Reaching for something, such as a cup of coffee, or to stroke your pet, is a complex neurological process that requires finely orchestrated timing and coordination. A recent study has a team of researchers at New York University’s Center for Neural Science shedding new light on the maneuvering called “gaze anchoring” – a transient stoppage of eye movements required to coordinate the process of reaching.
“Our results show that we anchor our gaze to the target of the reach movement, thereby looking at that target for longer periods,” explains Bijan Pesaran, a professor at NYU, in a statement. “This is what makes our reaches much more accurate. The big question has been: How does the brain orchestrate this kind of natural behavior?”
The study, conducted with Maureen Hagan, a neuroscientist at Australia’s Monash University, explores the elusive process of gaze anchoring—especially how different regions of the brain communicate with each other.
The scientists studied activity in the arm and eye movement regions of the brain. Simultaneously, they studied eye and arm movements in non-human primates.
The first movement was a coordinated look-and-reach to a target. Just 10 milliseconds later, a second target was presented, which subjects needed to look at as quickly as possible. The second eye movement demonstrates the gaze anchoring effect. The movements resemble the type made when changing the radio while driving, while also looking for a street address—if you quickly look away from the radio to the numbers on buildings, you might not select the right channel.
The investigation showed that, during gaze anchoring, neurons are activated in the parietal region of the brain, used for reaching, while inhibiting neurons in the parietal saccade region, used for eye movements. The neurons firing inhibit eye movement, keeping eyes centered on the target of the reach. The process enhances the accuracy of the grasp. Importantly, the scientists note, the effects were tied to patterns of brain waves at 15-25 Hz, called beta waves, that organize neural firing across different regions of the brain.
“Beta waves have been previously linked to attention and cognition, and this study reveals how beta activity may control inhibitory brain mechanisms to coordinate our natural behavior,” explains Pesaran.
By further illuminating the neurological processes of coordinated looking and reaching, associated with inhibitory beta waves, this study serves to better understand afflictions of attention and executive control.
The study is published in the journal Nature.