Where fish brains and human brains converge

Does the secret to solving conditions like attention deficit disorder lie in the brain of a fish? It’s not out of the realm of possibility, says a Ben-Gurion University professor who was part of a team that undertook an unusual study on how fish pay attention.

Human beings and fish don’t have much in common, but one thing they do share is an ability to direct visual attention at a target in order to achieve a goal, and to ignore stimuli that will divert them from that goal.

A study by researchers at Ben-Gurion University using archer fish shows that humans and fish, as well as other animals, direct their visual attention in similar ways. The researchers — Prof. Avishai Henik, Dr. Shai Gabay, and PhD student Tali Leibovich from the Psychology Department, and Prof. Ronen Segev and Dr. Avi Ben Simon from the Life Sciences Department — published their findings in the April issue of the scholarly journal Nature Communications.

Attention, a critical component of the human cognitive process, is the ability to concentrate on a specific aspect of the environment or specific information processing task in the brain, said the scientists. Since humans use vision extensively, visual attention has largely been the focus of the scientific community. By moving our attention around we can concentrate our brainpower on a specific task important to us at the moment. For example, students focus by looking at a whiteboard in a classroom.

Sometimes, attention shifts without intention. For example, a door slamming during class will immediately draw people’s attention and make them look at the door reflexively. But after the door slams several times, people tend to pay less attention to the phenomenon, especially if there has been a lag between the incidents in the same location.

Research indicates that this slowdown may be our way of preventing searching the same location more than once, the scientists said. This ability is important for both humans and animals. For example, there is no point in looking for your keys, if you are human, or prey, if you are an animal or a human, in the same place twice during a very short period. This complex process of moving visual attention around can improve the ability of animals to forage for food or other important items in their environment.

Previous studies have suggested that this slowdown in returning to an already searched location — termed inhibition of return (IOR) — is triggered by a midbrain structure named the superior colliculus. However, further research suggested that actually more advanced cortical structures were essential for inhibition of return.

Which was a bit puzzling for the scientists; fish have a superior colliculus in their brain, but, unlike humans, they lack fully developed cortical structures. In their study, the Ben-Gurion scientists observed IOR in the archer fish. “The behavior for the fish and for humans is similar, and the fact that both humans and fish have a superior colliculus would indicate at least a partial connection in humans to between that part of the brain and visual attention, if not a full connection, as is the case with animals who do not have a cortical structure,” said Professor Henik.

The BGU team selected the archer fish to serve as the model because of its remarkable ability to shoot down with its saliva insects found on foliage above the water level and its ability to learn to distinguish between artificial targets presented on a computer monitor in an experimental setting. They found that the fish presents similar attention effects to those of human participants, demonstrating the presence of inhibition of return even in a species lacking a fully developed cortex.

The results were interesting enough, said Professor Henik, that the team decided to continue studying the archer fish, in order to see what else can be learned about the colliculus, because the research indicates that it may hold some still undiscovered secrets — perhaps having to do with attention deficit disorders.

ADHD and similar disorders are generally considered to be under the control of the more advanced cortical area of the brain, said Henik. “The attention system controlling visual attention is located in a lower-functioning level of the brain than one than that which controls behaviors associated with ADHD, called the executive function system, located in the prefrontal cortex.

“So there is no direct connection between our study and ADHD,” Henik continued. “But we did see hints that there is more to the colliculus than previously thought, including perhaps some functions in humans that we associated with the cortex.” The studies will continue, said Henik – and just maybe, the brain of the archer fish could end up helping develop ways to help human kids.