title: Passive Transport Disrupts Grid Signals in the Parahippocampal Cortex.
abstract: 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.
authors.affiliation: Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH 03755, USA. Electronic address: shawn.s.winter@dartmouth.edu.
authors.forename: Shawn S
authors.initials: SS
authors.lastname: Winter
authors.affiliation: Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Max L
authors.initials: ML
authors.lastname: Mehlman
authors.affiliation: Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Clark
authors.affiliation: Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH 03755, USA. Electronic address: jeffrey.taube@dartmouth.edu.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Taube
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001692:Biological Transport; D004569:Electroencephalography / Q000379:methods; D005260:Female; D009415:Nerve Net / Q000378:metabolism / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D020534:Parahippocampal Gyrus / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D013028:Space Perception / Q000502:physiology*; D062206:Spatial Analysis; D013826:Theta Rhythm / Q000502:physiology
keywords: grid cell; head-direction cell; passive transport; self-movement cues; theta rhythm