K-Complex

The K-complex is a waveform pattern observed in electroencephalography (EEG) signals during sleep. It is characterized by a distinct and sharp negative deflection followed by a slower positive component. K-complexes are most commonly observed in stage 2 of non-rapid eye movement (NREM) sleep.

Properties of K-Complex:

  • Shape: K-complexes have a distinct and well-defined shape characterized by a sharp negative deflection (downward waveform) followed by a slower positive deflection (upward waveform).
  • Duration: The duration of a K-complex typically ranges from half a second to several seconds.
  • Amplitude: The amplitude of a K-complex is usually large, with a peak-to-peak amplitude often exceeding 75 microvolts.
  • Location: K-complexes predominantly occur in the frontal and central regions of the brain, as observed on scalp EEG recordings.

Functions of K-Complex:

The precise functions of K-complexes are still not fully understood, but they are believed to serve several purposes during sleep:

  1. Sleep protection: K-complexes are thought to act as a mechanism to protect sleep integrity by suppressing external stimuli that might disrupt sleep.
  2. Memory consolidation: Studies suggest that K-complexes play a role in memory consolidation, particularly in the transfer of information from short-term to long-term memory.
  3. Brain plasticity: K-complexes are also believed to be involved in neural plasticity processes, contributing to the reorganization and strengthening of synaptic connections in the brain.

Although K-complexes are most commonly associated with stage 2 NREM sleep, they can also occur during other sleep stages, such as stage 3 and 4 NREM sleep, as well as in certain pathological conditions.