Spatial orientation - knowing which way is up and which way is down - is such a basic, subconscious skill that most of us don't give much thought to it until our sense of space is disrupted and we feel like a cheap café chair that's a few shims short of being steady on its legs. If you've ever experienced a loss of spatial orientation, and the unpleasant sense of dizziness that accompanies it, read on.
Our basic sense of space is associated with a region of the brain located behind your ear, called the parietal lobe. But, until recently, scientists were unsure exactly which part, or parts, of the brain contribute to our sense of up and down. Now, a trio of researchers from Johns Hopkins University School of Medicine have located the precise part of the brain that plays an important role in our perception of standing upright. From a recent university press release:
"Our brain has this amazing way of knowing where we are in space, whether we are upright or tilted at an angle, even if it is completely dark and we can't see anything around us," says Amir Kheradmand, a neurology instructor at the Johns Hopkins University School of Medicine who conducted the research... His team focused their attention on the right parietal cortex because studies in stroke victims with balance problems suggested that damage to that part of the brain was centrally involved in upright perception.
As the press release explains, eight healthy people were asked to describe the spatial orientation of lines that were displayed on an illuminated screen before, and after a specific region in their right parietal lobe was stimulated. The stimulation, called trans-cranial magnetic stimulation (TMS), temporarily impairs the function of targeted brain area. By temporarily disrupting different locations in the brain, the researchers could identify the exact part of the brain that's associated with our sense of balance.
The researchers found that all of the subjects experienced the same skew in their sense of upright after receiving electromagnetic stimulation to a brain region of the brain, called the supramarginal gyrus.
Now that this region of the brain is identified, researchers know where to look, and where to treat the brain, if people are suffering spatial disorders. The research team hopes that someday, a TMS-based treatment could help people who suffer from chronic dizziness and spatial disorientation.
Holly MacCormick is a writing intern in the medical school’s Office of Communication & Public Affairs. She is a graduate student in ecology and evolutionary biology at University of California-Santa Cruz.