[MARMAM] New publication on killer whale neuroanatomy

Alexandra Wright alexandrakwright at gmail.com
Thu Apr 28 18:05:45 PDT 2016

Hello MarMam community,

We are pleased to announce our new publication on killer whale neuroanatomy
in *Brain Structure and Function*:

*Wright A, Scadeng M, Stec D, Dubowitz R, Ridgway S, St. Leger J. 2016.
Neuroanatomy of the killer whale (Orcinus orca): a magnetic resonance
imaging investigation of structure with insights on function and evolution.
Brain Struct Funct. 1–20.*

*Abstract:* The evolutionary process of adaptation to an obligatory aquatic
existence dramatically modified cetacean brain structure and function. The
brain of the killer whale (*Orcinus orca*) may be the largest of all taxa
supporting a panoply of cognitive, sensory, and sensorimotor abilities.
Despite this, examination of the *O. orca* brain has been limited in scope
resulting in significant deficits in knowledge concerning its structure and
function. The present study aims to describe the neural organization and
potential function of the *O. orca* brain while linking these traits to
potential evolutionary drivers. Magnetic resonance imaging was used for
volumetric analysis and three-dimensional reconstruction of an in situ
postmortem *O. orca* brain. Measurements were determined for cortical gray
and cerebral white matter, subcortical nuclei, cerebellar gray and white
matter, corpus callosum, hippocampi, superior and inferior colliculi, and
neuroendocrine structures. With cerebral volume comprising 81.51 % of the
total brain volume, this *O. orca* brain is one of the most corticalized
mammalian brains studied to date. *O. orca* and other delphinoid cetaceans
exhibit isometric scaling of cerebral white matter with increasing brain
size, a trait that violates an otherwise evolutionarily conserved cerebral
scaling law. Using comparative neurobiology, it is argued that the
divergent cerebral morphology of delphinoid cetaceans compared to other
mammalian taxa may have evolved in response to the sensorimotor demands of
the aquatic environment. Furthermore, selective pressures associated with
the evolution of echolocation and unihemispheric sleep are implicated in
substructure morphology and function. This neuroanatomical dataset,
heretofore absent from the literature, provides important quantitative data
to test hypotheses regarding brain structure, function, and evolution
within Cetacea and across Mammalia.

The publication is available online (
http://link.springer.com/article/10.1007/s00429-016-1225-x) or by request (
awright at ucsd.edu *or* alexandrakwright at gmail.com)

Kind regards,

Alexandra Wright
*Alexandra Wright*, PhD candidate
Center for Marine Biotechnology & Biomedicine
Scripps Institution of Oceanography, UCSD
awright at ucsd.edu or alexandrakwright at gmail.com
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