Rapid eye movement sleep resemblance to waking life), and incorporation of instinctual themes. Sometimes they include elements of the dreamer's recent experience taken directly from episodic memory. By one estimate, 80% of dreams occur during REM. Hobson and McCarley proposed that the PGO waves characteristic of “phasic” REM might supply the visual cortex and forebrain with electrical excitement which amplifies the hallucinatory aspects of dreaming. However, people woken up during sleep do not report significantly more bizarre dreams during phasic REMS, compared to tonic REMS. Another possible relationship between the two phenomena could be that the higher threshold for sensory interruption during REM sleep
PGO waves and subthalamic nucleus (or subthalamus). This latter, glutamatergic nucleus is reciprocally connected with the PGO-transferring nuclei of the pons. In humans, subthalamic PGO-like waves, that resemble the PGO waves typically recorded in cats, can be recorded during pre-REM and REM sleep. This suggests that the subthalamus may play an active role in an ascending activating network implicated in the rostral transmission of PGO waves during REM sleep in humans. PGO waves are an integral part of rapid eye movement (REM) sleep. As stated earlier, the density of the PGO waves coincides with the amount of eye movement measured in REM