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One patient can still spot faces post-surgery, suggesting perception network is resilient

6512816693_bb3b81b907_zIn what might be reassuring news to many of us, psychologist Kalanit Grill-Spector, PhD, and research associate Kevin Weiner, PhD, have found evidence of our brain’s resilience.

The pair, along with colleagues in France and Belgium, were looking at a particular part of the brain that feeds information to a network involved in face recognition. They’d been curious what would happen in a brain that lacked what is believed to be the starting point for perceiving faces. Would that gap cause the rest of the network to shut down? Or does the brain have workarounds in case of malfunction in one region?

Studying these questions is challenging because, let’s face it, people aren’t volunteering to have part of their brain removed to see what happens. Psychologists like Grill-Spector are forced to infer the brain’s wiring from cleverly designed experiments in healthy people.

What’s different in this case is that a colleague in Belgium knew of a patient who could help. This patient – who they refer to as S.P. – had epileptic seizures originating near the region of the brain they were interested in studying, and was going to undergo a surgery that would permanently remove that region. (The surgery was successful in eliminating S.P.’s seizures.)

The Stanford and Belgium team ran a number of face recognition imaging studies on S.P. up to four days prior to the surgery and over the course of three years after the surgery, starting 30 days post-operation.

“To our knowledge, this is the first case study that has multiple neuroimaging sessions before and after surgery in the same patient,” Weiner told me.

That before and after data is important because Weiner said fMRI measurements can vary between people or even on the same person over time. For that reason, having data from both before and after the surgery gave them a way to compare and see what had changed.

In the end, the surprising finding was that little changed in S.P.’s face recognition network, even without what was considered to be the input. Wondering why the network remained so resilient, Weiner and the rest of the team identified several bypass pathways that reach the rest of the face perception network. The identification of these pathways led them to hypothesize that the brain has a number of workaround strategies for continuing to function in the case of damage or surgery. “Those routes may not always be involved in face processing, but they are there and we think they can pick up the slack if they need to,” Weiner said. They published their work last week in The Journal of Neuroscience.

“It made us feel great that she was seizure free and it is remarkable that her face processing network was so resilient after surgery. It also makes us wonder if all networks are this resilient or if some networks are more fragile than others,” he added.

Previously: In a human brain, knowing a face and naming it are separate worries and Metamorphosis: At the push of a button, a familiar face becomes a strange one,
Image by Amy Rachel

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