Memory encoding-related anterior hippocampal potentials are modulated by deep brain stimulation of the entorhinal area

Research output: Contribution to journalArticlepeer-review


  • Niels Hansen
  • Leila Chaieb
  • Marlene Derner
  • Kevin G. Hampel
  • Christian E. Elger
  • Rainer Surges
  • Nikolai Axmacher
  • Juergen Fell

External organisations

  • University of Bonn
  • Universitat Bochum


Background: Deep brain stimulation (DBS) of the human entorhinal area using 50 Hz pulses has revealed conflicting results regarding memory performance. Moreover, its impact on memory-related hippocampal potentials has not yet been investigated. 

Methods: We recorded data from seven epilepsy patients implanted with depth electrodes in the entorhinal cortex, hippocampus, amygdala, and parahippocampal cortex. Entorhinal DBS (bipolar, biphasic 50 Hz pulses, on- and off-cycles of 15 s) was applied with low amplitude (0.1 mA) to resemble physiologic conditions. During DBS on- and off-periods, patients learned noun-color associations that were later tested. 

Results: During entorhinal DBS we observed more positive deflections of event-related potentials (ranging from 700 to 950 ms) in the anterior hippocampus for the on- vs. off-condition. We detected no effects in the amygdala, mid hippocampus and parahippocampal cortex. On the behavioral level, no differences in memory performance (item and source memory) were apparent in the on- vs. off-condition, neither across all trials nor across patients. 

Discussion: Our findings indicate that entorhinal DBS with low amplitude has an impact on memory encoding-related potentials within the anterior hippocampus, but not on memory performance per se.


Original languageEnglish
Pages (from-to)12-17
Number of pages6
Issue number1
Early online date30 Oct 2017
Publication statusPublished - 1 Jan 2018


  • anterior hippocampus, associative memory, deep brain stimulation, entorhinal area, event-related potentials

ASJC Scopus subject areas