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It is known that dolphins have the ability to sleep with only one half of their brain at a time.

According to this popular science source:

Dolphins sleep by resting one half of their brain at a time. This is called unihemispheric sleep. The brain waves of captive dolphins that are sleeping show that one side of the dolphin's brain "awake" while the other in a deep sleep ("slow-wave sleep"). Also, during this time, one eye is open (the eye opposite the sleeping half of the brain) while the other is closed.

Given that the dolphin probably depends on bilateral brainstem mechanisms for respiration, my assumption is that this "shutting down" mainly involves the cortex.

  • Is this true, or are areas like the thalamus also suppressed unilaterally?
  • How is this "switching" (from hemisphere to hemisphere) managed? Is it accomplished at the level of the thalamus, or within the brainstem?
  • Were a dolphin to be dominant in one hemisphere (surely Flipper was "right-finned"?), how is the representation of the dominant side of the body managed when the opposite cortex is suppressed?
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