Extinct Tasmanian tiger’s brain reconstructed

Melbourne, January 23

Scientists have, for the first time, used an imaging technique to reconstruct the brain architecture and neural networks of the iconic Tasmanian tiger — an extinct carnivorous marsupial native to Tasmania.

The study used magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to scan postmortem specimens of two Tasmanian tiger or thylacine brain specimens, both of which were about 100 years old.

The results, when compared to the Tasmanian tiger’s closest living relative, the Tasmanian devil, suggest that the larger-brained thylacine had more cortex devoted to planning and decision-making.

“The natural behaviour of the thylacine was never scientifically documented,” said Gregory Berns, neuroscientist at Emory University in the US.

“Our reconstruction of its white matter tracts, or neural wiring, between different regions of its brain is consistent with anecdotal evidence that the thylacine occupied a more complex, predatory ecological niche versus the scavenging niche of the Tasmanian devil,” said Berns.

The comparative study also supports theories of brain evolution suggesting that as brains grow larger they become more modular or divided into sections associated with discrete functions, said Berns.

“The technology for imaging the preserved brains of rare, extinct and endangered species is an exciting innovation in the study of brain evolution,” said Kenneth Ashwell from the University of New South Wales in Australia.

“It will allow us to track pathways and study functional connections that could never be analysed through older experimental techniques,” said Ashwell.

The Tasmanian tiger looked like an amalgam of several animals. It is one of only a few marsupials to have a pouch in both sexes.

It was the size and shape of a medium-to-large size dog, but had tiger-like stripes running down its lower back and an abdominal pouch.

The fossil record shows that the Tasmanian tiger appeared about four million years ago in Australia. By the 20th century it was extinct, or extremely rare, on the mainland but was still found in Tasmania, the island state off Australia’s southern coast.

Its demise is attributed to loss of habitat through farming activity, coupled with a bounty scheme placed on the animal after it was suspected of killing sheep and other livestock. The last known Tasmanian tiger died in 1936, in Tasmania’s Hobart Zoo.

The study was published in the journal PLOS ONE. — PTI