Assessing whether a fluffy bunny or a giant spider poses a threat to our safety happens automatically. New research suggests the same brain areas may be involved in both detecting threats posed by animals and evaluating other humans' intentions. The study, published in the May 11 issue of the Journal of Neuroscience, offers insight into a basic feature of human cognition: how we understand and evaluate other creatures.
"The idea that animals may be processed in a similar way [to humans] and may piggyback on regions of the brain that have been implicated in social cognition suggests that those regions ... are multipurpose," said study author Andrew Connolly of Dartmouth College.
Previously Connolly's research group found that hierarchical classes of animals (say, bugs vs. mammals) are represented in an area of the brain called the lateral occipital complex, a region involved in object perception and recognition. What was not known, however, was which brain regions process information about an animal's "dangerousness."
To investigate this, the researchers scanned volunteers' brains while they viewed pictures of bugs, reptiles, and mammals. Half of the animals depicted were classified as "low threat," such as butterflies and rabbits, and half were "high threat," such as snakes and cougars. Using functional magnetic resonance imaging (fMRI), the researchers determined which areas of the brain were active when participants viewed bugs, reptiles, and mammals, and when they viewed low- and high-threat animals. Researchers used these activity patterns to map how two kinds of information -- taxonomic class and threat -- are encoded in the brain.
As before, they found taxonomic class was represented in the lateral occipital complex. Surprisingly, a different area of the brain represented threat. This area, called the superior temporal sulcus, is a fold in brain tissue running just above the ear, and previous research has implicated the region in understanding facial expressions and deciphering others' intentions. The researchers speculate that evaluating other humans and evaluating threats posed by animals may be related functions.
Nikolaus Kriegeskorte, a neuroscientist at the University of Cambridge who studies visual object recognition and was not involved in the study, said this is interesting basic science. "Knowing what parts of the brain are involved in social cognition and how information processing works is relevant to our understanding of human brains, minds, and cultures."
The researchers are planning future studies to examine how activity in these brain networks changes over time. The present study used fMRI, which measures changes in blood flow as a proxy of neural activity, a measure that is slow and inadequate for understanding temporal relationships. To address this, the researchers plan to incorporate electrical recordings of brain activity in their studies.
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