Hormonal
factors influencing adult neurogenesis
We have shown that glucocorticoids
negatively regulate adult neurogenesis - removal
of glucocorticoids by adrenalectomy stimulates adult neurogenesis while
injections
of corticosterone suppress adult neurogenesis. In some instances,
however,
elevated glucocorticoids are associated with either no change in adult
neurogenesis or the opposite effect (increased adult neurogenesis),
suggesting
that other factors can interfere with the glucocorticoid response. We
are
currently investigating the influence of neuromodulators and growth
factors on glucocorticoid
responses.
Rewarding experience and protection from glucocorticoids
Our lab is interested in understanding how rewarding
experiences can have health benefits despite activating systems
associated with
stress. We have shown that a rewarding
social experience (sexual experience) enhances adult neurogenesis and
dendritic
spine density. These findings seem
paradoxical since sexual experience also results in a large increase in
circulating glucocorticoids, hormones that typically inhibit neuronal
growth. We are currently investigating
the effects of sexual experience on hippocampal function.
Physical
activity and structural
plasticity in the hippocampus
Our lab studies the
effects of physical activity on adult neurogenesis,
dendritic architecture and dendritic spines in the hippocampus.
Running increases adult neurogenesis in the dentate
gyrus and enhances dendritic spine density throughout the hippocampal
circuitry. Some of these effects are modulated by the social context in
which
an animal lives. Ongoing studies are investigating the effects of
running and
stress on the activation of new neurons as well as the contribution of
running-induced structural change to alterations in hippocampal
function.
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Aging,
structural plasticity and
hippocampal function
Our lab is
interested in understanding the changes that occur in the
hippocampus as a result of aging with an aim toward identifying
conditions that
minimize structural and functional decline.
We have demonstrated a decline in adult neurogenesis during midlife in
primates. Others have demonstrated
similar effect in rodents, tree shrews and dogs, suggesting this is a
general
phenomenon of mammals. We are currently investigating conditions that
are
capable of stimulating adult neurogenesis in older animals.
Maternal and paternal
care
Parenting is a complex experience that is both stressful and
enriching. Our lab studies the influence
of parenting in a variety of species that display different parenting
styles,
including rats, California
mice and marmosets. We have shown that
parenting is associated with neuronal growth in the prefrontal cortex,
findings
that are consistent with living in an enriched environment. We
have also shown that maternal as well as paternal care result in a
decrement in
adult neurogenesis in the hippocampus. These
changes may contribute to some of the
behavioral changes
associated with parenting.
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