What This Study Is About
Researchers investigated whether the brain uses the exact same "code" at the level of individual neurons when we see an object versus when we imagine it. They wanted to know if mental imagery—the ability to picture things in the mind—is truly a reactivation of our visual system or a separate process.
How They Studied It
The researchers worked with epilepsy patients who already had electrodes implanted in their brains for medical reasons. This allowed the team to record the activity of single neurons in the ventral temporal cortex, an area of the brain responsible for recognizing objects. Participants were asked to look at specific images and then later imagine those same objects while the researchers tracked their brain activity. They used a computer model to compare the patterns of "firing" neurons during both tasks.
What They Found
The study found that about 40% of the neurons that responded when a person saw an object also fired in the same way when the person imagined it. This suggests that imagination isn't just a vague "echo" of seeing; it actually uses the same specific visual code. The researchers also discovered that this brain activity was more closely related to the visual features of the object (like its shape) than to its meaning (like its name).
What This Might Mean
This suggests that for most people, imagining is like "running the visual system in reverse." It raises interesting questions about aphantasia—the inability to visualize. It is possible that people with aphantasia still activate these visual neurons but cannot consciously "see" the result, or perhaps their neurons use a slightly different code that doesn't reach their awareness. However, because this study focused on patients with typical imagery, more research is needed to confirm how these findings apply specifically to the aphantasic brain.
One Interesting Detail
The researchers were able to use the activity of just a small group of neurons to accurately reconstruct or "guess" which object a participant was looking at or imagining.