Speed modulation of hippocampal theta frequency correlates with spatial memory performance

Hippocampus. 2013 Dec;23(12):1269-79. doi: 10.1002/hipo.22164. Epub 2013 Aug 5.


Hippocampal theta rhythm is believed to play a critical role in learning and memory. In animal models of temporal lobe epilepsy (TLE), there is evidence that alterations of hippocampal theta oscillations are involved in the cognitive impairments observed in this model. However, hippocampal theta frequency and amplitude at both the local field potential (LFP) and single unit level are strongly modulated by running speed, suggesting that the integration of locomotor information into memory processes may also be critical for hippocampal processing. Here, we investigate whether hippocampal speed-theta integration influences spatial memory and whether it could account for the memory deficits observed in TLE rats. LFPs were recorded in both Control (CTR) and TLE rats as they were trained in a spatial alternation task. TLE rats required more training sessions to perform the task at CTR levels. Both theta frequency and power were significantly lower in the TLE group. In addition, speed/theta frequency correlation coefficients and regression slopes varied from session to session and were worse in TLE. Importantly, there was a strong relationship between speed/theta frequency parameters and performance. Our analyses reveal that speed/theta frequency correlation with performance cannot merely be explained by the direct influence of speed on behavior. Therefore, variations in the coordination of theta frequency with speed may participate in learning and memory processes. Impairments of this function could explain at least partially memory deficits in epilepsy.

Keywords: Hippocampus; epilepsy; local field potentials; spatial alternation; theta rhythm.

Publication types

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

MeSH terms

  • Animals
  • Disease Models, Animal
  • Electrodes, Implanted
  • Electroencephalography
  • Epilepsy, Temporal Lobe / chemically induced
  • Epilepsy, Temporal Lobe / complications
  • Food Deprivation
  • Hippocampus / physiopathology*
  • Lithium Chloride / toxicity
  • Maze Learning / drug effects
  • Maze Learning / physiology
  • Memory Disorders / etiology
  • Memory Disorders / pathology*
  • Muscarinic Agonists / toxicity
  • Pilocarpine / toxicity
  • Rats
  • Rats, Sprague-Dawley
  • Space Perception / drug effects
  • Space Perception / physiology*
  • Theta Rhythm / drug effects
  • Theta Rhythm / physiology*
  • Time Factors


  • Muscarinic Agonists
  • Pilocarpine
  • Lithium Chloride