Everything you wanted to know about spines, but were afraid to ask.

Modern optical neurobiology allows us to observe and control single synapses for the first time (though it is a little "depressing" to compare our in vivo 2-photon images (above) with those of Cajal-he wasn't so bad without an inffinity corrected microscope). Mike Häusser and colleagues have just published a review of spine function in Physiological Reviews. It is an amazing effort, having 884 references! We should all thank them over a beer at the SfN for doing all this hard work, gathering so much important information in one place.

P. Jesper Sjöström, Ede A. Rancz, Arnd Roth, and Michael Häusser Dendritic Excitability and Synaptic Plasticity Physiol. Rev. (2008) 88: 769-840. doi:10.1152/physrev.00016.2007

Neurobiology with caged calcium.

Impact factor (IF) is a strange and somewhat controversial metric. I have been accused of being a bit too obsessed with it. (Recall, IF=citations of a journal's papers from 2005 in 2006-07/number of papers published in 2005.) If one wants to do science that actually has impact, how can we judge our effectiveness? IF is certainly one objective means of trying to track the significance of a paper.

In the field of chemistry most journals have an IF of less than 5. JACS, Nano Letters, Angewandte Chemie, and Advanced Materials have IF of 7-10 (Angew is the tops, but its IF is boosted by having reviews, which JACS does not). The only chemistry journal with an IF>20 is Chemical Reviews. The Grand Dame of chemistry review journals has an IF=26. The May 2008 issue of Chem. Rev. is a "special" devoted to "Chemistry and Neuroscience". I wrote a contribution to this, at the invitation of the guest editor, Dirk Trauner (soon to move to Munich, apparently!). I want to thank Dirk for the honor of asking me to be part of this issue, and one of the reviewers of my review (who I suspect was Jakob Sorensen), for all the effort he put into correcting my mistakes!

"Neurobiology with Caged Calcium" Chemical Reviews (2008) 10.1021/cr078210i

The list

I am writing a review of two-photon uncaging of glutamate. Much as it is good for my career (?) to write reviews, I find them very painful to write as they suck time away from the lab. However, I thought this is going to be a short review, as there aren’t many publications in this field yet. Well it turns out there are far more than I thought! Since we published our first paper in 2001[1], there have been another 39 papers papers published using or reviewing two-photon uncaging of MNI-glutamate (historical list below: [2-40]). Many of these actually cite our original paper (highlighted in bold).

1. Matsuzaki M, Ellis-Davies GCR, Nemoto T, Miyashita Y, Iino M, Kasai H. (2001) Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons. Nat Neurosci, 4, 1086-92.
2. Andrasfalvy BK, Smith MA, Borchardt T, Sprengel R, Magee JC. (2003) Impaired regulation of synaptic strength in hippocampal neurons from GluR1-deficient mice. J Physiol, 552, 35-45.
3. Smith MA, Ellis-Davies GCR, Magee JC. (2003) Mechanism of the distance-dependent scaling of Schaffer collateral synapses in rat CA1 pyramidal neurons. J Physiol, 548, 245-58.
4. Yasuda R, Sabatini BL, Svoboda K. (2003) Plasticity of calcium channels in dendritic spines. Nat Neurosci, 6, 948-55.
5. Carter AG, Sabatini BL. (2004) State-dependent calcium signaling in dendritic spines of striatal medium spiny neurons. Neuron, 44, 483-93.
6. Matsuzaki M, Honkura N, Ellis-Davies GCR, Kasai H. (2004) Structural basis of long-term potentiation in single dendritic spines. Nature, 429, 761-6.
7. Bloodgood BL, Sabatini BL. (2005) Neuronal activity regulates diffusion across the neck of dendritic spines. Science, 310, 866-9.
8. Ngo-Anh TJ, Bloodgood BL, Lin M, Sabatini BL, Maylie J, Adelman JP. (2005) SK channels and NMDA receptors form a Ca-mediated feedback loop in dendritic spines. Nat Neurosci, 8, 642-9.
9. Noguchi J, Matsuzaki M, Ellis-Davies GCR, Kasai H. (2005) Spine-neck geometry determines NMDA receptor-dependent Ca signaling in dendrites. Neuron, 46, 609-22.
10. Sobczyk A, Scheuss V, Svoboda K. (2005) NMDA receptor subunit-dependent [Ca] signaling in individual hippocampal dendritic spines. J Neurosci, 25, 6037-46.
11. Tanaka J, Matsuzaki M, Tarusawa E, Momiyama A, Molnar E, Kasai H, Shigemoto R. (2005) Number and density of AMPA receptors in single synapses in immature cerebellum. J Neurosci, 25, 799-807.
12. Araya R, Eisenthal KB, Yuste R. (2006) Dendritic spines linearize the summation of excitatory potentials. Proc Natl Acad Sci U S A, 103, 18799-804.
13. Araya R, Jiang J, Eisenthal KB, Yuste R. (2006) The spine neck filters membrane potentials. Proc Natl Acad Sci U S A, 103, 17961-6.
14. Beique JC, Lin DT, Kang MG, Aizawa H, Takamiya K, Huganir RL. (2006) Synapse-specific regulation of AMPA receptor function by PSD-95. Proc Natl Acad Sci U S A, 103, 19535-40.
15. Gasparini S, Magee JC. (2006) State-dependent dendritic computation in hippocampal CA1 pyramidal neurons. J Neurosci, 26, 2088-100.
16. Losonczy A, Magee JC. (2006) Integrative properties of radial oblique dendrites in hippocampal CA1 pyramidal neurons. Neuron, 50, 291-307.
17. Scheuss V, Yasuda R, Sobczyk A, Svoboda K. (2006) Nonlinear [Ca] signaling in dendrites and spines caused by activity-dependent depression of Ca extrusion. J Neurosci, 26, 8183-94.
18. Soler-Llavina GJ, Sabatini BL. (2006) Synapse-specific plasticity and compartmentalized signaling in cerebellar stellate cells. Nat Neurosci, 9, 798-806.
19. Svoboda K, Yasuda R. (2006) Principles of two-photon excitation microscopy and its applications to neuroscience. Neuron, 50, 823-39.
20. Yasuda R, Harvey CD, Zhong H, Sobczyk A, van Aelst L, Svoboda K. (2006) Supersensitive Ras activation in dendrites and spines revealed by two-photon fluorescence lifetime imaging. Nat Neurosci, 9, 283-91.
21. Alvarez VA, Ridenour DA, Sabatini BL. (2007) Distinct structural and ionotropic roles of NMDA receptors in controlling spine and synapse stability. J Neurosci, 27, 7365-76.
22. Alvarez VA, Sabatini BL. (2007) Anatomical and physiological plasticity of dendritic spines. Annu Rev Neurosci, 30, 79-97.
23. Araya R, Nikolenko V, Eisenthal KB, Yuste R. (2007) Sodium channels amplify spine potentials. Proc Natl Acad Sci U S A, 104, 12347-52.
24. Asrican B, Lisman J, Otmakhov N. (2007) Synaptic strength of individual spines correlates with bound Ca2+-calmodulin-dependent kinase II. J Neurosci, 27, 14007-11.
25. Bloodgood BL, Sabatini BL. (2007) Ca signaling in dendritic spines. Curr Opin Neurobiol, 17, 345-51.
26. Bloodgood BL, Sabatini BL. (2007) Nonlinear regulation of unitary synaptic signals by CaV(2.3) voltage-sensitive calcium channels located in dendritic spines. Neuron, 53, 249-60.
27. Carter AG, Soler-Llavina GJ, Sabatini BL. (2007) Timing and location of synaptic inputs determine modes of subthreshold integration in striatal medium spiny neurons. J Neurosci, 27, 8967-77.
28. Ellis-Davies GCR, Matsuzaki M, Paukert M, Kasai H, Bergles DE. (2007) 4-Carboxymethoxy-5,7-dinitroindolinyl-Glu: an improved caged glutamate for expeditious ultraviolet and two-photon photolysis in brain slices. J Neurosci, 27, 6601-4.
29. Gasparini S, Losonczy A, Chen X, Johnston D, Magee JC. (2007) Associative pairing enhances action potential back-propagation in radial oblique branches of CA1 pyramidal neurons. J Physiol, 580, 787-800.
30. Harvey CD, Svoboda K. (2007) Locally dynamic synaptic learning rules in pyramidal neuron dendrites. Nature, 450, 1195-200.
31. Nikolenko V, Poskanzer KE, Yuste R. (2007) Two-photon photostimulation and imaging of neural circuits. Nat Methods, 4, 943-50.
32. Sabatini BL. (2007) Neuroscience: neighbourly synapses. Nature, 450, 1173-5.
33. Sobczyk A, Svoboda K. (2007) Activity-dependent plasticity of the NMDA-receptor fractional Ca current. Neuron, 53, 17-24.
34. Bloodgood BL, Sabatini BL. (2008) Regulation of synaptic signalling by postsynaptic, non-glutamate receptor ion channels. J Physiol, 586, 1475-80.
35. Busetto G, Higley MJ, Sabatini BL. (2008) Developmental presence and disappearance of postsynaptically silent synapses on dendritic spines of rat layer 2/3 pyramidal neurons. J Physiol, 586, 1519-27.
36. Honkura N, Matsuzaki M, Noguchi J, Ellis-Davies GCR, Kasai H. (2008) The subspine organization of actin fibers regulates the structure and plasticity of dendritic spines. Neuron, 57, 719-29.
37. Losonczy A, Makara JK, Magee JC. (2008) Compartmentalized dendritic plasticity and input feature storage in neurons. Nature, 452, 436-41.
38. Matsuzaki M, Ellis-Davies GCR, Kasai H. (2008) Three-dimensional mapping of unitary synaptic connections by two-photon macro photolysis of caged glutamate. J Neurophysiol, 99, 1535-44.
39. Tanaka J, Horiike Y, Matsuzaki M, Miyazaki T, Ellis-Davies GCR, Kasai H. (2008) Protein synthesis and neurotrophin-dependent structural plasticity of single dendritic spines. Science, 319, 1683-7.
40. Heine M, Groc L, Frischknecht R, Beique JC, Lounis B, Rumbaugh G, Huganir RL, Cognet L, Choquet D. (2008) Surface mobility of postsynaptic AMPARs tunes synaptic transmission. Science, 320, 201-5.