Data from: Functional MRI in the Nile crocodile: a new avenue for evolutionary neurobiology

Crocodilians are important for understanding the evolutionary history of
amniote neural systems as they are the nearest extant relatives of modern
birds and share a stem amniote ancestor with mammals. Although the
crocodilian brain has been investigated anatomically, functional studies
are rare. Here we employed fMRI, never tested in poikilotherms, to
investigate crocodilian telencephalic sensory processing. Juvenile
Crocodylus niloticus were placed in a 7T MRI scanner to record BOLD signal
changes during presentation of visual as well as auditory stimuli. Visual
stimulation increased BOLD signals in rostral to mid-caudal portions of
the dorso-lateral anterior dorsal ventricular ridge (ADVR). Simple
auditory stimuli led to signal increase in the rostromedial and
caudocentral ADVR. These activation patterns are in line with previously
described projection fields of diencephalic sensory fibers. Furthermore,
complex auditory stimuli activated additional regions of the caudomedial
ADVR. The recruitment of these additional, presumably higher-order,
sensory areas reflect observations made in birds and mammals. Our results
indicate that structural and functional aspects of sensory processing have
been likely conserved during the evolution of sauropsids. In addition, our
study shows that fMRI can be utilized to investigate neural processing in
poikilotherms, providing a new avenue for neurobiological research in
these critical species.