Neurologists Daniel Winkowski and Eric Knudsen of Stanford University wired 12 owls with electrodes in the areas of their brains that process either visual or auditory input. Each region literally maps the world of sound or sight, determining whether it comes from up or down, left or right. Sending a small electrical charge into the owl's visual brain region--the so-called arcopallial gaze fields--caused it to move its head and eyes in a particular direction. When a simultaneous audio stimulus matched that direction, the owl's brain responded more strongly to that noise. It also blocked out competing noises from other directions.
Owls are already extremely gifted at tuning in a particular sound, the authors note in their paper published in the current issue of Nature, but pairing a sound with a sight enhanced that ability even further. "The ability to hear and the direction of gaze aren't necessarily linked," Winkowski says. But "the circuits in the brain that control gaze direction affect how the brain processes auditory information."
Similar sound-and-vision circuitry has already been demonstrated in monkeys and humans, but the owls represent the first nonprimates to show this."The fundamental mechanisms are probably going to be the same in all vertebrates, as even frogs and fish have gaze control," Knudsen says. "The promise here is that because we are doing this in owls, we can get at the mechanisms of how this works."
The researchers hope to realize that promise by further manipulating the owls' brains to determine the actual neurotransmitters and receptors involved in signaling attention. Ultimately, that could lead to improved performance for humans with attention disorders. "Once we learn the circuitry for attention, we plan to use that to drive learning in an efficient way," Knudsen adds. "If you understand mechanistically how [attention] works, then you will know how best to fix it."