Moose-collision memory loss reveals complex brain functions

The story of a Newfoundland man who was struck by a moose but doesn't remember it is not just a curious tale of luck. It also highlights the complex underpinnings of human memory, a neuroscience expert says.

Stephen Bromley, from Conche, N.L., struck a moose with his car on Monday, but said he had no recollection of it, even days after the collision.

It's not the first time that something was amiss about human memory after a moose encounter. 

Another Newfoundlander drove about 40 kilometres with her car's roof peeled back "like a sardine can" after crashing into a moose in 2012. Three years later, she said she still can't recall the incident.  

The blackout doesn't surprise Scott Watter, a McMaster University professor who specializes in neuroscience, psychology and behaviour.

"They are lucky in that sense, but it doesn't seem like a thing that breaks the rules of everything we know about how brains work," he told CBC News.

People who sustain head trauma often have poor memory of the event, especially when tested on specific details, Watter said.

Also, the more severe the injury gets, the further back the memory loss extends, Watter said.

Motor skills and memory

The system at the heart of our memory is a seahorse-shaped section of the brain called the hippocampus, Watter explained. It's responsible for linking different parts of human experience to form a coherent memory.

In the most severe — but rare — cases of hippocampus damage, the person can no longer create or retain new memory, as seen in Christopher Nolan's 2000 box office hit Memento.

The cases of the two Newfoundlanders appear to be much milder and hopefully more transient, Watter said.

"You probably experienced it at the time, and they may have thought, 'Oh my goodness! I'm gonna hit this creature!' But there's not enough time for that to be encoded in your long-term memory system before you get the physical shakeup."

What did catch Watter's attention, he said, is that both people managed to drive for some distance before they stopped.

It underscores that our brain is not a unitary organ, but is made up of a complex set of subsystems that are responsible for various functions, he said.

"It's certainly possible to have some of those things more functional than others for a small amount of time," he said.

According to Michelle Higgins, the woman behind the wheel in 2012, her doctor said her brain became overwhelmed in the collision and was unable to process what happened, so it shut down and took her to her destination on autopilot.

Moose tales met with incredulity

The moose stories garnered plenty of media coverage —  from local outlets to British tabloids — as well as incredulity from readers.

Higgins said when she is recognized by people who have read her story, she often gets asked, "How can you not remember?"

"People out there don't understand it and, oddly, I understand why they don't understand it, because I don't understand it," she told CBC News in an interview shortly after the incident.

The skepticism is just one example of the disconnection between our subjective experience and how the brain actually performs its functions, Watter said.

The moose-induced memory impairment doesn't line up with our everyday experience, making it difficult to believe, Watter said.

"Our subjective experience is sometimes so different to the way we find our brain actually works when we carefully study it," he said.

"I don't think it makes us any less human one way or the other. Our brain is the most complicated thing we know about."

Serious vehicle-animal collisions

The two Newfoundlanders lived to tell the tale, but collisions with animals can be deadly on Canada's roads.

In Newfoundland and Labrador alone, more than 350 animal-vehicle collisions were reported each year between 1999 and 2003. Over that period the collisions killed seven people, according to data from Transport Canada. 

Conservative MP Steven Fletcher remains paralyzed from the neck down because of a highway accident involving a moose in 1996.