Passive Transport Disrupts Grid Signals in the Parahippocampal Cortex

Curr Biol. 2015 Oct 5;25(19):2493-502. doi: 10.1016/j.cub.2015.08.034. Epub 2015 Sep 17.


Navigation is usually thought of relative to landmarks, but neural signals representing space also use information generated by an animal's movements. These signals include grid cells, which fire at multiple locations, forming a repeating grid pattern. Grid cell generation depends upon theta rhythm, a 6-10 Hz electroencephalogram (EEG) oscillation that is modulated by the animals' movement velocity. We passively moved rats in a clear cart to eliminate motor related self-movement cues that drive moment-to-moment changes in theta rhythmicity. We found that passive movement maintained theta power and frequency at levels equivalent to low active movement velocity, spared overall head-direction (HD) cell characteristics, but abolished both velocity modulation of theta rhythmicity and grid cell firing patterns. These results indicate that self-movement motor cues are necessary for generating grid-specific firing patterns, possibly by driving velocity modulation of theta rhythmicity, which may be used as a speed signal to generate the repeating pattern of grid cells.

Keywords: grid cell; head-direction cell; passive transport; self-movement cues; theta rhythm.

Publication types

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

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Biological Transport
  • Electroencephalography / methods
  • Female
  • Nerve Net / metabolism
  • Nerve Net / physiology
  • Neurons / metabolism
  • Neurons / physiology*
  • Parahippocampal Gyrus / metabolism
  • Parahippocampal Gyrus / physiology*
  • Rats
  • Rats, Long-Evans
  • Space Perception / physiology*
  • Spatial Analysis
  • Theta Rhythm / physiology