1. Foraging in moles, bees, and birds

2. Star nosed mole, eastern mole, African hedgehog, and masked shrew (bottom right).

3. Star-nosed mole Lives in wet, marshy soil
Burrowing habitat in dark tunnels
Eats earthworms and other prey
Eyes are greatly reduced and even in light, visual information is not prioritized
Uses sense of touch to find food and navigate

4. Goal: use the star-nosed mole as a model to understand cognitive representations of sensory space

5. Eimer’s organs are mechanoreceptors
Eimer’s organs are mechanoreceptors. Respond to deformation of the membrane, probably by opening of stretch sensitive ion channels that depolarize the neuron.
Most highly innervated organ in nature. Smallest receptive fields known.

6. Detection of an object by any appendage stimulates the appropriate head adjustment so the object can be sampled by appendage 11. A disproportionate number of nerve fibers send information from appendage 11 to the brain than any other. Sensory bias is matched by cortical bias in somatosensory cortex, where 25% of the ss cortex devoted to the nose is responsible for analyzing information from appendage 11.

7. Cortical magnification reflects adaptive sensory biases

8. Figure 3. Transcriptome profiling of mole trigeminal and dorsal root ganglia.
Green=TG higher, Grey=DRG higher
What are the cellular and molecular building blocks that enable this great touch sensitivity in the star?
Gerhold KA, Pellegrino M, Tsunozaki M, Morita T, et al. (2013) The Star-Nosed Mole Reveals Clues to the Molecular Basis of Mammalian Touch. PLoS ONE 8(1): e doi: /journal.pone

9. Figure 5. Expression of candidate transducers in mouse ganglia.
Conservation of mole identified target genes in mouse TG (easier to study function in mice)
Gerhold KA, Pellegrino M, Tsunozaki M, Morita T, et al. (2013) The Star-Nosed Mole Reveals Clues to the Molecular Basis of Mammalian Touch. PLoS ONE 8(1): e doi: /journal.pone

10. Figure 2. Functional enrichment of light touch-sensitive neurons in the star-nosed mole trigeminal ganglia.
A fura-2 calcium dye shows that TG innervating the star nose has greater responses to touch (stretch) than the DRG, which innervates the rest of the body sensation
Both respond the painful capsaicin with increases in calcium
B. A greater proportion of TG neurons respond to touch stimuli than painful stimuli, and than DRG neurons.
Conclude, the TG relays the touch information of the star nose, while the DRG may process touch info from other places on the body
Gerhold KA, Pellegrino M, Tsunozaki M, Morita T, et al. (2013) The Star-Nosed Mole Reveals Clues to the Molecular Basis of Mammalian Touch. PLoS ONE 8(1): e doi: /journal.pone

11. Food storage in birds
While some species find food and consume it immediately, others store their cache for days, weeks, or months at a time
Jays
Some use a sticky saliva to cement their cached items to a tree crevice
Nuthatches
Hoarders able to find more seeds than naïve birds
Clark’s nutcrackers
Size of the seed
May cache 100,000 seeds in the fall
Tufted titmouse does not hoard but can watch a nuthatch hide a seed, then steal it

12. Individual birds seeds recovered,, storers vs non--storers

14. Individual differences
Climate is more harsh and demanding in Alaska; black capped chickadees there are better at finding hidden food
Hippocampal size?

15. NON-STORER
STORER
Log HIPPOCAMPAL VOLUME (mm3)
BODY WEIGHT
Krebs et al 1996

16. Learned differences
Experiment in lab raised birds examined environmental contributions to hippocampal development
Birds were given full seeds to eat or hide or powdered seeds to eat
Birds given full seeds had more cells in their hippocampus than the birds denied a food storing experience.

17. Seed storing modifies hippocampal volume
Sperry 2007

18. Depends on experience
Clayton, 1998