Brain oscillatory 4-30 Hz responses during a visual n-back memory task with varying memory load

Brain Res. 2007 Mar 23;1138:171-7. doi: 10.1016/j.brainres.2006.12.076. Epub 2007 Jan 4.


Brain oscillatory responses of 4-30 Hz EEG frequencies elicited during the performance of a visual n-back task were examined in 36 adult volunteers. Event-related desynchronization (ERD) and event-related synchronization (ERS) responses were examined separately for targets and non-targets in four different memory load conditions (0-, 1-, 2- and 3-back). The presentation of all stimuli in all memory load conditions elicited long-lasting theta frequency (approximately 4-6 Hz) ERS responses which were of greater magnitude for the target stimuli as compared to the non-target stimuli. Alpha frequency range (approximately 8-12 Hz) ERD responses were observed in all memory load conditions for both targets and non-targets. The duration of these alpha ERD responses increased with increasing memory load and reaction time. In all memory load conditions, early appearing beta rhythm (approximately 14-30 Hz) ERD responses were elicited, and with increasing memory load, these beta ERD responses became longer in duration. Additionally, beta ERS responses were observed in the 0- and 1-back memory load conditions. The current results reveal a complex interplay between brain oscillations at different frequencies during a cognitive task performance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alpha Rhythm
  • Brain / physiology*
  • Cortical Synchronization
  • Electroencephalography*
  • Humans
  • Male
  • Memory / physiology*
  • Photic Stimulation
  • Reaction Time
  • Theta Rhythm
  • Visual Perception / physiology*