Wayne Brake and the nature-nurture debate
Neurobiologist on the development of anxiety
Psychology professor Wayne Brake has been researching the complex question of whether genes or environment determine our actions: “Most of us agree now that it’s both."
Brake gave the first lecture in this year’s colloquium series organized by the Centre for Studies in Behavioural Neuro-biology.
He says it’s a mistake to look for an answer in just one place.
“Studies show that college students who report their relationships at home to be cold or distant are much more likely later on to experience a higher risk for depression and drug abuse.
“What we’re trying to get at is, does a nurturing, caring environment or a cold abusive relationship change the way the brain develops? Can we change our genetic backdrop?”
To investigate the question, Brake and his colleagues developed a mouse model of neglect.
Mice were an obvious choice because their genes are well understood and easy to manipulate. Brake chose an inbred strain wherein each mouse is genetically identical.
These inbred mice have become an important new tool in Brake’s research. “It’s about time, as behavioural neurobiologists, that we tapped into this resource."
In order to model neglect, Brake separated mother mice from their young pups for brief periods of time.
The day after these separations, the mother mice did not groom their pups as much as mothers who had never been separated. When their male offspring became adults, they showed higher levels of anxious behaviour. Brake was curious about what would be found in the female offspring.
“We know that levels of anxiety are affected by levels of circulating estrogen and progesterone.” Estrogen and progesterone are female sex hormones found in both mice and humans. Levels of the two hormones vary across the menstrual cycle in women, and across a similar four-day cycle in mice.
Female mouse offspring who had been separated from their mothers while they were young showed less anxious behaviour, but only during certain periods of their four-day cycle.
Brake then did a gene-chip analysis. Gene-chip analysis lets researchers screen samples for gene expression to quickly determine which genes are turned “on” or “off.”
In his study, the genes for growth factors, proteins linked to the growth and maturation of neurons, were particularly affected.
According to Brake, his model shows that interference with normal maternal behaviour across just seven days in the mouse “can dramatically change the expression of genes in the prefrontal cortex.”
Stress and anxiety are caused by “what you inherit combined with the environment as you grow up.”
Brake did his doctorate at McGill and his postdoctoral research at Rockefeller University. He began teaching at the University of California in 2001 and was hired at Concordia in 2005.
He said he loves his new position.
“I have a lot of colleagues whose work overlaps with mine, and I like the students because they tend to be naturally interested.”
His favourite part of the job, aside from the research, is having undergraduate students come into the lab. “That level of mentoring is extremely rewarding.”