Naked Mole-Rats

Naked mole-rats (Heterocephalus glaber) are remarkabe rodents that live underground in Africa.  They are “eusocial” – living in colonies with a single breeding female, a few male drones, and non-reproductive workers.  They have small eyes and ears but a keen sense of touch.  Their bodies are covered with small sensory hairs used for orienting in dark tunnels.
Naked mole-rat neocortex is dominated by the somatosensory area (S1).  This large map of the contralateral body surface takes up a much greater proportion of the neocortex in mole-rats than is the case for other rodents.  The area typically devoted to vision in mammals is occupied by part of the somatosensory map (PDF of Paper).


The “moleratunculus” illustrated to the left shows the proportions of body parts as represented in the mole-rat brain.  A surprisingly large area of the somatosensory map is devoted to the front teeth.  Mole-rats use their teeth to dig extensive tunnels and for manipulating objects, making the incisors an important sensory structure (drawing by Lana Finch).
When a new queen takes over the colony and begins to reproduce, her spinal column lengthens to accommodate an expanded reproductive tract and large litters of young (sometimes 20 or more embryos).  X-rays of transitioning queens (right) show that most of this bone growth occurs during pregancies (PDF of Paper).


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