The visual system in subterranean African mole-rats (Rodentia, Bathyergidae): Retina, subcortical visual nuclei and primary visual cortex

Němec, Pavel; Cveková, Pavla; Benada, Oldřich; Wielkopolska, Ewa; Olkowicz, Seweryn; Turlejski, K; Burda, Hynek; Bennett, Nigel C.; Peichl, Leo

doi:10.1016/j.brainresbull.2007.10.055

Cited by 65 publications

(94 citation statements)

References 37 publications

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“…The ventral half-retina receives light from the upper visual field, and an increased S cone density may allow the mole to have a better perception of breaches in their tunnel network. A possible role of the visual systems in antipredatory behaviour has been previously suggested for subterranean rodents (Němec et al 2007(Němec et al , 2008.…”

Section: (B) Differentiation Of the Iberian Mole Retinamentioning

confidence: 99%

Retinal development and function in a ‘blind’ mole

Carmona

Glösmann

et al. 2009

Proc. R. Soc. B.

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Animals adapted to dark ecotopes may experience selective pressure for retinal reduction. No previous studies have explicitly addressed the molecular basis of retinal development in any fossorial mammal. We studied retinal development and function in the Iberian mole Talpa occidentalis, which was presumed to be blind because of its permanently closed eyes. Prenatal retina development was relatively normal, with specification of all cell types and evidence of dorsoventral regionalization. Severe developmental defects occurred after birth, subsequent to lens abnormalities. 'Blind' Iberian moles had rods, cones and rod nuclear ultrastructure typical of diurnal mammals. DiI staining revealed only contralateral projections through the optic chiasm. Y-maze experiments demonstrated that moles retain a photoavoidance response. Over-representation of melanopsin-positive retinal ganglion cells that mediate photoperiodicity was observed. Hence, molecular pathways of eye development in Iberian moles retain the adaptive function of rod/cone primary vision and photoperiodicity, with no evidence that moles are likely to completely lose their eyes on an evolutionary time scale.

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Section: (B) Differentiation Of the Iberian Mole Retinamentioning

confidence: 99%

Retinal development and function in a ‘blind’ mole

Carmona

Glösmann

et al. 2009

Proc. R. Soc. B.

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“…In a dark world deprived of most of the sensory cues that are normally available aboveground, the Earth's magnetic field provides the only reliable and omnipresent source of directional information. Indeed, the strictly subterranean mode of life has resulted in a decreased reliance on vision associated with microphthalmia and a severely reduced visual system that is poorly equipped for visually guided navigation Nemec et al, 2008). Thus, magnetic cues likely enable subterranean dwellers to orientate when digging long tunnels, to interconnect damaged tunnels, to bypass effectively obstacles, and possibly to find their way back home after rare surface activities (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…African molerat eyes feature normal properties, indicating the capability of imageforming vision (Cernuda-Cernuda et al, 2003;Peichl et al, 2004). However, their object vision is constrained by extremely low visual acuity (Nemec et al, 2008) and severe regression of the visual domains involved in the coordination of the visuomotor reflexes important for the stabilization of the image on the retina . Therefore, the microphthalmia and regressed visual system may hypothetically impair the light-dependent magnetic compass in these strictly subterranean rodents and possibly other microphthalmic mammals such as echolocating bats, provided that it prevents the perception of contours.…”

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confidence: 99%

Magnetic compass orientation in two strictly subterranean rodents: learned or species-specific innate directional preference?

Oliveriusová

Němec

Králová

et al. 2012

Journal of Experimental Biology

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SUMMARYEvidence for magnetoreception in mammals remains limited. Magnetic compass orientation or magnetic alignment has been conclusively demonstrated in only a handful of mammalian species. The functional properties and underlying mechanisms have been most thoroughly characterized in Ansellʼs mole-rat, Fukomys anselli, which is the species of choice due to its spontaneous drive to construct nests in the southeastern sector of a circular arena using the magnetic field azimuth as the primary orientation cue. Because of the remarkable consistency between experiments, it is generally believed that this directional preference is innate. To test the hypothesis that spontaneous southeastern directional preference is a shared, ancestral feature of all African mole-rats (Bathyergidae, Rodentia), we employed the same arena assay to study magnetic orientation in two other mole-rat species, the social giant mole-rat, Fukomys mechowii, and the solitary silvery mole-rat, Heliophobius argenteocinereus. Both species exhibited spontaneous western directional preference and deflected their directional preference according to shifts in the direction of magnetic north, clearly indicating that they were deriving directional information from the magnetic field. Because all of the experiments were performed in total darkness, our results strongly suggest that all African mole-rats use a lightindependent magnetic compass for near-space orientation. However, the spontaneous directional preference is not common and may be either innate (but species-specific) or learned. We propose an experiment that should be performed to distinguish between these two alternatives.Supplementary material available online at

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“…It should be noted that Ansel"s and Damaraland mole rats were previously considered to be members of the genus Cryptomys. All three species of mole rat have a reduced visual system, live a subterranean lifestyle and have unusual patterns of circadian rhythmicity (Lovegrove and Papenfus, 1995;Lovegrove and Muir, 1996;Oelschlager et al, 2000;Cernuda-Cernuda et al, 2003;Negroni et al, 2003;Oosthuizen et al, 2003;Gutjahr et al, 2004;Nemec et al, 2004;Nemec et al, 2008). Brains from circadian distinct rhythmic and arrhythmic individuals of each species were examined.…”

Section: Introductionmentioning

confidence: 99%

Orexinergic neuron numbers in three species of African mole rats with rhythmic and arrhythmic chronotypes

Bhagwandin¹,

Gravett²,

Hemingway³

et al. 2011

Neuroscience

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In the present study orexinergic cell bodies within the brains of rhythmic and arrhythmic circadian chronotypes from three species of African mole rat (Highveld mole ratCryptomys hottentotus pretoriae, Ansel"s mole rat -Fukomys anselli and the Damaraland mole rat -Fukomys damarensis) were identified using immunohistochemistry for orexin-A.Immunopositive orexinergic (Orx+) cell bodies were stereologically assessed and absolute numbers of orexinergic cell bodies were determined for the distinct circadian chronotypes of each species of mole rat examined. The aim of the study was to investigate whether the absolute numbers of identified orexinergic neurons differs between distinct circadian chronotypes with the hypothesis of elevated hypothalamic orexinergic neurons in the arrhythmic chronotypes compared to the rhythmic chronotypes. We found statistically significant differences between the circadian chronotypes of F. anselli, where the arrhythmic group had higher mean numbers of hypothalamic orexin neurons compared to the rhythmic group. These differences were observed when the raw data was compared and when the raw data was corrected for body mass (M b ) and brain mass (M br ). For the two other species investigated no significant differences were noted between the chronotypes, although a statistically significant difference was noted between all rhythmic and arrhythmic individuals of the current study when the counts of orexin neurons were corrected for M b -the arrhythmic individuals had larger numbers of orexin cells.

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The visual system in subterranean African mole-rats (Rodentia, Bathyergidae): Retina, subcortical visual nuclei and primary visual cortex

Cited by 65 publications

References 37 publications

Retinal development and function in a ‘blind’ mole

Retinal development and function in a ‘blind’ mole

Magnetic compass orientation in two strictly subterranean rodents: learned or species-specific innate directional preference?

Orexinergic neuron numbers in three species of African mole rats with rhythmic and arrhythmic chronotypes

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