Synaptic democracy in active dendrites

J Neurophysiol. 2006 Nov;96(5):2307-18. doi: 10.1152/jn.00149.2006. Epub 2006 Jul 12.

Abstract

Given the extensive attenuation that can occur along dendritic cables, location within the dendritic tree might appear to be a dominant factor in determining the impact of a synapse on the postsynaptic response. By this reasoning, distal synapses should have a smaller effect than proximal ones. However, experimental evidence from several types of neurons, such as CA1 pyramidal cells, indicates that a compensatory strengthening of synapses counteracts the effect of location on synaptic efficacy. A form of spike-timing-dependent plasticity (STDP), called anti-STDP, combined with non-Hebbian activity-dependent plasticity can account for the equalization of synaptic efficacies. This result, obtained originally in models with unbranched passive cables, also arises in multi-compartment models with branched and active dendrites that feature backpropagating action potentials, including models with CA1 pyramidal morphologies. Additionally, when dendrites support the local generation of action potentials, anti-STDP prevents runaway dendritic spiking and locally balances the numbers of dendritic and backpropagating action potentials. Thus in multiple ways, anti-STDP eliminates the location dependence of synapses and allows Hebbian plasticity to operate in a more "democratic" manner.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials / physiology
  • Axons / physiology
  • Axons / ultrastructure
  • Calcium / physiology
  • Dendrites / physiology*
  • Dendrites / ultrastructure
  • Excitatory Postsynaptic Potentials / physiology
  • Models, Neurological
  • Pyramidal Cells / physiology
  • Pyramidal Cells / ultrastructure
  • Synapses / physiology*
  • Synapses / ultrastructure

Substances

  • Calcium