November 5, 2011

Hippocampus (or should I say, elephant-campus)

I am always in awe of "unlikely animal friends," and there are plenty of these videos on YouTube from which to enjoy. This CBS Evening News Assignment America particularly interested me:

Steve Hartman has reported two follow-ups since this 2009 feature about an unlikely friendship between Tarra the elephant and Bella the dog. The latest, which I caught when aired two nights ago, was heartbreaking, but extraordinarily fascinating. Sadly, Bella was killed by what appeared to be a coyote attack on October 26. When the location of the attack was pinpointed, the blood on Tarra's trunk made it evident that the elephant had carried her friend a mile back to the house. Tarra is now showing all the signs of depression—her fellow elephant friends at the Elephant Sanctuary in Hohenwald, TN have been reaching out to her, spending more time with her and offering her their food. Nothing short of amazing, right?

Anybody with a pet wonders whether their animals can feel emotion. Scientific studies have reported signs of joy in rats, empathy in mice, and anger in baboons. We've all heard about pets who stand vigil over sick or dying owners, dogs who adopt extreme levels of responsibility for the blind or disabled, and my friend has a cat who is particularly affectionate when she isn't feeling well, physically or emotionally.

Elephants, in particular, demonstrate unusually high levels of grief in response to tragedy. They have also been shown to suffer psychological flashbacks resembling post-traumatic stress disorder (PTSD), and their wide range of human-like behaviors include mimicry, art, play, altruism, use of tools, problem-solving, cooperation, a sense of humor, and possibly language.

Elephants, it turns out, have an unusually large and convoluted hippocampus, a region in the brain particularly involved in emotion. In elephants, the hippocampus comprises 0.7% of the central structure of the brain, compared to just 0.5% in humans and 0.1% in dolphins, another highly intelligent and emotional mammal. Memory is stored in the temporal lobe (structure 1a, left), which is especially large and distinct in the elephant. Their particularly developed spatial memory may account for their tendency toward flashbacks and incredible ability to traverse long distances by memory.

All very fascinating, but in the meantime, makes a sad story for Tarra and her lost friend. It seems that Aristotle was correct in once noting that elephants are "the beast which passeth all others in wit and mind."

Video courtesy CBS. Photos courtesy Wikipedia and Max Waugh.

Hakeem, A., Hof, P., Sherwood, C., Switzer, R., Rasmussen, L., & Allman, J. (2005). Brain of the African elephant (Loxodonta africana): Neuroanatomy from magnetic resonance images The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology, 287A (1), 1117-1127 DOI: 10.1002/ar.a.20255

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