We study how the brain changes in response to experiences, acting in part via the internal environment of the body in the form of circulating hormones. Hormones of the gonads and adrenal glands regulate neuronal structure (synapse formation, remodeling of dendrites, and neurogenesis) in the adult brain via genomic and non-genomic receptors that work in concert with neurotransmitters, such as glutamate, as well as other mediators. Estrogens and androgens induce new synaptic connections in brain areas such as the hippocampus, a structure that is important in learning and memory. These same hormones also modulate damage produced in stroke, head trauma and seizure (glucocorticoids exacerbating and estrogens protecting). Age-related changes in brain function and cognition are also likely to involve decreasing influences of gonadal hormones and increasing effects of adrenal glucocorticoids and other mediators such as inflammatory cytokines.

Stress is studied in terms of its effects on brain centers involved in emotion, such as amygdala, and in learning and memory, such as the hippocampus and prefrontal cortex, which are sensitive to the effects of hormones. Our emphasis is on the mechanisms underlying "adaptive structural plasticity", i.e. remodeling of dendrites, turnover of synaptic connections and neurogenesis. These studies investigate actions of estrogens and androgens on these same structures in relation to memory and emotions. Research in the lab concentrates not only on the mechanisms for structural plasticity but also on the mechanism whereby gonadal steroids protect neurons from damage and promote repair. Studies are underway on microglial cells and also putative neural stem cells.

In studying both stress and sex hormones as regulators of structural plasticity in the adult brain, it is necessary to consider sex differences and how they develop, along with the influences of early life experiences, in affecting learning and memory, as well as predisposition towards disease. Although the laboratory does not do translational studies on human clinical populations, we collaborate with investigators who do such studies