
Adolescence is a critical period for brain development, characterized by complex changes in neuronal circuits that underpin cognitive and behavioral maturation. Shannon Gourley, PhD, studies the basic biology of how the brain develops during adolescence. While the early stages of brain development in infants and young children have been well-studied, the specific biological processes underlying adolescent brain maturation are less well understood. This gap in knowledge is particularly important given the vulnerability of the adolescent brain to external stressors, addictive substances, and genetic factors that may predispose individuals to neurodevelopmental disorders like autism spectrum disorder (ASD) or depression.
The research conducted in Dr. Gourley’s lab primarily employs mouse models to study brain development during adolescence. While humans experience adolescence between the ages of 12 and 24 years, adolescence in mice begins at around 28 days of age and culminates in young adulthood at around 56 days. This four-week window provides an ideal model to study the biological and behavioral changes that characterize adolescence in mammals.
In Dr. Gourley’s studies, mice are exposed to various stressors, such as social isolation, or genetically modified to carry high-risk genes associated with ASD. These models allow Dr. Gourley’s lab to investigate the effects of these factors on neuronal development in the frontal cortex, a brain region critical for executive functions such as planning, impulse control, and decision-making. High-resolution imaging techniques are used to observe and manipulate the development of individual neurons. Behavioral tasks are also employed to assess cognitive abilities, including the ability to adapt to rule changes and engage in goal-directed behavior.
One of the key findings of Dr. Gourley’s research is the impact of social isolation during adolescence on the development of neurons in the frontal cortex. Normally, during adolescence, neurons undergo a process of pruning, where unnecessary branches (synaptic connections) are eliminated, and important connections are strengthened. However, when mice are exposed to social isolation during this critical period, this pruning process is disrupted, leading to an overabundance of neuronal branches. This phenomenon results in impaired cognitive function, such as deficits in inhibitory control and long-term planning, and is associated with depression-like behavior in the affected mice.
Dr. Gourley also investigated potential interventions to reverse these deficits, for instance focusing on Rho-associated protein kinase (ROCK), a protein that regulates the shape and structure of neurons. ROCK has been shown to inhibit the pruning process during adolescence, and its inhibition in her mouse models allowed the neurons to undergo normal pruning, even in the context of social isolation. The inhibition of ROCK led to improvements in executive function and a reduction in depression-like behavior in the affected mice. Dr. Gourley has found evidence that interventions targeting the ROCK signaling pathway may be effective in reversing these deficits, offering new avenues for therapeutic interventions in neuropsychiatric conditions. As she continues to explore the molecular mechanisms driving adolescent brain development, she hopes to pave the way for novel treatments that could improve the lives of individuals affected by developmental disorders.