Millennium Post

Rats, cockroaches are wired with GPS!

Like humans, rats and cockroaches appear to have a similar Global Positioning System (GPS) in their heads that allows them to navigate new surroundings, a new study has found.

The finding is likely an example of convergent evolution - that is, distinct animals developed similar systems to manage the same problems.

Further studies on cockroaches may yield new insights into how humans orient themselves and navigate, researchers said. “We’ve known that a mammal can come into a new area and, after a short period of being disoriented, find its way around,” said Roy Ritzmann, a professor at Case Western Reserve University in the US.

Humans and other mammals rely on head-direction, place and grid cells in their brains to process, integrate and update sensory information. The cues come from the direction they look, what they see and motion, he said.

Insects must manoeuvre through new environments, too.

“Orienting contributes to spatial memory, so they can return to point A or navigate to something they like or away from something they don’t like,” said PhD student Adrienn G Varga, lead author of the study.

By repeating experiments that uncovered head-direction cells in rats, researchers found head-direction-like activity and evidence of contextual cue processing in cockroaches.

The researchers recorded cell activities in an area of the brain called the central complex while roaches were restrained in a tube. Each roach was placed on a platform that rotated clockwise or counter clockwise. The platform was encircled by a black wall with a single removable landmark: a white square.

The insects were rotated 360 degrees in 30-degree increments, four to six times, both clockwise and counterclockwise.

Though roaches lack an inner ear, they have a vestibular-like system that provides directional cues.

Similar to humans, who appear to have different cells that fire when turning clockwise compared to counterclockwise, the cell activity in roaches was different when turning clockwise from counterclockwise.

The greatest cell activity came while the white card was inserted in the wall, providing a visual landmark along with cues given by the passive motion from the rotating platform.
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