Your brain can’t really tell the difference between seeing something and imagining it
When you picture an apple in your mind, your brain activates many of the same neurons as when you actually see one.
The idea that perception and imagination share common neural ground isn’t new. But the degree of overlap — and exactly which brain structures implement it — has remained hazy. A study published in Science now maps that relationship with unusual precision. The ventral temporal cortex, a region on the underside of the brain involved in object recognition, uses what the researchers call a shared representational code for both seeing and imagining objects. The same neural populations that fire when you look at a face also fire when you try to mentally picture one.
Participants were placed in an fMRI scanner and either viewed objects or imagined them. By comparing the patterns of brain activity across conditions, the researchers could show that the neural ‘signature’ left by a particular object was structurally similar whether the object was seen or imagined. Similar enough, in fact, that statistical models trained on visual data could identify which object a person was imagining — purely from their brain activity, without any visual input.
Why this matters for memory
The implications extend well beyond neuroscience curiosity. Memory is largely visual — when you recall a past event, you effectively ‘see’ it again in some form. If imagination and perception draw on the same neural infrastructure, memory actively recruits the visual system to reconstruct the past. That would explain why vivid imagination and sharp memory tend to go together: they may be expressions of the same underlying mechanism.
For people with aphantasia — a condition in which individuals are simply unable to form mental images — this research suggests that the shared system either functions differently or is less accessible. That has direct implications for how such individuals store and retrieve memories, a question that remains largely unresolved.
Relevance to cognitive decline
In the context of ageing and dementia, the findings take on additional weight. The ventral temporal cortex is among the regions affected relatively early in Alzheimer’s disease. If this area houses the shared code for both seeing and imagining, then damage to it would impair not only face and object recognition but also the ability to summon memories as mental images.
That is consistent with something Alzheimer’s patients and their families often describe: the loss isn’t only of names and facts, but of the vividness of memory itself. The past fades in a quite literal sense. Whether this mechanistic insight will eventually contribute to better diagnostics or intervention is unknown. But it provides, for the first time, a neural substrate for a phenomenon that has until now been difficult to pin down scientifically.