Valve Damage Question

This was an e-mail I sent to some of my gearhead friends today regarding the repair of my 1981 Toyota Tercel "Bopper":

Hi all,

I am finally putting Bopper back together and am almost ready to put the head back on the engine. Turning the head upside down to clean off all the old baked-on gasket material, I noticed one of the valves, third from right in attached picture (with a closer view in another picture) has some weird precipitate on it.

Since the old head gasket had failed and coolant was leaking into the cylinders, I am thinking that this is some weird antifreeze byproduct on the valve. It's very hard to get off.

I don't want to replace the valves, I want to finish this job and start driving Bopper again, but the question is, does this raise any alarm bells for y'all? I was just going to try to clean it as best I can and then put the head back on.  Have any of you seen this before?

Thanks,

Tim

And my mentor gearhead guru Mark's response: 

"It looks like carbon deposits to me.  As long as the valves are seating properly and there isn't carbon build up on the valve stem it should be fine.  The valve might run hotter than the others but that usually is only a problem on air cooled engines w/sodium valves.  Just make sure you scrape off as much of the old head gasket as possible and wipe down with acetone before putting the new gasket on.  And make sure the #1 piston is at TDC.  And follow the torque order..."

Thanks Mark! Anyone on the interwebs have any suggestion as well?

Pop Art Means Cutting Edge Neuroscience

In the latest issue of Science Magazine, a group of Israeli scientists recorded neurons of the hippocampus in humans with microelectrodes as part of  an epilepsy surgery. As the single neurons were recorded, the patients were played videos from various pop culture sources. After the movies were played, the subjects were then asked to recall what they saw. As you can see in the movie below, the sample neuron fires whenever Tom Cruise is shown, and, later, when the patient freely recalls what he saw on the TV, notice the neuron fires again approximately 1-2 seconds before the patient says "Tom Cruise." 

The video is amazing for its sheer pop art meets neuroscience combination. I thought it could be in a museum as an experimental modern art piece. But that aside, the big science ramification is that, perhaps, this neuron is where "the memory" of Tom Cruise resides. It also probably encodes more than Tom Cruise (as you can see in its sporadic response to other images), and whether it is truly where the memory trace exists can only be shown by either deactivating that neuron with GABA agonists / cooling, which is only done in animal models, or by stimulating that neuron and then asking if the patient immediately thinks of Tom Cruise. Even then, the neuron may still only be the "librarian" of the memory, and not the actual storage. Perhaps the brain doesn't make such distinctions in its storage mechanisms. 

These are tough problems to solve, but ultimately the most fascinating. I consider it even more interesting than the "C-word" problem. Oh brain oh brain, how ever do you store declarative memory?