnesia, also sometimes called intermittent amnesia, and identifies transient global amnesia, or TGA, as a particularly common form.
In this description, the condition differs from fainting. A person remains awake, although their level of alertness may diminish. To someone nearby, they may still seem entirely normal.
Invoking a medical explanation, the writer describes TGA as a special manifestation of cerebral ischemia—insufficient blood flow to the brain—with sudden memory loss lasting less than 24 hours, followed by gradual improvement. The writer nevertheless presents the man’s missing three-day trip as an exception to that description.
Alongside cerebral ischemia, the account lists brain injury, stroke and psychological trauma as possible causes of temporary memory loss. That leads to the next question: how might a gap in memory arise when there has been no brain injury?
The writer approaches that question by distinguishing two forms of memory.
Memories we retrieve, and memories that influence us
Explicit memory is memory available to conscious recollection. You can deliberately think back and retrieve it.
Suppose you have finished lunch and are considering dinner. You recall what is available in the cafeteria or what is sitting in your refrigerator at home. Those consciously accessible recollections are examples of explicit memory.
Implicit memory, by contrast, is the unconscious influence of past experience on what you do now. You do not have to make a deliberate effort to remember the earlier experience for it to affect you.
The writer illustrates this with an imagined visit to a zoo. You are absorbed in a conversation with a friend about the monkeys. Nearby, someone keeps saying, “Rice, rice, rice…” You do not notice.
Later, your friend asks whether you would prefer noodles or rice. “Rice,” you answer immediately. You think you simply feel more like eating rice, without recognizing any influence from the person repeating the word earlier.
That is the distinction the example is meant to capture: an experience can influence a choice without being consciously recalled.
The hippocampus as a puzzle maker
The hippocampus is a brain region, not the little sea creature—or the ingredient used in traditional medicine. Its connection to the seahorse is its shape.
One of its important functions is memory encoding. The writer likens it to a skilled puzzle maker, bringing together the different elements of an event: bodily sensations, emotions, thoughts, facts and reflections. Connected in this way, they become a memory of the past.
In the writer’s model, implicit-memory fragments drift separately until focused attention activates the hippocampus. Only then does it begin integrating those pieces into a consciously accessible past experience: an explicit memory. The writer also maintains that the hippocampus continues growing and encoding explicit memories throughout life, helping us understand both the world and ourselves.
This model supplies the article’s explanation for a missing stretch of time. If the hippocampus cannot encode an experience, what happens to the pieces?
When the hippocampus “goes on strike”
The writer explains temporary amnesia through damage to, or inhibition of, the hippocampus. A physical impact or suppression of its functioning is compared to a temporary power failure: images and sensations can no longer be encoded into explicit memories.
Within this explanation, the experience does not become a coherent factual or autobiographical memory. Instead, its elements remain as implicit fragments outside conscious access. Because you cannot consciously retrieve them, you encounter a blank where a remembered event would ordinarily be.
Short-term inhibition is central to the account. The writer describes sleeping medication and alcohol as temporarily shutting down hippocampal functioning. Intense emotional states—rage, fear and especially high stress—are also said to cause damage or a shutdown.
The proposed stress mechanism involves excessive stress-hormone secretion, including an abundance of cortisol, suppressing normal hippocampal function and growth. The writer further claims that prolonged exposure to high stress can blur memory and leave the hippocampus smaller than that of other people.
The explanation then turns to another brain region, the amygdala. According to the writer, when explicit-memory formation is impeded, the amygdala releases more adrenaline, strengthening the formation of implicit memories. In this account, difficulty forming a conscious record can coexist with an intensified accumulation of unconscious fragments.
Consider the vacation the writer imagines. You are visiting a place when a phone call brings an urgent work assignment. You try to keep sightseeing while completing the work, under intense pressure and holding down your feelings.
The illustration portrays cortisol and adrenaline as altering the brain, particularly the hippocampus, making explicit memories harder to form while implicit memories accumulate.
Once home, you find that you cannot remember what you did there. Someone asks about the trip, and you struggle to recall it. What surfaces may be a broad blank or a few images that will not connect. At times, you may also feel aversion or irritability without understanding where it comes from. The writer links these reactions to fragments of that pressured experience.
The thought of a temporary interruption is unsettling enough. What would life feel like if the ability to remember new events were lost for good? Days would pass, yet looking back might feel as though they had never been lived.
A life without an accessible record of new events
To illustrate that more lasting loss, the writer turns to H. M., a long-term research participant in the history of psychology.
In this account, surgery removed his hippocampus and greatly diminished his ability to form explicit memories. He could remember almost nothing that happened after the operation. He might tell you a joke, then tell it again a few minutes later in exactly the same tone—and then repeat it again, and again.
The example sharpens the contrast between a hippocampus that temporarily “goes on strike” and a lasting loss of its contribution to new memories. Life continues, but the consciously accessible record of what has just happened may not keep pace.
Making room to notice the pressure
The writer describes temporary memory loss as common and usually limited in its effects. The closing discussion nevertheless turns to more serious situations.
One example is military personnel living under prolonged, high-intensity stress. Under extreme pressure, the writer says, people may develop severe hippocampal shrinkage that affects cognitive functioning.
The account also describes a pattern in people with post-traumatic stress disorder, or PTSD, following severe psychological trauma: the traumatic event is temporarily forgotten, yet fragments remain. What seems to have disappeared can later be triggered, returning intermittently in flashbacks that bring traumatic recollections and distress.
The article ends with a gentler, tentative question. If you have experienced a temporary gap in memory, might it be worth considering whether you have recently put yourself under too much pressure?
Perhaps you could try regulating your emotions or taking some appropriate distance from a stressful environment. Pay attention to what you feel. Make room for reflection, and look for ways to release pressure—so that, with greater vitality and freedom, you can let the memories of your life take shape.
Frequently asked questions
What is the difference between explicit and implicit memory?
Explicit memory is memory available to conscious recollection. Implicit memory is the unconscious influence of past experience on present activity, without deliberate recollection.
Does the article establish that every memory gap is transient global amnesia?
No. The writer groups several experiences under temporary amnesia and discusses TGA, but the account does not establish a TGA diagnosis for every example. It describes TGA as lasting less than 24 hours while presenting the opening three-day trip as an exception.
What does the article suggest about responding to excessive pressure?
The ending tentatively suggests considering recent pressure, regulating emotions, taking appropriate distance from stressful surroundings and making room for reflection. It does not promise that these steps will restore missing memories.
