Fine-scale specificity of cortical networks depends on inhibitory cell type and connectivity

Nat Neurosci. 2005 Nov;8(11):1552-9. doi: 10.1038/nn1565. Epub 2005 Oct 9.


Excitatory cortical neurons form fine-scale networks of precisely interconnected neurons. Here we tested whether inhibitory cortical neurons in rat visual cortex might also be connected with fine-scale specificity. Using paired intracellular recordings and cross-correlation analyses of photostimulation-evoked synaptic currents, we found that fast-spiking interneurons preferentially connected to neighboring pyramids that provided them with reciprocal excitation. Furthermore, they shared common fine-scale excitatory input with neighboring pyramidal neurons only when the two cells were reciprocally connected, and not when there was no connection or a one-way, inhibitory-to-excitatory connection. Adapting inhibitory neurons shared little or no common input with neighboring pyramids, regardless of their direct connectivity. We conclude that inhibitory connections and also excitatory connections to inhibitory neurons can both be precise on a fine scale. Furthermore, fine-scale specificity depends on the type of inhibitory neuron and on direct connectivity between neighboring pyramidal-inhibitory neuron pairs.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Action Potentials / radiation effects
  • Animals
  • Animals, Newborn
  • Electric Stimulation / methods
  • Excitatory Postsynaptic Potentials / physiology
  • Excitatory Postsynaptic Potentials / radiation effects
  • In Vitro Techniques
  • Interneurons / physiology
  • Interneurons / radiation effects
  • Nerve Net / cytology*
  • Neural Inhibition / physiology*
  • Neurons / physiology*
  • Patch-Clamp Techniques / methods
  • Photic Stimulation / methods
  • Rats
  • Rats, Long-Evans
  • Statistics as Topic
  • Statistics, Nonparametric
  • Visual Cortex / cytology*