This week's finds in the papers

Anders Sandberg (
14 Nov 1998 01:43:25 +0100

(am I crossoposting this too widely?)

Extending the lifespan of flies
Working memory constrains the prisoners' dilemma Communication can lead to cooperation in the single-shot prisoner's dilemma Neutrino propulsion
A pheromone guided robot
PAF, Estrogen and AF-DX 116 improve memory


Extended life-span and stress resistance in the drosophila mutant methuselah, Y. J. Lin and L. Seroude and S. Benzer, Science 282:5390, 943--6.

That selective breeding and genetic modifications can make C elegans and Drosophilia live longer is old news; this article is interesting because it identifies a single gene change that increases lifespan with 35%. This gene, mth, seems to be some kind of G protein coupled receptor. Experiments show that methuselah flies can withstand stress better than normal flies, both in the form of starvation, free radicals and high temperature. This seems to fit in with what has been observed in C elegans mutants. Overall, this article suggests that aging may be linked to stress resistance, and that even single genes can improve lifespan.

Theory of Cooperation

Working memory constrains human cooperation in the Prisoner's Dilemma, Manfred Milinski and Claus Wedekind, Proc. Natl. Acad. Sci. USA, 1998, 95, 13755-13758

An empirical experiment studying what strategies people use in the IPD when their memory is limited by a distraction task. As the memory load increases, the subjects tended to shift from pavlovian strategies
("win-stay, lose-shift") towards Tit for Tat; this fits quite well
what has been observed in simulations.

Communication and Cooperation, John H. Miller, Carter Butts, and David Rode (Submitted to J. Games and Economic Behavior)

Traditional wisdom says that in a single-shot prisoners' dilemma it is rational to defect, and that cooperation will not emerge. However, if the agents can communicate with each other and evolve, then brief bursts of cooperation can emerge even if they play single-shot PD with each other. These bursts seems to involve the emergence of more complex communication which is used to "make deals".

Physics / Spaceflight

Neutrino Propulsion for Interstellar Spacecraft, J. A. Morgan

Another fun kind of propulsion; by exploiting parity violation in weak interactions it is possible to create anisotropic neutrino emissions, which would allow rest mass directly to impulse. The whole system looks rather unwieldy (involving slowing down and polarizing muons, using antimuons to make neutrons to regenerate target nuclei etc), but the concept is fun.


A Pheromone-Guided Mobile Robot that Behaves like a Silkworm Moth with Living Antennae as Pheromone Sensors, Yoshihiko Kuwana and Isao Shimoyama, International Journal of Robotics Research vol 17 no 9 Steptember 1998 pp 924--933

A small robot is controlled by signals from moth antennae fed through a very simple neural network, making it able to seek out pheromone sources.


Effects of posttraining intrahippocampal injections of plateletactivating factor and PAF antagonists on memory, L. A. Teather, M. G. Packard and N. G. Bazan, Neurobiol Learn Mem, 70:3 349-63, nov 1998

Platelet Activating Factor injected in the hippocampus has been shown to improve memory (Izquierdo95); this paper shows both this effect
(and that a structurally similar derivative has no effect) and that
PAF antagonists impair memory. PAF only acts if injected close to the training, 2 hours later it has no effect. This seems to suggest that PAF plays a role in the hippocampal memory consolidation process.

Estrogen improves performance of reinforced T-maze alternation and prevents the amnestic effects of scopolamine administered systemically or intrahippocampally, A. J. Fader, A. W. Hendricson and G. P. Dohanich, Neurobiol Learn Mem, 69:3, 225-40 may 1998

Estrogen seems also to have memory improving effects, at least when given to ovariectomized rats. It also can protect against the effects of scopolamine.

AF-DX 116, a presynaptic muscarinic receptor antagonist, potentiates the effects of glucose and reverses the effects of insulin on memory, S. R. Kopf, M. M. Boccia and C. M. Baratti, Neurobiol Learn Mem, 70:3, 305-13, nov 1998

Glucose improves memory , and AF-DX 116 seems to enhance the effect of it. The drug seems to be a blocker for autoreceptors inhibiting the release of acetylcholine, so it is possible that it acts by making the release of Ach (increased by the glucose) even higher. [This is an interesting possibilitiy for a long-lasting nootropic rather than one that must be used in conjunction with what is learned. ]

Yes, it seems like there are lots of ways of improving memory chemically; but deep down they might all be related or a few basic pathways.

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y