When a loved one dies, they leave behind their personal belongings, but what happens to their life experiences? Could we retrieve memories from the mind of a dead person?

Retrieving some parts of memories may be possible, but it’s likely to be technically difficult, Don Arnold, a neuroscientist at the University of Southern California, told Live Science.

With today’s technology, retrieving memories can go something like this. First, the set of brain cells, or neurons, that encoded a particular memory in the brain is identified and how they are connected is understood. These neurons are then activated to create an approximate neural network, a machine learning algorithm that mimics the way the brain works.

Memories are encoded by groups of neurons, Arnold said. Short-term and long-term memories are formed in the hippocampus. Other parts of the brain store different aspects of memory, such as emotions and other sensory details, according to the Cleveland Clinic. Groups of neurons associated with a single memory leave a physical trace in the brain called an engram, Arnold said.

Neuroscientists have identified engrams in the hippocampi of the mice’s brains. For example, in a 2012 study published in the journal Nature, researchers found the specific brain cells associated with a memory of a fear-inducing experience.

If scientists had a complete model of the human brain (which they don’t have yet), they could theoretically pinpoint the location of the memory they wanted to retrieve, Arnold said.

However, human memories can be complex, especially long-term memories that may be linked to locations, relationships or skills, according to the Cleveland Clinic. Retrieving a dead person’s memories is even more complicated because the discrete parts of the memory are scattered throughout the brain. For example, sensory details that can also be stored in the parietal lobe and sensory cortex.

Neurons within a given engram are connected through synapses, the spaces between neurons where electrochemical signals travel, according to the National Library of Medicine. When a memory is activated, it sets off a chain of firing synapses between these groups, which can be stored in different parts of the brain. First, the neurons that were active during the initial event compose an engram. But over time, there is evidence that memories move to different locations as they consolidate in the brain, Arnold told Live Science in an email. “You get this kind of cascade of neurons that encode these different things, and each one of them connects to this graph.“, he said.

Simply cutting out the cells that make up the egram would not be a good recovery method. The engram isn’t actually the memory — it’s just where the memory is stored, Arnold said. So even if the engram were found, either through modeling or an experiment on someone while they were still alive (which is unlikely), it would be difficult to recreate the original event as experienced by the dead person.

“Memory is highly reconstructive, meaning you remember parts of an event but don’t really understand the wholeCharan Ranganath, director of the Memory and Plasticity Program at the University of California, Davis, told Live. Science. It’s an economical way of forming memories, he said, because the brain can use things it already knows to fill in the gaps and not have to make a new “record” for each part of the experience. For example, someone might remember eating chocolate cake and playing at their fifth birthday party. But they don’t remember other details, like which friends attended or whether it rained. However, they retain the overall memory of that experience.

The best neural network model would require a lifetime of brain scans of someone who repeatedly remembers events, Ranganath said. Then, perhaps, you could use the neural network to recreate a particular memory after someone dies. However, this assumes that memories are a static thing, like a file on a hard drive that plays back a series of events. Instead, memory is dynamic, Ranganath said.

“We imbue our memories with all kinds of meaning and perspective in a way that doesn’t necessarily reflect the fact“, he said. “We don’t repeat the past, we just imagine what the past might have been like.” All of this, he said, is in an effort to understand our past experiences as more than just a series of events. At the very least, the memories of a lifetime will die with the person who experienced it.