Researchers discover a brain signal that predicts child attention lapses

Inside a world-leading deep brain stimulation program at The Hospital for Sick Children (SickKids), researchers have discovered a brain signal that predicts when a child is about to lose attention - and that a brief, targeted intervention in response to that signal can restore their focus. 

Their study, published in Nature Neuroscience, represents the first time this approach for attention control has been studied in people. 

Few aspects of the human experience are as integral as attention. It shapes our perceptions, memories and interactions, but what happens when it is compromised?" 

Dr. George Ibrahim, lead author, neurosurgeon and Senior Scientist in the Neurosciences & Mental Health program

While fluctuations in attention are natural, disruptions in "attentional flexibility" that occur in youth with attention deficit/hyperactivity disorder (ADHD) can have negative behavioural, psychosocial and academic consequences. Medications used today are limited in their impact because, up to now, we didn't know exactly how attention lapses happen nor which neural networks in the brain are involved. 

Unique study offers new insights in the brain 

The study began first with an attentional set-shifting task - which measures how attention shifts between stimuli - in a group of 30 children with epilepsy, a condition that significantly raises one's risk for ADHD. 

The team performed intracranial recordings, in which electrodes record directly from the depth of the brain, enabling them to monitor neural activity in milliseconds. At the same time, they used machine learning models to predict fluctuations in attention - which is a world-first. Through the models, they pinpointed a specific pattern of brain activity that anticipated slow or fast attention shifts in all children over several days. 

"We were amazed to detect a signature in the brain that arose just before each child's attention shifting performance was delayed," says Dr. Nebras Warsi, first author and paediatric neurosurgeon-scientist studying in the Ibrahim Lab. "With precision electrical stimulation right at these moments in time, every child stayed engaged despite the difficult tasks and performed them faster and more accurately." 

During various 20- to 30-minute tasks, they monitored the children's performance through eye-tracking, reaction time and accuracy to spot lapses in attention. The brief electrical stimulation saved their attention only when delivered right at exact moments; when delivered at other times, the participant's performance declined. 

In short: timing was everything. 

Expanding the scope to other children 

Could the same results be expected in other children without epilepsy? To find out, the researchers used non-invasive magnetoencephalography imaging in 37 typically developing kids and 25 with ADHD. 

By targeting that same signal in their brains, researchers could once again predict attention delays. Next, they used noninvasive transcranial magnetic stimulation-electroencephalography (TMS-EEG) and found that one pulse, delivered to that target area, led to significantly improved reaction time and accuracy. This time with a simple EEG cap and TMS coil, with no need for intracranial brain electrodes. 

This suggests long-term potential for non-invasive tools that could support attention right when it's needed most. 

While these technologies are still in their early days, Ibrahim says this opens a promising new direction for understanding attention challenges and being able to advance Precision Child Health at SickKids, and around the world, by supporting each child in an individual way. 

"Many people are studying neurological and neuropsychiatric disorders in adults, but very few people are expanding into paediatrics," says Ibrahim, who is also the Abe Bresver Chair in Functional Neurosurgery. "We need to ethically advance possible therapies for children and youth and, to do that, we need to understand neural circuitry. 

"The potential to change the lives of so many children is profoundly important." 

The study is supported by the Canadian Institutes of Health Research (CIHR), Brain Canada through an Azrieli Future Leader in Canadian Brain Research Award, and the Abe Bresver Chair in Functional Neurosurgery at SickKids. Dr. Warsi is supported by the CIHR Vanier Scholarship, the James and Mari Rutka Surgeon-Scientist Award, and the Edward Christie Stevens Fellowship in Medicine.