. Neuroscience: neighbourly synapses. Nature. 2007 Dec 20;450(7173):1173-5. PubMed.

Recommends

Please login to recommend the paper.

Comments

  1. The Harvey-Svoboda paper does indeed usefully advance our understanding of the vital topic of the synapse-specificity of LTP. Although the paper does not mention it, other studies have shown that LTP occurs in an all-or-none manner, so that the "threshold-crosstalk" described by these authors is really equivalent to the "LTP-crosstalk" previously described by others (notably, Engert-Bonhoeffer).

    However, your summary is slightly wrong on one point: the Harvey-Svoboda evidence that depletion of calcium stores does not affect crosstalk does not rule out that calcium itself might be the "intracellular diffusible factor". This is still a very real possibility. The main argument Harvey-Svoboda advance against calcium is the evidence (in the supplementary material) that in the conditions of their experiments the spread of calcium from synapse to synapse is "only" 1 percent, a number that is not significantly different from zero. However, that number is clearly even less significantly different from 1 percent, a level that could (if repeated 30 times, as in their protocol) combine with sub-threshold calcium signals to trigger synapse-inspecific LTP.

    The main, and probably insuperable, difficulty, that synapses encounter in generating completely specific LTP is that they must remain well-coupled electrically to the parent dendrite. While this may seem a minor technicality, it may turn out to be the single most important problem the brain faces, and responsible for much of its baffling circuitry.

    View all comments by Paul Adams

Make a Comment

To make a comment you must login or register.

This paper appears in the following:

News

  1. Keeping Up With the Joneses—LTP at Synapse Spurs Same in Neighbor