Scientists Build a Smarter Rat

destinyland writes "Scientists have engineered a more intelligent rat, with three times the memory length of today's smartest rats. Reseachers bred transgenic over-expression of the NR2B gene, which increased communication between the rat's memory synapses. Activating a crucial brain receptor for just a fraction of a second longer produces a dramatic effect on memory, as proven by the rat's longer memories of the path through a maze."

Comments

The rats' name is not 'Algernon', or is it?

[treczoks]

"Flowers for Algernon" was the first association that popped up from the depths of my mind...

We already knew it worked for mice

[tgibbs]

Kind of old news; the first report that NR2B overexpression improves rodent performance in some behavioral tests of learning and memory was was published in 1999. The nice thing here is that the investigators now have it working in the rat, which is a more difficult animal for transgenic studies, and a better one for behavioral work and electrophysiology.

Nevertheless, it raises an interesting question: if intelligence can be increased by something so simple as an increase in the expression of a single NMDA receptor subunit, why hasn't it already happened? Presumably, there is a selective advantage to improved learning and memory. Presumably, there is some kind of downside that balances that selective advantage. Are there other behaviors for which the rat is impaired?

Re:We already knew it worked for mice

[John Hasler]

> Presumably, there is some kind of downside that balances that selective
> advantage.

Higher energy requirements would be a good bet.

Re:We already knew it worked for mice

[debrain]

Presumably, there is a selective advantage to improved learning and memory. Presumably, there is some kind of downside that balances that selective advantage. Are there other behaviors for which the rat is impaired

As you suggest, there are two possibilities why this advantage hasn't occurred naturally:

1. It adds no selective advantage;

2. The advantage is outweighed by the costs.

There is a third possibility, namely that the set of mutations necessary to give rise to this advantage are too improbable to occur (or perhaps even fundamentally impossible).

Based on no knowledge whatsoever, I suspect that there probably is some selective advantage to higher intelligence in rats, over long enough periods of time. I hypothesize that the rats lack the ability to effectively dissipate heat from a highly active brain, and concurrently those evolutions that allow more effective dissipation of heat (e.g. baldness) are contrary to (or have never occurred concurrent with) the selective advantage of the intelligence. Perhaps we will breed intelligent, bald rats.

Re:We already knew it worked for mice

[ortholattice]

As you suggest, there are two possibilities why this advantage hasn't occurred naturally:

1. It adds no selective advantage;

2. The advantage is outweighed by the costs.

There is a third possibility, namely that the set of mutations necessary to give rise to this advantage are too improbable to occur (or perhaps even fundamentally impossible).

Maybe there is a 4th possibility. Everyone seems to be focusing on "survivability", but once that is overcome, reproduction becomes important. Look at the ostentatious displays of some birds that have nothing to do with survivability or might even be detrimental to it. Maybe a highly intelligent rat simply becomes less interested in sex, or is less able to attract females who might prefer the dumb macho rats. I don't know if a comparison to humans has any validity, but the most intelligent of our species are not necessarily the ones reproducing the most (or in some cases at all). This is in spite of the fact that we are intelligent enough to understand logically what is necessary to propagate our genes. In terms of the long-term evolution of humans, intelligence doesn't seem to be one of the characteristics we are selecting for, for better or worse.

Actually I wonder what the downside is

[OeLeWaPpErKe]

After all, if more memory were that simple, surely evolution would have changed that gene by itself. If it were a tradeoff, that would be much more logical.

So what did these rats lose ? Do they have gaps in long term memory ?

I'd watch out for the "no free lunch" idea holding true here too.

Re:Actually I wonder what the downside is

[maxwell demon]

Maybe the trade-off is that their brain simply needs more energy, which isn't great when food availability is the main factor limiting reproduction. Or maybe, the better memory simply doesn't help the rats too much in their natural habitat. After all, natural selection doesn't favour long memories, it favours large effective reproduction rates. If long memory doesn't lead to higher effective reproduction rates, it won't be improved by natural selection.

at what cost?

[Lord Ender]

Due to his enhanced memory, the rat could not push her out of his mind. The memories refused to fade with time. The slightest sight or scent would cause him not just to remember his intense passion and total devotion, but also to relive it, as if she were still there with him. Moments later, as reality returned, he inevitably re-experienced that October afternoon when she left. The despair cut to the bottom of his soul in a way far more intense than the original break-up had been, as shock had initially numbed his pain. No more. His perfect memory of perfect happiness lifted him up so high, the inevitable fall came from an unimaginable height, and terminal velocity does not apply to emotions.

After enduring this torture for what seemed an eternity, he finally gave in, and resolutely marched toward the wire-framed cheese, her angelic body still vivid in his mind...