Keeping our eyes focused on what we’re looking for, whether it’s an item at the grocery store or a ball on the ground at the baseball field, may seem seamless, but, in fact, it’s because of a complex neurological process involving complex timing and coordination. In a study recently published in the journal Naturea team of researchers sheds further light on the machinations that ensure we don’t take our eyes off where we are coming from.
The work centers on a form of gaze and coordinated reaching called “gaze anchoring” – the temporary stopping of eye movements in order to coordinate reaches.
“Our results show that we anchor our gaze to the target of the range motion, thereby gazing at that target for longer periods of time,” says Bijan Pesaran, a professor at NYU’s Center for Neural Science and one of the paper’s authors. . “That’s what makes our ranges so much more accurate. The big question was, 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 frequently studied but poorly understood process of gaze anchoring, specifically how different regions of the brain communicate with each other.
To examine this phenomenon, scientists studied brain activity in the arm and eye movement regions of the brain at the same time that non-human primates performed a sequence of eye and arm movements. The first move was a coordinated look and reach at a target. Then, as little as 10 milliseconds later, a second target was presented for the subjects to look at as quickly as possible. This second eye movement revealed the gaze anchoring effect. These movements are similar to those performed when changing radios while driving and attending a traffic light – if you quickly look away from the radio towards the traffic light, you may not select the correct channel .
Their results showed that, during gaze anchoring, neurons in the part of the brain – the region of parietal involvement – are used to reach work in order to inhibit the activity of neurons in the part of the brain – the parietal saccade region – used for eye movements. . This suppression of neural firing serves to inhibit eye movement, keeping our eyes focused on the target within our range, which then improves the accuracy of what we grasp. Importantly, the scientists note, the effects were linked to patterns of 15-25 Hz brain waves, called beta waves, which organize neural firing in different regions of the brain.
“Beta waves have previously been linked to attention and cognition, and this study reveals how beta activity can control inhibitory brain mechanisms to coordinate our natural behavior,” says Pesaran.
By shedding more light on the neurological processes of coordinated seeking and reaching, linking them to inhibitory beta waves, this study offers the potential to better understand disorders of attention and executive control that orchestrate natural behaviors such as coordinated research and reaching.
The research was supported by the National Institutes of Health (T32 EY007136), Australian Research Council (DE180100344), National Science Foundation (BCS-0955701), National Eye Institute (R01-EY024067), Army Research Office , the Simons Foundation, a McKnight Scholar Award, and a Sloan Fellowship.