When I was in college I took a course on the brain. It was just a quick "survey" type of thing, but I found it fascinating. One of the things that stuck with me was the talk of the "grandmother neuron".

Probably all of us have had the experience of seeing someone far off in a crowd - too far to make out distinct features - but instantly feeling that we know that person. Or seeing your grandmother from a distance, even after a span of years, and instantly recognizing them.

http://www.newscientist.com/article.ns?id=dn7567

=== begin cut ==

In the 1960s, neuroscientist Jerry Lettvin suggested that people have neurons that respond to a single concept such as, for example, their grandmother. The notion of these hyper-specific neurons, coined “grandmother cells” was quickly rejected by psychologists as laughably simplistic.

But Rodrigo Quiroga, at the University of Leicester, UK, who led the new study, and his colleagues have found some very grandmother-like cells. Previous unpublished findings from the team showed tantalising results: a neuron that fired only in response to pictures of former US president Bill Clinton, or another to images of the Beatles. But for such “grandmother cells” to exist, they must invariably respond to the “concept” of Bill Clinton, not just similar pictures.

[...]

The team found similar results with another woman who had a neuron for pictures of Halle Berry, including a drawing of her face and an image of just the words of her name. “This neuron is responding to the concept, the abstract entity, of Halle Berry,” says Quiroga. “If you show a line drawing or a profile, it’s the same response. We also showed pictures of her as Catwoman, and you can hardly see her because of the mask. But if you know it is Halle Berry then the neurons still fire.”

Given more time and an exhaustive list of images, the team may well have landed upon other images that spiked the activity of the “Halle Berry” neuron. In one participant, the “Jen” neuron also fired in response to a picture of her former Friends cast-mate, Lisa Kudrow. The pattern suggests that the actresses are tied together in the memory associations of this particular woman, says Charles Connor, a neuroscientist at Johns Hopkins University in Baltimore, US.

These object-specific neurons may be at the core of how we make memories, say Connor. “I think that’s the excitement to these results,” he says. “You are looking at the far end of the transformation from metric, visual shapes to conceptual memory-related information. It is that transformation that underlies our ability to understand the world. It’s not enough to see something familiar and match it. It’s the fact that you plug visual information into the rich tapestry of memory that brings it to life.”

Journal reference: Nature (vol 435 p 1102)
=== end cut ===

Thoughts, concepts, memories, ideas, etc. are ultimately tied to the hardware. :-) We still don't understand much about how the hardware works, but we know that when it doesn't, then we have big problems...

Cheers,
Scott.