Chemosensory
Mission: The goal of the Chemosensory Neuroscience Focus Group (CNFG)
is to provide training and foster research in the chemical senses in
order to understand their neurobiology and the roles they play in the
function of the entire organism. The last decade has seen a spectacular
growth in chemosensory research.
The chemical senses taste and smell
are crucial players in enabling an individual to detect, characterize
and interact with chemical cues in the environment. Taste is involved
in the evaluation of soluble components that are present in food
and drink and thus plays a key role in the determination of the palatability
of food and in nutrition, especially mineral and energy balance.
Olfaction, or the sense of smell, is critical for monitoring the
presence of volatile compounds and is important for evaluating the
safety of the environment, for interpersonal interactions, and for
ingestive decisions. Taste and smell offer opportunities to study
different modes of sensory transduction: how chemical information
is converted to neural information. Both of these neural systems
possess sensory cells that are in contact with the environment and
that are continuously replaced during life. Therefore, these systems
are powerful models for the study of stem cells, regeneration, plasticity,
and development in the nervous system. The regenerative properties
of these neurons render them particularly promising as potential
sources for neuronal transplantation to ameliorate degenerative diseases.
Within the central nervous system, the olfactory bulb and piriform
cortex are attractive as model systems for the study of cortical
organization and function and for investigation of the neural basis
of learning and memory.
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Confocal image of individual olfactory cilia which are part
of olfactory neurons where odor molecules come into contact with
the nerve cell membrane and where the initial sensory transduction
of odor detection takes place. The image shows enhanced calcium
fluorescence following the activation of cyclic nucleotide gated
channels by 8-bromo cGMP. These cilia have a diameter of approximately
300 nm.
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Research
Applications of contemporary technologies
to research questions in the chemical senses are providing new insights.
Examples of such approaches include molecular cloning, genomic arrays,
transgenic mice, patch-clamp recording, functional in vitro tissue
slice preparations, and characterization of neural networks and of
functional synaptic organization. The faculty members encompass a
wide ranging set of skills, including hands-on expertise in modern
molecular methods, tissue culture, immunocytochemistry, in situ hybridization,
quantitative anatomical and functional imaging, electron microscopy,
intracellular, patch-clamp and extracellular electrophysiology in
both in vivo and in vitro preparations, neuropharmacology, and human
and animal psychophysical methods.
Researchers at the University of Maryland were the
first to develop an in vitro slice preparation of the mammalian olfactory
bulb, which has allowed the study of synaptic interactions within this
highly organized neural structure to proceed at an unprecedented pace.
This technique has been adopted by several other laboratories around
the world and is now at the cutting edge of neurophysiological research
in this area. It has also been extended within the group to include
slices containing both receptor neurons and the olfactory bulb, as
well as similar preparations of the vomeronasal system and the application
of both patch recording and calcium imaging to these preparations.
Investigators in this group have developed
a novel new preparation for patch recording from receptor cells in
intact taste buds maintained within the epithelium of the tongue
or palate, allowing for the first time the application of a wide
range of taste stimuli to these cells. The pharmacology of synaptic
interactions in the olfactory bulb and the gustatory brainstem are
the subject of research in this area. Researchers in this group were
the first to identify glutamate as the primary neurotransmitter at
the olfactory bulb and in the nucleus of the solitary tract in the
medulla (the first central gustatory relay nucleus). Application
of transgenic mouse technology is being used to study mechanisms
of sensory transduction and mechanisms regulating chemosensory gene
expression. Characterization of molecules, the expression of which
changes during development and in response to other perturbations,
is being studied with genomic arrays. Thus, this group of scientists
brings state-of-the-art neurobiological expertise to the study of
all aspects of the chemical senses and the Program in Neuroscience
is internationally recognized as a leading research and training
center in this field.
Investigators and Extramural Support
At the University of Maryland Baltimore,
more than 30 faculty, postdoctoral fellows, and students work in
the Chemosensory Neuroscience Focus Group, primarily within the Department
of Anatomy & Neurobiology. Their research activities range from
the molecular biology of olfactory and taste receptors to the study
of humansensation. Currently, these investigators are funded through
individual NIH and National Science Foundation research grants, a
program project grant, and an NIH training grant, totaling over $3.5
million annually.
The
temporal sequence
of gene expression is critically important for normal
brain development.
In this experiment, we used modern molecular biology
approaches to
simultaneously compare the expression of 12,
000 genes (~1/3
of the mammalian genome) between adult and infant
brain in a search
for genes that maybe important for brain development.
Each point of
light on the array and each dot on the graph represents
the expression
of a single gene in adult and infant. |
Challenges for the Future
Change is
the only constant in research. The speed
with which technology is advancing makes it imperative
that the CNFG continue to have the ability
to take advantage of the most current methodologies.
These include advances in genomics, proteomics,
informatics, imaging, microscopy, and
gene modification and delivery.
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