Defining Central Circuits of Pain
| Status: | Archived |
|---|---|
| Conditions: | Gastroesophageal Reflux Disease , Gastrointestinal |
| Therapuetic Areas: | Gastroenterology |
| Healthy: | No |
| Age Range: | Any |
| Updated: | 7/1/2011 |
Defining Central Circuits of Visceral Pain
The purpose of the study is to use functional Magnetic Resonance Imaging (MRI) to help us
understand what parts of the subject's brain are involved when he experiences visceral pain,
or pain in the gut. To stimulate the brain, he will be infused with a liquid meal (Ensure)
into his stomach until he is maximally full. Magnetic resonance imaging (MRI) is a
technique for making images (pictures) of the brain; it uses magnetic fields and radio waves
and is not harmful. This study uses a new investigational technique called functional MRI
(fMRI), which is a very fast MRI technique that will allow the investigators to evaluate
changes in how blood flows to parts of his brain.
Dyspepsia, a condition characterized by upper abdominal discomfort, is one of the most
common types of pains in clinical practice and is one of the most common reasons for visits
to primary care physicians and gastroenterologists. But relative to somatic pain, little
fundamental information is known about visceral pain syndromes such as dyspepsia and
irritable bowel syndrome. Recent exciting advances in neuroimaging such as functional
magnetic resonance imaging (fMRI) have allowed investigators to interrogate neural signal
changes in humans in a wide variety of pain conditions. But to date neuroimaging has not
provided details of activation in specific neural circuits that are important in visceral
pain. In these experiments we will focus on specific regions of interest (ROI's) that have
shown to be relevant in animal models of pain circuitry including the dorsal column nuclei,
the thalamus, the hypothalamus, the amygdala and the periaqueductal gray.
The specific aims of our proposed project are:
1. To measure fMRI signal in primary visceral afferent pain pathways (dorsal column nuclei
and thalamus) in normal human subjects and in patients with dyspepsia following
instilling a liquid meal at a fixed rate into the stomach until maximal satiety, a
surrogate model of dyspepsia.
2. To measure fMRI signal in autonomic pathways (hypothalamus and amygdala) and in
endogenous analgesic pathways (periaqueductal gray/PAG) in normal human subjects and in
patients with dyspepsia using the above model.
3. To correlate physiological parameters (heart rate, skin conductance, respiratory rate)
to hedonic ratings (ratings on a visual analogue scale of satiety, nausea, bloating,
and pain) during the liquid meal stimulus in normal human subjects and patients with
dyspepsia.
In all these experiments we will correlate alterations in psychophysical measures which have
traditional measures of pain response (e.g., pain and other hedonic ratings, physiological
monitoring such as heart rate, etc) with the changes in fMRI signal in specific areas of the
brain.
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