Why You Should Definitely Not Let Ben Carson Drill a Hole in Your Head

Ben Carson, recently appointed US Housing and Urban Development secretary, is a qualified neurosurgeon. You therefore expect him to have some impressive expertise on the brain. But given his claim in a controversial recent speech that he could stick electrodes in your hippocampus and have you recite verbatim a book you read 60 years ago, this expectation seems wildly optimistic, bordering on farcical. There are so many reasons why this is the case.

Human memory doesn’t work that way

The term “memory” is used a lot these days, but in the technological sense. Laptop memory, memory stick, SD card memory, and so on. “Memory” in this context is the means of storing data, to be retrieved later when needed, in the exact same form as when it was stored. That’s sort of the point. It would be a waste of everyone’s time if your device only stored the bits of information it liked, or tweaked them randomly all the time, and refused to retrieve important things when needed for no discernible reason.

But that is essentially how human memory works. Our brains are not merely bloated data banks resting in our skulls. They don’t just passively absorb every single thing we experience, and they haven’t really evolved to retain abstract information, hence revising for exams is so hard. Human memory is influenced by emotions, and context, and many other things. Memories with a strong emotional element (your first kiss, a traumatic car accident) are often the most vivid and easily recalled (sometimes to a debilitating extent).

Just the ability to even form and retain such meticulously detailed memories of a book you read, once, without making any special effort to remember it, already suggests a brain operating at superhuman levels. Even with recent, important things, most of our memories are concerned with the “big picture”, capturing the “gist” of events. The fine details are usually glossed over, or filled in by the brain later, usually in ways that make us look good.

Some people claim to have such photographic memories, but there is little to no evidence that these actually exist. The truth is, the idea that there exists in your brain a perfect memory of an entire book from 60 years ago is already highly dubious, and that’s not even the most fanciful part of Carson’s claim.

Memories aren’t all stored in one place

What exactly is a single human memory? What does it look like, in the physical sense? Current evidence (mostly) suggests that human memory is formed by synapses, the physical connections between brain cells, where they exchange signals.

The thing is, human memory processing has three stages; encoding, storage and retrieval. Encoding is where the memories are formed, based on the recent sensory information received by the memory systems. Storage is when the memories are laid down in a permanent fashion. Retrieval is when the memory is activated at a later date when the information it holds is needed. Basically, a memory needs to be created, put somewhere, and triggered as and when required.

To deliberately trigger a precise memory from the outside using electrodes, you’d have to know precisely where that memory is stored. While we did previously think long-term memories were stored in the hippocampus, more recent evidence suggests they’re actually spread throughout the cortex. So in order to activate a specific 60-year-old memory with electrodes, you’d need to find where it’s specifically stored. So you’re looking for some specific synapses in the biggest part of the brain, objectively indistinguishable from the hundreds of trillions of others there. For comparison, imagine having to find the family photos stored on your hard drive, but you can only look at the binary code, and have to identify the zeros and ones that represent your pictures from among the countless others.

Finding a specific memory in someone else’s brain is a bit like that, except orders of magnitude more confusing. And possibly lethal.

The hippocampus doesn’t work like that

The hippocampus, Carson’s chosen target, is vitally important for memory processing, nobody is doubting that. But it seems to be most important for encoding, forming memories. While it does have various other roles, this seems to be the main one. Carson claiming he can trigger very old memories by stimulating the hippocampus is tantamount to claiming he can find the first car you ever bought by going to the factory where it was made and randomly turning the machines on and off; there is sort of a link there, but that’s not really enough.

Admittedly, the hippocampus has other roles. It does seem to be involved in long term memory storage, at least for more recent memories, but these gradually migrate out into the cortex as newer memories are laid down behind them, like toothpaste being forced out of the tube.

The hippocampus also has a role in memory retrieval, but it’s nowhere near what Ben Carson is suggesting, or if it is capable of causing such precise retrieval we have no way of knowing how to make it do this yet. We’re a very long way off from that. An entire PhD project from as recently as 2010 just about managed to show that the hippocampus is involved in very specific forms of recent memory retrieval in rats! That was new information at the time, and science doesn’t progress nearly quickly enough to go from that to allowing pinpoint activation of decades-old human memories by often-confused creationist retired neurosurgeons today.

And if you’re sceptical that I’d go to the extent of reading an entire PhD thesis just to flesh out a topical article, I can assure you I have indeed read it. And wrote it. IT WAS MY PHD! For the first time since starting this often-farcical semi-satirical science blog, I can legitimately quote my own published research, because when it comes to the role of the hippocampus in memory retrieval, this is legitimately my area of expertise.

It’s quite a rush, isn’t it. Is this how proper scientists feel all the time? If nothing else, Ben Carson caused this to happen, so I should at least be grateful for that.

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