Emory Brain Health researchers have developed a computer program that passively assesses visual memory. An infrared eye tracker monitors eye movements, while the person being tested views a series of photos.
This approach, relatively unstrenuous for those whose memory is being assessed, is an alternative for the diagnosis of mild cognitive impairment or Alzheimer’s disease. It detects degeneration of the regions of the brain that govern visual memory (entorhinal cortex/hippocampus), which are some of the earliest to deteriorate.
The approach was published in Learning and Memory last year, but bioinformatics chair Gari Clifford discussed the project at a recent talk, and we felt it deserved more attention. First author Rafi Haque is a MD/PhD student in the Neuroscience program, with neurology chair/Goizueta ADRC director Allan Levey as senior author.
Eye tracking of people with MCI and Alzheimer’s shows they spend less time checking the new or missing element in the critical region of the photo, compared with healthy controls. Adapted from Haque et al 2019.
The entire test takes around 4 minutes on a standard 24 inch monitor (a follow-up publication on an iPad version is in the pipeline). Photos are presented twice a few minutes apart, and the second time, part of the photo is missing or new – see diagram above. Read more
When processing what the eyes see, the brains of primates don’t use square grids, but instead use triangles, research from Yerkes neuroscientist Beth Buffalo’s lab suggests.
Elizabeth Buffalo, PhD
She and graduate student Nathan Killian recently published (in Nature) their description of grid cells, neurons in the entorhinal cortex that fire when the eyes focus on particular locations.
Their findings broaden our understanding of how visual information makes its way into memory. It also helps us grasp why deterioration of the entorhinal cortex, a region of the brain often affected early by Alzheimer’s disease, produces disorientation.
The Web site RedOrbit has an extended interview with Buffalo. An excerpt:
The amazing thing about grid cells is that the multiple place fields are in precise geometric relation to each other and form a tessellated array of equilateral triangles, a â€˜gridâ€™ that tiles the entire environment. A spatial autocorrelation of the grid field map produces a hexagonal structure, with 60Âº rotational symmetry. In 2008, grid cells were identified Gafas Ray Ban outlet in mice, in bats in 2011, and now our work has shown that grid cells are also present in the primate brain.
Please read the whole thing!
Grid cells fire at different rates depending on where the eyes are focused. Mapping that activity across the visual field produces triangular patterns.