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Synaptic tagging and capture in a biophysical model

Benjamin Auffarth1* and Panayiota Poirazi1
  • 1 IMBB, FORTH, Greece

There is wide consensus that synaptic plasticity (prominently long-term potentiation; LTP) is the underlying mechanism for learning and memory storage (cf Nabavi 2014). Open issues include the molecular pathways and networks and structural processes leading to functional and structural changes at the synaptic and dendritic levels in terms of channels and spines. Synaptic tagging and capture (STC; Frey and Morris 1997; Redondo and Morris 2011) is a predominant model for investigating LTP. According to the STC hypothesis, the mechanisms underlying LTP can be separated into independent processes for the generation of plasticity-related products (PRPs) and the setting of a synaptic tag. We know from many studies that dendritic branches act as computational units, given the availability of ionic mechanisms and local compartmentalization of synaptic interactions (Branco and Hausser 2010; Poirazi et al 2003; Frey, 2001). In order to investigate the effects of dendritic compartmentalization on memory formation, we implemented a model of STC in the NEURON platform, incorporating both mechanisms for short-term plasticity and late LTP (l-LTP). Synapses are confined within spines and include numerous biophysical channels and receptors. Our l-LTP mechanism demonstrates the association of memories to synapses and dendrites. We show that local diffusion leads to increases in synaptic weights for neighboring spines, showing the plausibility of the synaptic clustering in memory storage (Poirazi 2001; Govindarajan 2006). The first figure shows the dendritic excitatory postsynaptic potential on tetanic stimulation of 2x100Hz. The second figure shows consolidated synaptic plasticity at the stimulated synapse (blue), and two neighboring synapses (green and red).

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Figure 3
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Acknowledgements

This work is supported by the EC-FP7-PEOPLE sponsored NAMASEN Marie-Curie Initial Training Network (grant n. 264872).

References

Nabavi, Sadegh, et al. "Engineering a memory with LTD and LTP." Nature(2014).
Branco, Tiago, and Michael Häusser. "The single dendritic branch as a fundamental functional unit in the nervous system." Current opinion in neurobiology 20.4 (2010): 494-502.
Govindarajan, A., Kelleher, R. J., & Tonegawa, S. (2006). A clustered plasticity model of long-term memory engrams. Nature Reviews. Neuroscience, 7(7), 575–83. doi:10.1038/nrn1937
Poirazi, Panayiota, Terrence Brannon, and Bartlett W. Mel. "Pyramidal neuron as two-layer neural network." Neuron 37.6 (2003): 989-999.
Redondo, R. L., Okuno, H., Spooner, P. a, Frenguelli, B. G., Bito, H., & Morris, R. G. M. (2010). Synaptic tagging and capture: differential role of distinct calcium/calmodulin kinases in protein synthesis-dependent long-term potentiation. The Journal of Neuroscience : The Official Journal of the Society for Neuroscience, 30(14), 4981–9. doi:10.1523/JNEUROSCI.3140-09.2010
Frey, Uwe, and Richard GM Morris. "Synaptic tagging and long-term potentiation." Nature 385.6616 (1997): 533-536.
Redondo, Roger L., and Richard GM Morris. "Making memories last: the synaptic tagging and capture hypothesis." Nature Reviews Neuroscience 12.1 (2011): 17-30.
Poirazi, Panayiota, and Bartlett W. Mel. "Impact of active dendrites and structural plasticity on the memory capacity of neural tissue." Neuron 29.3 (2001): 779-796.

Keywords: Dendrites, functional connectivity, pyramidal neuron, compartmental modeling, Neuronal Plasticity, LTP, LTP (Long Term Potentiation), STP, Hippocampus, CA1 pyramidal neuron, CA1

Conference: 4th NAMASEN Training Workshop - Dendrites 2014, Heraklion, Greece, 1 Jul - 4 Jul, 2014.

Presentation Type: Poster presentation

Topic: functional or structural plasticity and homeostasis

Citation: Auffarth B and Poirazi P (2014). Synaptic tagging and capture in a biophysical model. Front. Syst. Neurosci. Conference Abstract: 4th NAMASEN Training Workshop - Dendrites 2014. doi: 10.3389/conf.fnsys.2014.05.00048

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Received: 21 Jan 2014; Published Online: 18 Jun 2014.

* Correspondence: Dr. Benjamin Auffarth, IMBB, FORTH, Heraklion, Crete, GR 711 10, Greece, auffarth@imbb.forth.gr