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The Powerful Lesson of the Grandma Neuron

Filed under The Owners Manual for Your Brain

In the 1960’s neuroscientists began searching for the Grandma neuron – trying to find for the exact location in our brain where the memory of our grandma resided. Little did they know that decades of repeated research would lead them to finally concede that there was no Grandma neuron, but that this conclusion itself presented them with startling implications.

Scientists had long assumed that our brains had a hierarchical structure, that is, a chain of command that might look something like the Hippocampus tapping into specific neurons storing specific memories.  For example, if you wanted to access the repository of the memory of your first kiss your Hippocampus would go to neuron 53,003.

Scientists wired up volunteers with brain activity reporting electrodes and sensors and showed them pictures of Grandmas and other familiar objects.  The assumption was that the photo would elicit activity  from a specific neuron as memories were activated. They waited expectantly for specific neurons to fire, but instead of a neat correlation between specific memories and specific neurons  they found that each time they were presented with Grandma memories a different neurons lit up.  In fact, sometimes the same group of neurons lit up in response to more than one kind of memory.

For decades scientists refined their electrodes and repeated the same test over, for surely memories had to reside somewhere inside the brain!  Finally MIT scientist Jerry Lettvin proposed that rather than being lodged in particular neurons, memory is distributed throughout the brain.  It was he who coined the term
“grandmother neuron” to represent the brain structure that housed the memory of grandma.

The realization was that with no one brain structure in charge, the brain was stronger and more resilient.  If, as in the fictional 2004 movie “The Eternal Sunshine of the Spotless Mind” with and Jim Carrey and Kate Winslet, we could just zap specific brain cells and thus erase the memory of a nasty breakup, the brain would be much more vulnerable to destruction.  The way it is we’d have to zap a pattern of neurons that is a continually moving target, and that is a much more difficult feat.

Although in our society hierarchy has come to give us a sense of comfort, since from boardrooms to governments to family we like to have a sense of “who is in charge”,  the truth is that there is more strength, potential and adaptability in structures, like our brains, that are decentralized.  What at first seems to be chaotic turns out to be one of the most powerful forces ever encountered.

 

 

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