fMRI scanner at a neuroscience lab (Photo credit: Wikipedia)
This Top 10 list isn’t meant to be exhaustive (given how many studies are published each year, it never could be), but it’s a sturdy sampling of incredible work being conducted around the world, moving us closer to solving some extremely vexing puzzles about brains and behavior. Putting it mildly, 2013 was an eventful year for brain science.
1. How the Brain Takes Out Its Trash While We Sleep
In 2013, layers were peeled back from two interrelated mysteries: the function of sleep, and how the brain removes its waste byproducts.
While it’s been known for some time that the brain doesn’t directly use the body’s lymphatic system (our body-wide filtering and waste removal system) to dump its toxic waste, the mechanism that it does use wasn’t identified until 2012. The research team that made this discovery was led by University of Rochester neurosurgeon, Maiken Nedergaard, who dubbed the brain’s waste-removal mechanism the “glymphatic system.”
The glymphatic system relies on cerebrospinal fluid (CSF) to flush out neurotoxins via pathways separate from the lymphatic system. Among the toxins that are flushed is beta amyloid, a protein that’s found in clumps in the brains of Alzheimer’s sufferers.
In 2013, Nedergaard’s research team followed up on this discovery by identifying “hidden caves” that open in the brain while we sleep, allowing cerebrospinal fluid to flush out neurotoxins through the spinal column.
The implications of this research can’t be overstated: failing to get enough sleep isn’t just a bad idea for all of the reasons we already know, but over time it could also lead to neurological disorders like Alzheimer’s. If the study’s findings are accurate, our brains need sleep to remove waste byproducts like amyloid beta that eventually become brain killers.
The study was published in the journal, Science.
2. To Your Brain, Me is We
A 2013 study from University of Virginia researchers supports a finding that’s been gaining science-fueled momentum in recent years: the human brain is wired to connect with others so strongly that it experiences what they experience as if it’s happening to us.
The researchers had participants undergo fMRI brain scans while threatening to give them electrical shocks, or to give shocks to a stranger or a friend. Results showed that regions of the brain responsible for threat response – the anterior insula, putamen and supramarginal gyrus – became active under threat of shock to the self; that much was expected.
When researchers threatened to shock a stranger, those same brain regions showed virtually no activity. But when they threatened to shock a friend, the brain regions showed activity nearly identical to that displayed when the participant was threatened.
“The correlation between self and friend was remarkably similar,” said James Coan, a psychology professor in U.Va.’s College of Arts Sciences who co-authored the study. “The finding shows the brain’s remarkable capacity to model self to others; that people close to us become a part of ourselves, and that is not just metaphor or poetry, it’s very real.”
The study was published in the journal, Social Cognitive and Affective Neuroscience.
3. Your Brain Sees Even When You Don’t
A 2013 study published in The Journal of Neuroscience suggests that the brain can “see” someone else’s actions even when the ability to visually see has been destroyed.
Cortical blindness refers to the loss of vision that occurs when the primary visual cortex no longer functions, generally as the result of injury. There’s no longer an ability to visually perceive the world in the sense with which we’re most familiar (even though the eyes still technically work), but that doesn’t necessarily mean the brain no longer sees.
In this study a patient with full cortical blindness could still react to another person’s gaze. While in an fMRI machine, the patient was exposed to gazes directed at him and gazes directed away from him. On the face of it, neither should matter. His visual cortex couldn’t perceive any sort of gaze. But the brain scan indicated that another part of his brain definitely could.
The patient’s amygdala, the brain area associated with figuring out whether external stimuli is a threat, showed a distinctly different activation pattern when the gaze was directed at the patient than when directed away from him.