"Plasticity Inducing Stimulus."

Sabatini and co-workers have a nice paper in this week's Neuron (11 December 2008). They use 2-photon uncaging of glutamate to induce spine head enlargement. This technique was of course invented by Haruo Kasai and Masanori Matsuzaki in 2004. It has also been used by Karel Svoboda and co-workers to great effect. Interestingly all 3 labs see more or less the same structural changes at targeted spine heads (see figure). Small spines undergo rapid enlargement (200-300% increase in volume), however only part of this increase in maintained for hours. Two other labs have also used Kasai's method to induce LTP at visually identified spine heads. Yasuda (Duke) and Hayashi (MIT) have both had abstracts at the past SfN annual meetings doing similar experiments to Sabatini's lab. They are all trying to parse out the details of the signaling processes involved in the initiation and maintenance of LTP used GFP-labeled proteins. Lots of interesting details are starting to emerge from these studies. Sabatini coins a new term for the Kasai/Matsuzaki LTP protocol: "Plasticity Inducing Stimulus" or "PS" for short. It is a pity he didn't add an extra I and S to this, that would have been very amusing.

Structural basis of long-term potentiation in single dendritic spines. Nature (2004) 429:761-6.

Locally dynamic synaptic learning rules in pyramidal neuron dendrites. Nature (2007) 450:1195-200.

Destabilization of the Postsynaptic Density by PSD-95 Serine 73 Phosphorylation Inhibits Spine Growth and Synaptic Plasticity. Neuron (2008) 60:788-802