Brain's mysterious switchboard operator revealed

Washington, August 18 (ANI): A mysterious region deep in the human brain could be where we sort through the onslaught of stimuli from the outside world and focus on the information most important to our behaviour and survival, a new study has found.

According to the researchers from Princeton University, an area of our brain called the pulvinar regulates communication between clusters of brain cells as our brain focuses on the people and objects that need our attention.

Like a switchboard operator, the pulvinar makes sure that separate areas of the visual cortex - which processes visual information - are communicating about the same external information, lead author of the study Yuri Saalmann, said.

Without guidance from the pulvinar, an important observation such as an oncoming bus as one is crossing the street could get lost in a jumble of other stimuli.

The researchers have found that the pulvinar, a mysterious region deep in the human brain, acts like a switchboard operator to make sure that separate areas of the brain are communicating about the same external information most important to our behaviour at a given moment.

The pulvinar uses electrical impulses to synchronize and allow more effective communication between brain cells in the visual cortex, which processes visual information.

The researchers produced neural connection maps that show the pulvinar's connection to these brain regions. In this scan, the pulvinar communicates with the occipital lobe and the temporal lobe individually, and with both.

Saalmann said these findings on how the brain transmits information could lead to new ways of understanding and treating attention-related disorders, such as attention deficit hyperactivity disorder (ADHD) and schizophrenia.

The researchers developed a new technique to trace direct communication between clusters of neurons in the visual cortex and the pulvinar.

They produced neural connection maps using magnetic resonance imaging (MRI), then placed electrodes along those identified communication paths to monitor brain signals of macaques.

The researchers trained the monkeys to play a video game during which they used visual cues to find a specific shape surrounded by distracting information. As the macaques focused, Saalmann and his colleagues could see that the pulvinar controlled which parts of the visual cortex sent and received signals.

"A fundamental problem for the brain is that there is too much information in our natural environment for it to be processed in detail at the same time. The brain instead selectively focuses on, or attends to, the people and objects most relevant to our behaviour at the time and filters out the rest. For instance, as we cross a busy city street, our brain blocks out the bustle of the crowd behind us to concentrate more on an oncoming bus," Saalmann said.

"The transmission of behaviourally relevant information between various parts of the brain is tightly synchronized. As one brain area sends a signal about our environment, such as that a bus is approaching, another brain area is ready to receive it and respond, such as by having us cross the street faster.

"A persistent question in neuroscience, though, is how exactly do different brain areas synchronize so that important information isn't lost in the other stimuli flooding our brains.

"Our study suggests that a mysterious area in the centre of the brain called the pulvinar acts as a switchboard operator between areas on the brain's surface known as the visual cortex, which processes visual information.

"When we pay attention to important visual information, the pulvinar makes sure that information passing between clusters of neurons is consistent and relevant to our behaviour.

"These results could advance the understanding of the neural mechanisms of selective attention and how the brain transmits information. This is a necessary step in developing effective treatment strategies for medical disorders characterized by a failure of attention mechanisms. These conditions include ADHD, schizophrenia and spatial neglect, which is an inability to detect stimuli often observed following stroke," he added.

The study has been published in the journal Science. (ANI)