Article abstract

Nature Neuroscience 10, 224 - 233 (2007)
Published online: 7 January 2007 | doi:10.1038/nn1829

Hippocampal cellular and network activity in freely moving echolocating bats

Nachum Ulanovsky1,2 & Cynthia F Moss1,2,3

The hippocampus is crucial for episodic and spatial memory. In freely moving rodents, hippocampal pyramidal neurons show spatially selective firing when the animal passes through a neuron's 'place-field', and theta-band oscillation is continuously present during locomotion. Here we report the first hippocampal recordings from echolocating bats, mammals phylogenetically distant from rodents, which showed place cells very similar to those of rodents. High-frequency 'ripple' oscillations were also rodent-like. Theta oscillation, however, differed from rodents in two important ways: (i) theta occurred when bats explored the environment without locomoting, using distal sensing through echolocation, and (ii) theta was not continuous, but occurred in short intermittent bouts. The intermittence of theta suggests that models of hippocampal function that rely on continuous theta may not apply to bats. Our data support the hypothesis that theta oscillation in the mammalian hippocampus is involved in sequence learning and hence, theta power should increase with sensory-input rate—which explains why theta power correlates with running speed in rodents and with echolocation call rate in bats.

  1. Department of Psychology, University of Maryland, College Park, Maryland 20742, USA.
  2. Institute for Systems Research, University of Maryland, College Park, Maryland 20742, USA.
  3. Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland 20742, USA.

Correspondence to: Nachum Ulanovsky1,2 e-mail:


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