Science


NEUROGENESIS AND THE MAKING OF MEMORIES

The brain continues to produce new neurons throughout life, a process known as neurogenesis. Nearly two decades ago now, Dr. Shors and her collaborator Dr. Gould associated these new neurons in the hippocampus with processes of learning and memory. Perhaps more importantly, they found that many of these new neurons die within weeks but learning can keep the new neurons alive. These findings relate to the expression “Use it or lose it.” Not all types of learning keep new neurons alive. It turns out that the neurons only survive if learning itself occurs and the process is effortful. Others discovered that aerobic exercise increases neurogenesis in the hippocampus. Thus, both learning and exercise can increase the number of new neurons in the brain. The combination of these two activities is known as MAP Training, because it combines “mental and physical” training.

SEX DIFFERENCES IN THE BRAIN

In the distant past (1998!), Dr. Shors and her graduate student reported significant sex differences in stress and learning (Wood and Shors, 1998). Amazingly, exposure to a stressful event enhanced learning in a male rat but essentially prevented learning in the female. Her lab further found that these sex differences in learning are mediated by different brain circuits in males versus females. They are dependent on both activational and organizational effects of hormones such as estrogen and testosterone. But importantly, stressful experiences affect females differently depending on whether they are virgins or mothers, young or old, on antidepressants or not. At the time, these sex differences were considered surprising and unusual but now that all laboratories must study both males and females, we know that they are not – sex differences are all around us.

Most recently, Dr. Shors has become committed to understanding the consequences of sexual violence on the female brain (Shors and Millon, 2016). She developed a novel model to study it in the laboratory. This model is referred to as SCAR, which stands for Sexual Conspecific Aggression Response. Female rodents exposed to an adult sexually-experienced male were less likely to learn and to take care of offspring. As a consequence, they retained fewer new neurons in their brain (Shors et al., 2016). Again, these results were found in laboratory animals and would not necessarily be evident in humans — but they nonetheless underscore the profound effect of sexual violence on behavior and biology of the female brain.

STRESS, TRAUMA AND THE FEMALE BRAIN

Women are much more likely to experience stress-related mental illnesses across their lifetime, including depression, anxiety and post-traumatic stress disorders. They are also much more likely to experience sexual harassment and violence. Thankfully, hope is not lost for females. For example, the experience of motherhood can protect females from some of the detrimental consequences of stressful life experiences. While stress tends to suppress learning in virgin females, it does not do so in females that have just given birth. Perhaps more surprisingly, females that have given birth at some time in their lives learn well, even after a stressful life event, and long after the offspring have left their mother’s side. Once a mother, always a mother.

It’s obvious — men and women are different. We act different, we look different and so of course our brains are different. But we are not only different from males; we are always different from a previous version of ourselves. The female brain changes from childhood throughout puberty to adulthood, from pregnancy to motherhood, menopause and beyond. We are always changing – and we can choose to change our brain.

TRANSLATIONAL NEUROSCIENCE

Professor Shors is committed to helping women overcome the trauma of sexual aggression and violence. Based on her laboratory studies, she developed MAP Training. This intervention, known as MAP Training My Brain™ is a novel brain/body intervention designed to enhance mental and physical health by exercising the brain and the body in one session.

We have provided it to hundreds of people over the past 5 years – and have documented significant increases in both mental and physical health. For example, MAP Training reduces depression by as much as 40% in people with clinical depression. It reduced anxiety nearly in half in young mothers who were previously homeless. And MAP Training increased responses to a measure of self-worth as well as perceived quality of life.

Perhaps most importantly, engaging in MAP Training decreases ruminations about the past – in numerous groups of people, including those with depression, trauma history, PTSD, and even in medical students! These results are encouraging because many of us spend time ruminating about our past, especially negative events and feelings about ourselves and things we have done. This preoccupation with the past often keeps us from living in the present moment. We can all benefit from a bit of MAP Training.