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Deciphering the information processing of synapses and neurons

Seeing key memory enzymes in action

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Graduate School of Medicine / Faculty of Medicine
2013/05/13

© The Authors. dFOMA imaging reveals unsuspected non-linearity in information processing governed by synaptic Ca2+-dependent enzymes, CaMKIIalpha and calcineurin, which are activated during synaptic plasticity and learning & memory.

A research group led by Hajime Fujii and Haruhiko Bito at the Department of Neurochemistry, Graduate School of Medicine, the University of Tokyo, has developed a novel imaging platform, dFOMA or dual FRET with Optical MAnipulation, and examined how the information contained in the frequency and number of neurotransmitter releases is transformed into postsynaptic Ca2+ signaling. Their results uncover striking rules performed by femto-nanoliter spaces near and at the synapse of neurons. Thus, Ca2+/CaM-dependent synaptic enzymes, such as CaMKII and calcineurin, are activated through non-linear decoding mechanisms. CaMKIIα activity sums supralinearly and senses both higher frequency and input number, acting as an input frequency/number decoder. In contrast, calcineurin activity summates sublinearly with increasing input number and shows little frequency-dependence, thus functioning as an input number counter. These results provide evidence that CaMKIIα and calcineurin are fine-tuned to unique bandwidths and compute input variables in an asymmetric manner. Deciphering the enzymatic information processing at synapses provides a better understanding of the signaling machineries underlying synaptic plasticity and learning and memory.

Press release {PDF] (Japanese)

Paper

Fujii H, Inoue M, Okuno H, Sano Y, Takemoto-Kimura S, Kitamura K, Kano M, Bito H,
“Nonlinear Decoding and Asymmetric Representation of Neuronal Input Information by CaMKIIα and Calcineurin”,
Cell Reports Online Edition: 2013/4/19 (Japan time), doi: 10.1016/j.celrep.2013.03.033.
Article link

Links

Graduate School of Medicine

Department of Neurochemistry, Graduate School of Medicine

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