Delta brainwave

The effects of the absence of the Delta Brainwave in Fry.

The Delta Brainwave is generated by all animals (with the exception of Philip J. Fry, due to him being his own grandfather), all robots, and certain trees. The Brain Spawn attack the Delta Brainwave.

The Legion of Mad Fellows are able to read people's thoughts from their Delta Brainwave.

It is possible that the Brain Slugs feed on Delta Brainwave.

Additional Info

Mentions

Since the Delta Brainwave is generated by every character but Fry, it is technically present in every episode (as there is at least one more character in every episode).

• "The Day the Earth Stood Stupid" (3ACV07)
  
• "The Cyber House Rules" (3ACV09)
  
  (possibly)
• "The Why of Fry" (4ACV10)
  
• Into the Wild Green Yonder