Mary Blue PhD

Associate Professor of Neurology
Telephone Number: 443-923-2693
Fax Number: 443-923-2695

Johns Hopkins University
Kennedy Krieger Institute
707 N. Broadway St.
Baltimore, MD 21205
Room: BRB 400R
Areas of Research
Developmental Neuroscience
Systems, Cognitive + Computational Neuroscience
Neural Circuits, Ensembles + Connectomes
Cellular + Molecular Neuroscience
Neurobiology of Disease

Graduate Program Affiliations

Neuroscience Training Program

Neurotransmitter Mechanisms in Development and Activity-Dependent Plasticity

The research in my lab examines the roles neurotransmitters play as trophic agents in cortical development and plasticity. Our research has demonstrated that monoaminergic and glutamatergic neurotransmitter systems are both altered by and influence injury in neonatal and adult hypoxia-ischemia animal models and in specific developmental disorders such as Down syndrome, autism and Rett syndrome (both in postmortem tissue and in animal models). Activity-dependent plasticity plays an important role in the "sculpting" of synaptic connections in the postnatal human cerebral cortex and in the "reassignment" of cortex during recovery after early brain injuries. Our plasticity studies focus on mechanisms by which cerebral cortex is influenced by peripheral stimuli and by which function is reassigned from one area of brain to another after neonatal injury. To study these mechanisms we use the rodent whisker-to-barrel system as a model of cortical plasticity. Rats and mice use their whiskers to navigate in their world and a precise "map" of the rodent face and whiskers is relayed through the brain to the cerebral cortex. Specialized anatomical configurations called "barrels" structurally and functionally linked to individual whiskers. Much like the reorganization of the human cortex after amputation, peripheral injury resulting from ablation of a single whisker follicle produces atrophy of the cortical barrel connected to it, and enhanced growth of surrounding barrels. Our results suggest that glutamate receptors appear to mediate activity-dependent enlargement of some barrels and retraction of others in response to whisker clipping. Other studies have shown that neurotransmitter-specific afferents to the cortex (including acetylcholine-containing axons from the nucleus basalis) influence the degree of cortical plasticity. We have also used the model to investigate the effects of lead on the developing cortex. Lead poisoning in young children causes permanent loss of intelligence and remains common among poor urban children. Approximately 5% of the children tested in Baltimore from 1996 to 1998 suffered lead poisoning (blood lead greater than 20 g/dl). Studies underway in collaboration with Drs. Mary Ann Wilson, Michael V. Johnston and Gary W. Goldstein at the Kennedy Krieger Institute indicate that that low levels of lead exposure, comparable to those seen in many impoverished urban children, cause structural alterations in the developing barrel fields. This may involve the impact of lead on activity-dependent plasticity by increasing "synaptic noise" at glutamate receptors.

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