Subcellular Imbalances in Synaptic Activity

Cell Rep. 2016 Feb 16;14(6):1348-1354. doi: 10.1016/j.celrep.2016.01.024. Epub 2016 Feb 4.


The dynamic interactions between synaptic excitation and inhibition (E/I) shape membrane potential fluctuations and determine patterns of neuronal outputs; however, the spatiotemporal organization of these interactions within a single cell is poorly understood. Here, we investigated the relationship between local synaptic excitation and global inhibition in hippocampal pyramidal neurons using functional dendrite imaging in combination with whole-cell recordings of inhibitory postsynaptic currents. We found that the sums of spine inputs over dendritic trees were counterbalanced by a proportional amount of somatic inhibitory inputs. This online E/I correlation was maintained in dendritic segments that were longer than 50 μm. However, at the single spine level, only 22% of the active spines were activated with inhibitory inputs. This inhibition-coupled activity occurred mainly in the spines with large heads. These results shed light on a microscopic E/I-balancing mechanism that operates at selected synapses and that may increase the accuracy of neural information.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Dendritic Spines / physiology
  • Dendritic Spines / ultrastructure
  • Excitatory Postsynaptic Potentials / physiology*
  • Hippocampus / cytology
  • Hippocampus / physiology*
  • Inhibitory Postsynaptic Potentials / physiology*
  • Patch-Clamp Techniques
  • Pyramidal Cells / cytology
  • Pyramidal Cells / physiology*
  • Rats
  • Rats, Wistar
  • Single-Cell Analysis
  • Synapses / physiology*
  • Synapses / ultrastructure
  • Tissue Culture Techniques