Writing in the latest issue of the journal Current Biology, the team describes how they recorded the activity of individual visual-targeting neurons in patients with electrodes implanted in their brains for epilepsy treatment. Piggybacking on this unique clinical setup, the researchers had patients search for target images within other pictures -- similar to how someone looks for Waldo in the Where's Waldo? books. While they were recording neural activity, they also tracked the patients' eye movements, so they could tell exactly which part of the image the patients were looking at.
When the patient found the target objects, neurons were activated in two areas of the brain: the medial temporal lobe, a region known to be involved in memory and object recognition, and the medial frontal cortex, a region known to be involved in control and decision-making.
Discovery - Cells - Brain - Respond - Target
"This was the first discovery of cells in the human brain that respond just when you look at a visual target," explains the study's lead author, Shuo Wang (PhD '14), who was a graduate student in Caltech's Computation & Neural Systems program and subsequently a postdoctoral fellow at Caltech when the experiments were done. He is now an assistant professor at West Virginia University.
While a few studies had previously found such neurons in the temporal cortex of monkeys, the experiment had never been done in a human subject. The researchers also found that the neurons in the medial temporal lobe responded about 200 milliseconds later than those in the medial frontal cortex.
Difference - Hypothesis - Cortex - Target - Feeds
"This difference supports the hypothesis that the frontal cortex first detects that a target has been found, and then feeds that...
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