How body and mind react to stress
Have you come across the situation where you scratch your head and bite your lips repeatedly during a tough interview? Did you wonder where those unconscious reactions come from? Neuroscientist Professor Wing Ho Yung (Croucher Fellowship 1990), at the Chinese University of Hong Kong, might now be heading towards an answer.
Yung and fellow neuroscientist Professor Ya Ke, both working at the University’s School of Biomedical Sciences and Gerald Choa Neuroscience Centre in the Faculty of Medicine, led a research team that has discovered a mammalian brain circuitry underlying our ability to generate adaptive responses when facing stress with strong negative emotions.
The scientists identified a previously unknown circuitry in rats’ limbic system, an important emotion-processing system in the brain, that mediates stress-induced repetitive grooming behaviour. This circuitry is specific to emotional stress in rat models, such as exposure to a threatening environment and long-term body constraint, but not to physical stress such as wetting the body.
Utilising a combination of cutting-edge optogenetic and chemogenetic techniques, the research team discovered that when the circuit was activated, animals displayed instant repetitive behaviour. On the contrary, when the circuit was inhibited, repetitive behaviour that otherwise could be evoked by emotional stress was largely prevented.
Intriguingly, the team also found that the animals “feel” good when this neural circuit is activated. This was revealed in experiments in which the rats were put into two connected chambers with the circuit activated only when the animal entered one but not the other chamber. The researchers found that the rats remembered the treatment and would later spend much more time in the chamber associated with activation of the circuit.
This suggests that activation of this specific circuit could help soothe the animals and so reduce their stress. It may also imply that trying to suppress such repetitive behaviour may not be necessary as it is considered beneficial.
Yung noted that as people’s normal response to stress could go awry in some neuropsychiatric disorders where excessive repetitive behaviour is common, for example, obsessive compulsive disorders or developmental disorders such as autism, the findings “not only uncover a limbic circuit that plays a significant role in emotional stress, but also provide a basis for probing the origin of malfunctions that could lead to abnormal repetitive behaviour exhibited in different brain disorders”.
The results of the study were recently published in Nature Communications.
Professor Yung Wing Ho graduated from The Chinese University of Hong Kong in biology and biochemistry with first class honours. He was a recipient of a Commonwealth Scholarship and Croucher Foundation Fellowship that supported his DPhil study and post-doctoral training at the University of Oxford, under the supervision of Professor Julian Jack. He is currently Professor in the School of Biomedical Sciences and Director of the Gerald Choa Neuroscience Centre, Chinese University of Hong Kong. He received his Croucher Fellowship in 1990.
To view Professor Yung’s Croucher profile, please click here.