Membrane Potential Dynamics of Spontaneous and Visually Evoked Gamma Activity in V1 of Awake Mice

PLoS Biol. 2016 Feb 18;14(2):e1002383. doi: 10.1371/journal.pbio.1002383. eCollection 2016 Feb.

Abstract

Cortical gamma activity (30-80 Hz) is believed to play important functions in neural computation and arises from the interplay of parvalbumin-expressing interneurons (PV) and pyramidal cells (PYRs). However, the subthreshold dynamics underlying its emergence in the cortex of awake animals remain unclear. Here, we characterized the intracellular dynamics of PVs and PYRs during spontaneous and visually evoked gamma activity in layers 2/3 of V1 of awake mice using targeted patch-clamp recordings and synchronous local field potentials (LFPs). Strong gamma activity patterned in short bouts (one to three cycles), occurred when PVs and PYRs were depolarizing and entrained their membrane potential dynamics regardless of the presence of visual stimulation. PV firing phase locked unconditionally to gamma activity. However, PYRs only phase locked to visually evoked gamma bouts. Taken together, our results indicate that gamma activity corresponds to short pulses of correlated background synaptic activity synchronizing the output of cortical neurons depending on external sensory drive.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Gamma Rhythm*
  • Interneurons / metabolism
  • Membrane Potentials*
  • Mice, Transgenic
  • Parvalbumins / metabolism
  • Pyramidal Cells / metabolism*
  • Visual Cortex / metabolism*

Substances

  • Parvalbumins

Associated data

  • Dryad/10.5061/dryad.4754J

Grant support

QP received funding for this work from the Fyssen Foundation. CMAP received funding from the Netherlands Organization for Scientific Research (NWO) Excellence Grant for the Brain & Cognition (project 433-09-208). LJG received funding from EC-FP7 ICT-FET project ‘‘BRAINLEAP,’’ grant n. 306502. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.