Jumping spiders’ visual system revealed

Scientists have solved one of the toughest problems in spider biology – how the arachnids’ visual system works. An interdisciplinary team from Cornell University have for the first time made recordings of neurons associated with visual perception inside the brain of the Phidippus audax, overcoming a problem unique to the jumping spider. “They are carrying high pressure in their body and whenever you poke them, they explode and die,” said Gil Menda, neurophysiologist and postdoctoral researcher. Researchers realised that if their incision was small enough, the spider’s self-healing properties would close the cut around the hair-sized tungsten recording electrode. Hear the researcher speak about their work and the experiment in action The tiny electrodes used to record brain activity had to be placed in the right location – between the spider’s rear eyes – so Menda carefully poked the spider’s cuticle until he broke the surface and inserted the electrode. Researchers covered certain eyes and leaving other exposed; the microelectrodes recorded bursts of activity from individual neurons when an image of the fly was projected on the screen. The jumping spider has a unique visual system allowing them to use different sets of eyes to process acuity and motion, meaning the spider has to integrate input from different sets of eyes in a nonlinear manner. Menda said these spiders are unique since they deserted the web and their evolution and hunt their prey. They have large eyes – the median – which have almost the same resolution as a human eye but whereas the human eye is responsible for both acuity and movement, this is spread across several eyes in the spider. When one set of eyes was open and another covered, there was little response in the visual processing parts of the brain, the researchers found. However when different sets of eyes were open together, the same image provoked neural activity suggesting the spider needs all its eyes open for the brain to process information. The study provides clues for how a jumping spider’s brain processed information and opens up a new field of basic neuroscience, said Ron Hoy, professor of neurobiology and behaviour. He believes roboticists may be interested in the findings, published in Current Biology, as they aim to develop ever-smaller biosensors.  Visual Perception in the Brain of a Jumping Spider