Saturday, July 27, 2019

Wisdom Of The Week

Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto, Canada, had also found evidence that the brain is wired to forget. Frankland was studying the production of new neurons, or neurogenesis, in adult mice. The process had long been known to occur in the brains of young animals, but had been discovered in the hippocampi of mature animals only about 20 years earlier. Because the hippocampus is involved in memory formation, Frankland and his team wondered whether increasing neurogenesis in adult mice could help the rodents to remember.

In a paper published in 2014, the researchers found precisely the opposite: rather than making the animals’ memories better, increasing neurogenesis caused the mice to forget more3. As contradictory as that initially seemed to Frankland, given the assumption that new neurons would mean more capacity for (and potentially better) memory, he says it now makes sense. “When neurons integrate into the adult hippocampus, they integrate into an existing, established circuitry. If you have information stored in that circuit and start rewiring it, then it’s going to make that information harder to access,” he explains.

Because the hippocampus is not where long-term memories are stored in the brain, its dynamic nature is not a flaw but a feature, Frankland says — something that evolved to aid learning. The environment is changing constantly and, to survive, animals must adapt to new situations. Allowing fresh information to overwrite the old helps them to achieve that.

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Hardt thinks that Alzheimer’s disease might also be better understood as a malfunction of forgetting rather than remembering. If forgetting is truly a well-regulated, innate part of the memory process, he says, it makes sense that dysregulation of that process could have negative effects. “What if what’s actually going on is an overactive forgetting process that goes haywire and erases more than it should?” he asks.

That question is yet to be answered. But more memory researchers are shifting their focus to examine how the brain forgets, as well as how it remembers. “There’s an increasing understanding that forgetting is a collection of processes in its own right, to be distinguished from encoding and consolidation and retrieval,” Anderson says.

In the past decade, researchers have begun to view forgetting as an important part of a whole. “Why do we have memory at all? As humans, we entertain this fantasy that it’s important to have autobiographical details,” Hardt says. “And that’s probably completely wrong. Memory, first and foremost, is there to serve an adaptive purpose. It endows us with knowledge about the world, and then updates that knowledge.” Forgetting enables us as individuals, and as a species, to move forwards.

“Evolution has achieved a graceful balance between the virtues of remembering and the virtues of forgetting,” Anderson says. “It’s dedicated to both permanence and resilience, but also to getting rid of things that get in the way.”


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