1 . Directions: Fill in each blank with a proper word chosen from the box. Each word can be used only once. Note that there is one word more than you need
A. potentially B. results C. rewards D. sensitive E. survival
F. transmit G. distinguish H. responding I. developed J. conscious K. rapidly |
Sense of smell is our most rapid warning system
“The human avoidance response to unpleasant smells associated with danger has long been seen as a 1 perceivable process, but our study shows for the first time that it’s unconscious and extremely rapid,” says the study’s first author Behzad Iravani, researcher at the Department of Clinical Neuroscience, Karolinska Institutet.
The organ relating to the sense of smell takes up about five per cent of the human brain and enables us to 2 between many million different smells. A large proportion of these smells are associated with a threat to our health and 3 , such as that of chemicals and rotten food. Smell signals reach the brain within 100 to 150 milliseconds after being breathed in through the nose.
The survival of all living organisms depends on their ability to avoid danger and seek 4 . In humans, the smell sense seems particularly important for detecting and reacting to 5 harmful substance.
It has long been a mystery just which sensory systems are involved in the change of an unpleasant smell into avoidance behavior in humans. Researchers at Karolinska Institutet have now 6 a method that for the first time has made it possible to measure signals from the human smell organ, which processes smells and in turn can 7 signals to parts of the brain that control movement and avoidance behavior.
Their 8 are based on three experiments in which participants were asked to rate their experience of six different smells, some positive, some negative, while the electrophysiological activity of the smell organ when 9 to each of the smells was measured.
“It was clear that the organ reacts specifically and 10 to negative smells and sends a direct signal to the outer layer of the organ within about 300 ms,” says the study’s last author Johan Lundström. ” The signal causes the person to unconsciously lean back and away from the source of the smell.”
