Behavioral and Neural Effects of High Magnetic Fields

Summary

Principal Investigator: THOMAS HOUPT
Abstract: DESCRIPTION (provided by applicant): Advances in magnetic resonance imaging (MRI) are driving the development of faster and higher resolution MRI machines. While MRI machines with static magnetic fields of 1 to 2 tesla (T) and resolutions of 2 mm3 are standard in clinical use, higher resolution requires stronger fields. Little is known about the sensory or physiological effects of static magnetic fields of high strength on mammals and humans. Using the large- bore, high-strength NMR magnets at the U.S. National High Magnetic Field Laboratory at Florida State University, we have discovered that exposure to 7T or higher magnetic fields has behavioral and neural effects on rats. At the behavioral level, magnetic field exposure induced a conditioned taste aversion after pairing with the taste of saccharin. At the neural level, the same exposure induced specific and significant c- Fos , a marker of neuronal activation, in the rat brainstem. c-Fos was observed in visceral and stress relays and in vestibular nuclei (e.g. the medial vestibular nucleus). Both the behavioral response and the pattern of c-Fos activation are similar to the effects of vestibular disturbance, such as rotation and motion sickness. In the previous funding period, labyrinthectomy was found to block all these effects;the specific inner ear organ responsible for magnetic field transduction is still unknown, however. Two other notable findings were: 1) preexposure to 14T reduces responsiveness upon later exposure, suggesting either sensory adaptation or damage;2) after rats are trained to climb a ladder through the 14T magnet, they not only refuse to traverse 14T on subsequent trials, but they will not cross the 2T field line. Here we propose: to explore the specific vestibular sites that transduce magnetic field reponses using using pharmacology and mutant mouse strains that lack otolith or semicircular organs;to define the parameters of preexposure that may distinguish adaptation from damage;and to determine the thresholds for aversion and detection using a) ladder-climbing through different magnetic fields and b) conditioned suppression with magnetic fields as the cue. This proposal is relevant to public health in two ways: First, patients undergoing MRI examinations are routinely exposed to high strength static magnetic fields of 3T, and higher strength MRI machines are in development. This proposal explores the effects of similar magnetic fields on the vestibular system that might cause acute motion sickness or long-term changes in vestibular function after repeated exposure. Secondly, vestibular dysfunction is a common complaint and cause of injury (e.g. falling in the elderly), and this proposal contains novel approaches to investigating the inner ear and vestibular system
Funding Period: 2000-07-17 - 2010-06-30
more information: NIH RePORT

Top Publications

  1. pmc Orientation within a high magnetic field determines swimming direction and laterality of c-Fos induction in mice
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, Florida and
    Am J Physiol Regul Integr Comp Physiol 305:R793-803. 2013
  2. pmc Head tilt in rats during exposure to a high magnetic field
    Thomas A Houpt
    Department of Biological Science, King Life Sciences Building, The Florida State University, Tallahassee, FL 32306 4295, United States
    Physiol Behav 105:388-93. 2012
  3. pmc Behavioral effects on rats of motion within a high static magnetic field
    Thomas A Houpt
    Department of Biological Science, King Life Sciences Building, 319 Stadium Drive, The Florida State University, Tallahassee, FL 32306 4295, United States
    Physiol Behav 102:338-46. 2011
  4. pmc c-Fos induction by a 14 T magnetic field in visceral and vestibular relays of the female rat brainstem is modulated by estradiol
    Angie M Cason
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306 4295, USA
    Brain Res 1347:48-57. 2010
  5. pmc Circular swimming in mice after exposure to a high magnetic field
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, King Life Sciences Building, 319 Stadium Drive, The Florida State University, Tallahassee, Florida 32306 4295, USA
    Physiol Behav 100:284-90. 2010
  6. pmc Repeated exposure attenuates the behavioral response of rats to static high magnetic fields
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306 4340, USA
    Physiol Behav 99:500-8. 2010
  7. pmc Interactions of temperature and taste in conditioned aversions
    Patrick L Smith
    Department of Psychology, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306, USA
    Physiol Behav 99:324-33. 2010
  8. ncbi Labyrinthectomy abolishes the behavioral and neural response of rats to a high-strength static magnetic field
    Angie M Cason
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, Florida 32306 4340, United States
    Physiol Behav 97:36-43. 2009
  9. pmc Rats avoid high magnetic fields: dependence on an intact vestibular system
    Thomas A Houpt
    Department of Biological Science, Biomedical Research Facility 209 MC 4340, The Florida State University, Tallahassee, FL 32306, USA
    Physiol Behav 92:741-7. 2007
  10. ncbi Evidence for a cephalic site of action of high magnetic fields on the behavioral responses of rats
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306 4340, United States
    Physiol Behav 92:665-74. 2007

Scientific Experts

  • THOMAS HOUPT
  • Angie M Cason
  • James C Smith
  • Patrick L Smith
  • Bumsup Kwon
  • Megan Denbleyker
  • Kimberly Ferrence

Detail Information

Publications12

  1. pmc Orientation within a high magnetic field determines swimming direction and laterality of c-Fos induction in mice
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, Florida and
    Am J Physiol Regul Integr Comp Physiol 305:R793-803. 2013
    ..g., the model of Roberts et al. of an induced Lorenz force causing horizontal canal cupula deflection)...
  2. pmc Head tilt in rats during exposure to a high magnetic field
    Thomas A Houpt
    Department of Biological Science, King Life Sciences Building, The Florida State University, Tallahassee, FL 32306 4295, United States
    Physiol Behav 105:388-93. 2012
    ....
  3. pmc Behavioral effects on rats of motion within a high static magnetic field
    Thomas A Houpt
    Department of Biological Science, King Life Sciences Building, 319 Stadium Drive, The Florida State University, Tallahassee, FL 32306 4295, United States
    Physiol Behav 102:338-46. 2011
    ..We conclude that, in rats, movement through the steep gradient of a high magnetic field has some behavioral effects, but sustained exposure to the homogenous center of the field is required for the full behavioral consequences...
  4. pmc c-Fos induction by a 14 T magnetic field in visceral and vestibular relays of the female rat brainstem is modulated by estradiol
    Angie M Cason
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306 4295, USA
    Brain Res 1347:48-57. 2010
    ..These results suggest that ovarian steroids may mediate sex differences in the behavioral responses to magnetic field exposure at the level of visceral and vestibular nuclei of the brainstem...
  5. pmc Circular swimming in mice after exposure to a high magnetic field
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, King Life Sciences Building, 319 Stadium Drive, The Florida State University, Tallahassee, Florida 32306 4295, USA
    Physiol Behav 100:284-90. 2010
    ..The transient deficits in swimming and posture seen shortly after magnet exposure are consistent with an acute perturbation of the vestibular system by the high magnetic field...
  6. pmc Repeated exposure attenuates the behavioral response of rats to static high magnetic fields
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306 4340, USA
    Physiol Behav 99:500-8. 2010
    ....
  7. pmc Interactions of temperature and taste in conditioned aversions
    Patrick L Smith
    Department of Psychology, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306, USA
    Physiol Behav 99:324-33. 2010
    ..These results demonstrate that temperature can serve as a salient cue in conditioned aversions that affect ingestion independent of taste cues or by potentiating taste cues...
  8. ncbi Labyrinthectomy abolishes the behavioral and neural response of rats to a high-strength static magnetic field
    Angie M Cason
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, Florida 32306 4340, United States
    Physiol Behav 97:36-43. 2009
    ..These results demonstrate that an intact inner ear is necessary for all the observed effects of exposure to high magnetic fields in rats...
  9. pmc Rats avoid high magnetic fields: dependence on an intact vestibular system
    Thomas A Houpt
    Department of Biological Science, Biomedical Research Facility 209 MC 4340, The Florida State University, Tallahassee, FL 32306, USA
    Physiol Behav 92:741-7. 2007
    ..The inner ear is a novel site for magnetic field transduction in mammals, but perturbation of the vestibular apparatus would be consistent with human reports of vertigo and nausea around high strength MRI machines...
  10. ncbi Evidence for a cephalic site of action of high magnetic fields on the behavioral responses of rats
    Thomas A Houpt
    Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306 4340, United States
    Physiol Behav 92:665-74. 2007
    ..Female rats responded similarly to male rats, although magnet-induced CTA appeared resistant to extinction in female rats...
  11. ncbi Sex and estrous cycle differences in the behavioral effects of high-strength static magnetic fields: role of ovarian steroids
    Angie M Cason
    Department of Biological Science, Program in Neuroscience, BRF 252 MC 4340, The Florida State University, Tallahassee, Florida 32306 4340, USA
    Am J Physiol Regul Integr Comp Physiol 290:R659-67. 2006
    ..Furthermore, female rats acquired a more persistent CTA than male rats, which was not dependent on estrous phase or endogenous ovarian steroids...
  12. ncbi Behavioral effects on rats of high strength magnetic fields generated by a resistive electromagnet
    Thomas A Houpt
    Department of Biological Science, The Florida State University, Tallahassee, FL 32306 4340, USA
    Physiol Behav 86:379-89. 2005
    ..Finally, the effects of exposure to 4 T are clinically relevant, as 4 T magnetic fields are commonly used in functional MRI assays...