Sharply contoured theta waves are the human correlate of ponto-geniculo-occipital waves in the primary visual cortex.
Level 4 - case-series / case-control
Case series of intracranial recordings in epilepsy patients
PubMed 29807231 · doi:10.1016/j.clinph.2018.04.605
What was done
Eleven patients with epilepsy undergoing combined intracranial EEG and polysomnography had 71 channels recording physiological activity across cortical areas, including seven channels in the primary visual cortex. Investigators visually analyzed and compared 4-second segments of phasic versus tonic rapid eye movement (REM) sleep for patterns consistent with ponto-geniculo-occipital (PGO) waves and performed spectral analysis comparing the primary visual cortex to other cortical regions.
What was found
Visual inspection showed an increase in sharply contoured theta waves (duration 150-250 ms) in the primary visual cortex during phasic compared to tonic REM sleep. Classical animal-type PGO wave morphologies were not observed. Spectral analysis demonstrated a 32% increase in mean absolute theta power during phasic versus tonic REM sleep in the primary visual cortex (corrected p = 0.014).
Why it matters
This study provides direct intracranial electrophysiological evidence in humans identifying transient, sharply contoured theta waves in the primary visual cortex as the likely human counterpart to PGO waves established in animal REM sleep models.
Limits
The sample size was very small (11 patients and only 7 channels directly recording primary visual cortex). All participants were patients with epilepsy undergoing invasive monitoring, which may limit generalizability to healthy human sleep physiology. Non-visual pathways and subcortical generators were not directly sampled.
Cited by
- supports During REM sleep, a neural circuit starting in the midbrain signals the lateral geniculate nucleus and primary visual cortex every 90 minutes.