Project: Research project

Project Details


Positron emission tomography (PET) provides non-invasive, quantitative, in
vivo, measurements of regional cerebral blood flow (rCBF) and regional
cerebral metabolic rate (rCMR) in man. Regional CBF and CMR vary directly
with the regional rate of cerebral neuronal activity in the brain. Oxygen
15-H2O PET is a new PET methodology employing oxygen 15 in water (oxygen 15
half life = 123 sec) as a diffusible blood flow tracer to measure rCBF.
Oxygen 15-H2O PET is uniquely suited to the study of focal cerebral
function because of the brief (40 sec) scan duration, good resolution and
the capacity for rapidly sequential scans (8 rCBF scans in 90 min) in a
single individual. We propose to use oxygen 15-H2O PET to measure rCBF in normal volunteers
during maneuvers designed to induce focal activations of discrete, cortical
neuron populations. Initial studies will delineate response
characteristics of somatic sensory neurons to electrocutaneous stimuli
ranging in frequency from slow (2-10 Hz) to flutter (40-80 Hz) to vibration
(100-500 Hz). Stimulus frequencies are chosen on the basis of the known
response characteristics of cortical somatic sensory neurons in primates.
When stimuli inducing consistent cortical rCBF responses are defined, they
will be employed for more complex stimulus paradigms. Complex paradigms
will be intended to induce focal cortical changes via cognitive tasks
including pattern recognition, directed attention and language, all using
somatic sensory stimuli as the vehicle. In this way the activation induced
by the simple stimuli themselves will be well known, allowing
discrimination of the regional changes due to the higher-order cognitive
activity from rCBF change due to the stimulus alone. These experiments will provide a foundation for continued work on human
cortical neurophysiology with the long-range intent of exploring
progressively more complex human behaviors. Precise quantitation of the
cortical CBF changes induced by simple, reproducible stimuli will also be
the basis for studies of neurological pathophysiology, as these stimuli may
then be used to generate cortical activation in individuals with
neurological disease.
Effective start/end date7/1/846/30/89


  • National Institutes of Health


  • Medicine(all)
  • Neuroscience(all)


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