Delta rhythm in wakefulness: evidence from intracranial recordings in human beings

J Neurophysiol. 2015 Aug;114(2):1248-54. doi: 10.1152/jn.00249.2015. Epub 2015 Jun 17.

Abstract

A widely accepted view is that wakefulness is a state in which the entire cortical mantle is persistently activated, and therefore desynchronized. Consequently, the EEG is dominated by low-amplitude, high-frequency fluctuations. This view is currently under revision because the 1-4 Hz delta rhythm is often evident during "quiet" wakefulness in rodents and nonhuman primates. Here we used intracranial EEG recordings to assess the occurrence of delta rhythm in 18 awake human beings. Our recordings reveal rhythmic delta during wakefulness at 10% of all recording sites. Delta rhythm could be observed in a single cortical lobe or in multiple lobes. Sites with high delta could flip between high and low delta power or could be in a persistently high delta state. Finally, these sites were rarely identified as the sites of seizure onset. Thus rhythmic delta can dominate the background operation and activity of some neocortical circuits in awake human beings.

Keywords: arousal; delta; sleep; wakefulness.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cerebral Cortex / physiology*
  • Cerebral Cortex / physiopathology
  • Cerebral Cortex / surgery
  • Delta Rhythm / physiology*
  • Electrocorticography
  • Electrodes, Implanted
  • Epilepsy / physiopathology
  • Epilepsy / surgery
  • Female
  • Humans
  • Male
  • Middle Aged
  • Seizures / physiopathology
  • Seizures / surgery
  • Wakefulness / physiology*
  • Young Adult