By Anjanette Harris, University of Edinburgh, @anjiefitch
I have been to many music festivals in my time, but last month I went to my first Neuroscience Festival. Every two years, the British Neuroscience Association holds the Festival of Neuroscience, which boasts a jam-packed program of research talks from experts across many disciplines within neuroscience, as well as workshops and discussion forums. It is quite simply the national celebration of neuroscience.
Last month, nestled amongst the canals of Birmingham, the International Conference Center provided the perfect backdrop for over 1500 scientists from around the world to get together, share their latest data, and enthuse one another. This year, The Physiological Society hosted a strand running through the festival called The Neurobiology of Stress as part of their annual theme Making Sense of Stress. One of the symposia, organised by Professor Megan Holmes, brought together researchers from around the world, including myself, to present our work on imaging the emotional brain.
What puts us at risk of depression?
Dr Stella Chan, a lecturer in clinical psychology from the University of Edinburgh, kicked off with the staggering statistic that half of all cases of depression first occur in adolescence. Stella reminded us that adolescence is a tricky time in which teenagers struggle with intense emotions on the road to self-discovery. But why do some youngsters develop depression while others don’t?
To answer this question, Stella studies how young people perceive themselves and the world around them. One startling finding is that those at risk of depression find it harder to see joy in other people’s faces. Because Stella uses teenagers at risk of, but not yet suffering from, depression she is able to see if there are changes in perception that may flag up that a youngster is likely to develop depression. If Stella can untangle whether a negative self-opinion is the cause or consequence of depression, she may be able to develop mind-training techniques to prevent depression in those at risk.
Untangling cause and effect using mice
Dr Marloes Henckens, a post-doctoral researcher from the Donders Institute at Radboud University, presented her work on the effects of stress on brain function. She uses both human and mouse subjects to help her distinguish between cause and effect. Marloes began by setting her work in context; she highlighted that the brain is a collection of networks and that brain disorders are probably caused by disorders of the connections between different networks.
With that in mind, Marloes showed that stressing humans or giving them stress hormones caused the connections that make up the fear network to become stronger. While this is useful for priming a person to tackle danger, it may lead to an anxiety disorder, such as post traumatic stress disorder (PTSD) in which suffers are haunted by intense unpleasant memories. Marloes takes pictures of the brains of mice with PTSD-like symptoms and has shown that reduced activity at the front of the brain (important for reducing unpleasant memories) is a consequence and not the cause of PTSD. It remains to be seen how connections between different networks are affected in mice with PTSD.
Hormonal influences on brain activity in rats
The following speaker, Professor Craig Ferris of Northeastern University, is the pioneer of imaging rats’ brains while they are awake. Craig began with a whistle-stop tour of the groundbreaking technology that he and his team have developed. His special scanning technology allows researchers to monitor brain activity while the rats are responding to things. For example, Craig showed changes in brain activity in mother rats as their pups start to suckle. It comes as no surprise that the brain areas involved in reward and motivation are active with breast-feeding. In fact, in these rats, breast-feeding is more rewarding than cocaine!
Craig then presented images of brain activity involved in aggression. To observe this, he first took pictures of the brain of a male rat that was happily lying in the scanner with its girlfriend, and then introduced an unfamiliar male rat and observed the changes in the first rat’s brain. The abrupt change in brain activity that was seen in the male rat’s brain might be described as blind rage, as it is similar to that observed with the onset of a seizure. Craig’s ambition knows no bounds: he finished his talk with musing on whether he could fit a killer whale into his brain scanner!
The impact of stress on emotional memory in rats
The final speaker was me, Dr Anjanette Harris. I’m a post-doctoral researcher from the laboratory of Megan Holmes at the University of Edinburgh. I want to understand how stress affects brain function. This is particularly tricky to study in humans, especially if we want to look at the effects of early life stress on the brain, so we use rats (read more on the importance of using rodents in psychiatric research in my previous blog post). The work that I presented uses the technology of Craig Ferris coupled with memory exercises for rats that we specialize in designing. We have shown that rats that experience stress in early life form stronger memories of unpleasant experiences. These rats also have stronger activity in brain areas involved in fear when recalling unpleasant experiences in adulthood. This mirrors what is found in humans and means that we may be able to test potential therapies for human memory disorders on rats, ensuring that the treatments target appropriate areas in the brain.