Thomas P. Bleck tpb9k at galen.med.Virginia.EDU
Wed Jul 27 08:01:02 EST 1994

In article <CtJvIo.FJ9 at murdoch.acc.Virginia.EDU>,
Adam Stephen Arthur <asa3h at galen.med.Virginia writes:

>I ran across an interesting thing about dolphin brains last
>year.  Appparently their two hemispheres are alternately
>active.  The original reference was (if I remember correctly)
>in Penrose's "The Emperor's New Mind" but I ran it down and
>found it quite fascinating.  EEG recordings showed delta wave
>patterns in one hemisphere (sleep?) while the other was active
>and vice versa.  The supposition was that since they are
>aquatic mammals, this was a mechanism to keep them moving at
>all times; the organism as a whole never slept.  The
>possible implications for human hemisphericity are interesting.

I believe that killer whales have also been monitored and show the same
hemispheric switching (I heard the paper at a meeting but don't recall
seeing it in print.

A variant explanation is that these mammals have completely voluntary
respiration; the animal would not breathe if both hemispheres were
Tom Bleck    (Thomas P. Bleck, M.D.)   tbleck at virginia.edu
Departments of Neurology and Neurological Surgery
University of Virginia School of Medicine

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