Recently a friend asked, “How’s the mincers?”
“The mincers are good”, I replied. “But there’s no improvement in the watch and chain.”
It’s Cockney rhyming slang. Mincers=mince pies=eyes. Watch and chain=brain.
I get the same question most days (although not in rhyming slang). Usually it’s, “How are your eyes now?”
And usually I just say something like, “My eyes are fine, but my brain is damaged. It’s probably recovered as much as it will now, but I’m getting by really well.”
After a year very few patients with damage to their visual cortex are going to experience any more neurological recovery. Of course we can continue to learn how use the sight we have left much better, and that can be very successful for many people. But it’s a workaround. We just learn to live with the loss. Could we regrow what was lost?
We all grow new neurons.
It often used to be said that at some stage of our development we get a kind of fixed quota of neurons and then it’s all downhill. So many will die every day, bad living or bad luck will murder extra ones daily, but they will inevitably trickle away and never ever be replaced.
This is the stuff of Reader’s Digest and sounds excitingly grim. But it’s too gloomy and not accurate. Recent research suggests for example that the process of memory formation actually involves neuronal growth every day. So the fixed quota of neurons theory is an inaccurate simplification.
All the same regrowth of damaged brain areas in humans is slight. Not because neurons are not created – they are – but because they cannot easily fit into the gap. The chemistry left behind from the death of the previous neurons is hostile.
But some animals can regrow damaged brain areas. Larvae such as tadpoles can recover completely from serious damage and indeed when a tadpole changes into an adult frog it rapidly re-engineers much of its brain. For example it has to adapt from hearing well under water (one set of frequencies, mainly from enemies, to be avoided) to hearing well above water (croaks, a different set of frequencies, mainly from other frogs, a key part of the frog’s love life).
So perhaps if we can pull the right switches human regrowth of the central nervous system – spinal cord and brain (which includes the retina, which is just a sort of bit of the brain that’s adapted to sensing light) – might be possible.
Possibly stem cells will do the trick. Or perhaps cells from elsewhere in the patient’s own body can succeed. Either way it’s not an impossible dream and real progress has been made quite recently. You’ll almost certainly have read of the paralysed patient who has been enabled to walk again. But other recent advances were improvements from injecting stem cells into the brains of patients who had suffered particular forms of stroke, and into the retinas of patients with a particular form of visual loss.
No-one went back to where they had been before. But the improvements are very encouraging. They won’t be routine therapy anytime soon, but they show there is surely a way forward.
I wasn’t looking for therapy myself. These new approaches have too far to go before they could benefit me. I’ve got a gap in my brain (millions of neurons died and the waste was shipped away by the body). Although I was horrified by this idea at first, as time goes by, a hole is just a hole. It hasn’t stopped me being me and in fact it’s taught me so much I wouldn’t have it otherwise.
But I’m really excited by the idea that in the future there could be a treatment for stroke damage. A sort of “hole in the head” operation.