New research from a team led by a psychologist at the University of Kent suggests that humans, like other species, can perceive certain scents as threatening.
Dr Arnaud Wisman, of the University’s School of Psychology, found that putrescine, the chemical produced by decaying tissue of dead bodies, can produce a fight-or-flight response in humans.
In four different experiments, people were exposed consciously and non-consciously to putrescine.
The results, published in the journal Frontiers in Psychology, show that putrescine can serve as a (non-conscious) signal that initiates threat management responses. The researchers found that even brief exposure to putrescine increases vigilance, followed by the readiness to either escape (flight), or engage in aggressive readiness (fight) when escape is not possible.
Sleep is usually considered an all-or-nothing state: The brain is either entirely awake or entirely asleep. However, MIT neuroscientists have discovered a brain circuit that can trigger small regions of the brain to fall asleep or become less alert, while the rest of the brain remains awake.
This circuit originates in a brain structure known as the thalamic reticular nucleus (TRN), which relays signals to the thalamus and then the brain’s cortex, inducing pockets of the slow, oscillating brain waves characteristic of deep sleep. Slow oscillations also occur during coma and general anesthesia, and are associated with decreased arousal. With enough TRN activity, these waves can take over the entire brain.