Compartmentation of the Cerebellar Cortex in the Naked Mole-Rat (Heterocephalus glaber)

Abstract

Despite the apparent uniformity in cellular composition of the adult mammalian cerebellar cortex, it is actually highly compartmentalized into transverse zones and within each zone further subdivided into a reproducible array of parasagittal stripes. This basic cerebellar architecture is highly conserved in birds and mammals. However, different species have very different cerebellar morphologies, and it is unclear if cerebellar architecture reflects taxonomic relations or ecological niches. To explore this, we have examined the cerebellum of the naked mole-rat Heterocephalus glaber, a burrowing rodent with adaptations to a subterranean life that include only a rudimentary visual system. The cerebellum of H. glaber resembles that of other rodents with the remarkable exception that cerebellar regions that are prominent in the handling of visual information (the central zone, nodular zone, and dorsal paraflocculus) are greatly reduced or absent. In addition, there is a notable increase in size in the posterior zone, consistent with an expanded role for the trigeminal somatosensory system. These data suggest that cerebellar architecture may be substantially modified to serve a particular ecological niche.

Cerebellar Zones: History, Development, and Function

“…The issue of function is front and center in the second Hawkes paper. In that study, they have examined the transverse and sagittal zone patterns using zebrin II expression in the naked mole rat, a species adapted to life entirely in the dark [33]. These animals have extremely small eyes and retinas, much reduced superior colliculi and lateral geniculate nuclei, and small olivary pretectal nuclei relative to other species, and based on zebrin II expression in the cerebellum, they appear to be largely lacking the central and nodular transverse zones, which is argued to reflect reduced visual processing.…”

Sperm Whales and Killer Whales with the Largest Brains of All Toothed Whales Show Extreme Differences in Cerebellum

“…Differences in cerebellar size between species can reflect differences in ability and function [Putnam, 1927;Sultan and Glickstein, 2007;Marzban et al, 2011]. As the sensorimotor role of the cerebellum is well established [Gao et al, 1996;D'Angelo, 2011], we suggest that the larger cerebellum in the KW may be related to its more active vision and visuomotor skills, its wider range of sound production, and its hunting activities with more types of prey.…”

“…For example, echolocating cetaceans and microchiropteran bats are thought to have a large cerebellum due to enlarged auditory-associated cerebellar areas [Maseko et al, 2012;Hanson et al, 2013]. Similarly, reduced sensory input, as exemplified by visual limitations in the naked mole rat, can lead to a reduced cerebellar size [Marzban et al, 2011]. It is therefore intriguing that there is such a discrepancy in cerebellar size between the KW Marino et al, 2000] and Globicephala and Grampus [from Ridgway and Brownson, 1984].…”

“…The cerebellum receives considerable input from the visual system [Sultan and Glickstein, 2007;Marzban et al, 2011]. In the naked mole rat, a species that is effectively blind, the cerebellum is small compared to other rodents due to less visual stimulation [Marzban et al, 2011].…”

“…In the naked mole rat, a species that is effectively blind, the cerebellum is small compared to other rodents due to less visual stimulation [Marzban et al, 2011]. There is also evidence that SWs might have limited vision.…”