How does your brain remember where you put your glasses?

Image: courtesy Wei Deng, Salk Institute for Biological Studies

Image: courtesy Wei Deng, Salk Institute for Biological Studies

We do it all the time. Forget that is.

Or at least I do! Every day I will spend time at some point looking for my glasses - reading, general or sunnies, or my car-keys. It can get somewhat frustrating because it inevitably occurs when I need to be somewhere else, and I berate myself for not paying closer attention to my "putting down glasses" down activity.

We perform hundreds of activities daily, many of which are performed on autopilot never coming anywhere close to our level of conscious thinking. So how can our brain remember just where we did last put down our glasses or car-keys?

The part of our brain involved in storing and retrieving memories is called the hippocampus. Within this region is an area called the dentate gyrus that has now been shown to be responsible for distinguishing memories from different environments. What happens is that we use different groups of cells in this area when our brain is experiencing similar but slightly different events. Which then allows you to remember that you put your reading glasses down in the study, rather than like the time before, when you put them down on the kitchen bench.

Researchers from the Salk Institute using mouse studies have also discovered that when we try to recall the event, the brain does not always reactivate the same group of neurons that were active during the encoding of the memory.

Using separate groups of neurons in the dentate gyrus to represent separate but distinct memory, is called pattern separation and is just another demonstration of just how clever our brain is in helping us to navigate successfully around our environment.

Thank goodness for the dentate gyrus.

Wei Deng, Mark Mayford, Fred H Gage. Selection of distinct populations of dentate granule cells in response to inputs as a mechanism for pattern separation in mice. eLife, 2013; 2 DOI: 10.7554/eLife.00312