Retired

Experimental neuromagnetism and biophysics

	Office 907 / (212) 998-7692 Mailing Address 4 Washington Place New York, NY 10003 Mail Box 042

Web links

www.cns.nyu.edu/associates/Williamson.html. Features: Web page at CNS(The Center for Neural Science).

Research

Using a large array of superconducting magnetic field sensors, it is now possible to characterize the time evolution of the human brain's magnetic field with a time resolution of milliseconds. Because the magnetic field emerges from the head without distortion, its pattern is more sharply localized than the pattern of accompanying electrical potential. We call this technique magnetic source imaging (MSI). It provides a means to establish the locations of neural activity with an accuracy of 5 mm and precision of 3 mm, thereby making it possible to define functional organizations such as the logarithmic tone map across the auditory cortex. These techniques also can be applied to locate magnetic foreign objects within the human body. Magnetic source imaging of the sources of spontaneous brain activity, such as the alpha rhythm, has been exploited to determine where these rhythmic signals are suppressed - thereby identifying the areas of the brain that are involved in cognitive tasks such as silent speech and mental imagery. The fine temporal resolution of MSI also reveals that the response of the auditory cortex to a tone establishes a memory, which subsequently decays exponentially with time. This lifetime is identical to how long an individual can remember the loudness of a sound (``echoic memory''), which represents the first time that a physiological measurement predicted a memory lifetime. Applying similar techniques to the human visual system, MSI revealed that each responding area of the cortical supports a memory function, and their lifetimes are organized in a hierarchy with lifetimes of a few hundred milliseconds in the sensory areas and from 10 to 30 seconds in the parietal, temporal, and prefrontal areas. Other research efforts in the Neuromagnetism Laboratory are directed toward mathematical developments of generalized inverse solutions, so that the recorded magnetic field pattern can be interpreted to define the distribution of cortical currents by an automatic procedure.

Publications

0. ``New High-Precision Photoelectric Universal Polarimeter and Birefringence Compensator'',
S. J. Williamson, J. M. Weingart, and R. D. Andrews,
J. Optical Society of America 54: 337-341 (1964).

1. ``Visually Evoked magnetic Fields of the Human Brain'',
D. . Brenner, S. J. Williamson, and L. Kaufman,
Science 190:480-482 (1975).

2. ``SQUID System for Detecting Evoked Magnetic Fields of the Human Brain'',
D. Brenner, S. J. Williamson, and L. Kaufman,
In: Low Temperature Physics-LT14,
M. Krusius and M. Vuorio, Eds.
(North Holland, Amsterdam, 1975) Vol. 4, pp. 266-269.

3. ``Application of a SQUID for Monitoring Magnetic Response of the Human Brain'',
D. Brenner, L. Kaufman, and S. J. Williamson,
IEEE Transactions on Magnetics MAG-13: 365-368 (1977).

4. ``Biomagnetism'',
S. J. Williamson, L. Kaufman, and D. Brenner,
In: Superconductor Applications: SQUIDs and Machines,
B. B. Schwartz and S. Foner, Eds . (Plenum, New York, 1977), pp. 355-404.

5. ``Magnetic Fields of the Human Brain'',
S. J. Williamson, L. Kaufman, and D. Brenner,
Naval Research Review 30: 1-18 (1977).

6. ``Somatically Evoked Magnetic Fields of the Human Brain'',
D. Brenner, J. Lipton, L. Kaufman, and S. J. Williamson,
Science 199: 81-83 (1978).

7. ``Applications of SQUID Detectors in Biomagnetism'',
S. J. Williamson and L. Kaufman,
In: Applications of Closed Cycle Cyrocoolers to Small Superconducting Devices,
J. E. Zimmerman and T. M. Flynn, Eds.
National Bureau of Standards Special Publication 508: 177-204 (1978).

8. ``Biomedical Applications of SQUIDs'',
S. J. Williamson, D. Brenner, and L. Kaufman,
In: Future Trends in Superconductive Electronics,
B. S. Deaver,Jr, C. M. Falco, J. H. Harris, and S. A. Wolf, Eds.
American Institute of Physics Conference Proceedings 44:106-116(1978).

9. ``Latency of the Neuromagnetic Response of the Human Visual Cortex'',
S. J. Williamson, L. Kaufman, and D. Brenner,
Vision Research 18: 107-110 (1978).

10. ``Biomagnetism and Vision'',
L. Kaufman and S. J. Williamson,
Investigative Ophthalmology & Visual Science 18-11: 1101-1103 (1978).

11. ``Evoked Neuromagnetic Fields of the Human Brain'',
S. J. Williamson, L. Kaufman, and D. Brenner,
Journal of Applied Physics 50: 2428-2421 (1979).

12. ``The Evoked Magnetic Fields of the Human Brain'',
L. Kaufman and S. J. Williamson,
In: Psychology: The Leading Edge,
F. L. Denmark, Ed. ,
Annals of the New York Academy of Sciences 30:45-65 (1980)

13. ``Le Magnetism du Cerveau'',
S. J. Williamson and L. Kaufman,
La Recherche 112, 722-724 (1980).

14. ``Magnetic Fields of the Human Brain'',
S. J. Williamson and L. Kaufman,
Journal of magnetism and Magnetic Materials 15-18: 1548-1550 (1980).

15. ``Magnetic Fields of the Cerebral Cortex'',
S. J. Williamson and L. Kaufman,
In: Biomagnetism,
S. N. Erne', H. D. Hahlbohm and H. Lu"bbig, Eds. (Walter de Gruyter, Berlin, 1981), pp. 353-402.

16. ``Evoked Magnetic Fields Reveal Different Visual Areas in Human Cortex'',
D. Brenner, Y. Okada, E. Maclin, S. J. Williamson and L. Kaufman,
In: Biomagnetism,
S. N. Erne', H. D. Hahlbohm and H. Lu"bbig, Eds.
(Walter de GruyLer, Berlin, 1981), pp. 432-444.

17. ``Application of a SQUID to Measurement of Somatically Evoked Fields: Transient Responses to Electrical Stimulation of the Median Nerve. '',
Y. Okada, L. Kaufman, D. Brenner, and S. J. Williamson,
In: Biomagnetism, S. N. Erne', H. D. Hahlbohm and H. Lu"bbig, Eds.
(Walter de Gruyter, Berlin, 1981), pp. 446-456.

18. ``Susceptometer for In Vivo Measurements of Iron Stored in Human Tissue'',
C. M. Bastuschack, D. Brenner, S. J. Williamson, and L. Kaufman,
In: Biomagnetism, S. N. Erne', H. D. Hahlbohm and H. Lu"bbig, Eds.
(Walter de Groyter, Berlin, 1981), pp. 446-456.

19. ``AC susceptibility Measurements with a Biomedical SQUID System'',
C. M. Bastuscheak and S. J. Williamson,
Physica 107B: 27-28 (1981).

20. ``Biomagnetism'',
S. J. Williamson and L. Kaufman,
Journal of Magnetism and Magnetic Materials 22: 129-201 (1981).

21. ``On the Relation between somatic Evoked Potentials and Fields'',
L. Kaufman, Y. Okada, D. Brenner and S. J. Williamson, International Journal of Neuroscience 15: 223-239 (1981).

22. ``Tonotopic Organization of the Human Auditory Cortex'',
G. L. Romani, S. J. Williamson and L. Kaufman Science 216: 1339-1340 (1982).

23. ``Magnetic Field of the Human Sensorimotor Cortex'',
Y. C. Okada, S. J. Williamson and L. Kaufman, International Journal of Neuroscience 17: 33-38 (1982).

24. ``Modulation Transfer Functions of the Human Visual System Revealed by Magnetic Field Measurements'',
Y. C. Okada, L. Kaufman, D. Brenner, and S. J. Williamson, Vision Research 22: 319-333 (1982).

25. ``Characterization of the Human Auditory Cortex by the Neuromagnetic Method'',
G. L. Romani, S. J. Williamson, L. Kaufman and D. Brenner, Experimental Brain Research 47: 381-393 (1982).

26. ``Magnetic Location of Cortical Activity'',
L. Kaufman and S. J. Williamson, In: Evoked Potentials, I. Bodis-Wollner Ed. , Annals of the New York Academy of Science 388: 197-213 (1982).

27. ``Biomagnetic Instrumentation'',
G. L. Romani, S. J. Williamson and L. Kaufman,
Review of Scientific Instruments 53: 1815-1845 (1982).

28. ``Application of SQUID Sensors to the Investigation of Neural Activity of the Brain"
S. J. Williamson and L. Kaufman,
IEEE Transactions on Magnetics MAG-19: 835-844 (1983).

29. ``The Hippocampal Formation as a Source of the Slow Endogenous Potentials'',
Y. C. Okada, L. Kaufm-an and S. J. Williamson,
Electroencepholography and clinical Neurophysiology 55: 417-426(1983).

30. ``Comments on a Commentary: A Reply to Stowell'',
L. Kaufman, Y. C. Okada, D. Brenner and S. J. Williamson International Journal of Neuroscience 18: 83-86 (1983).

31. Biomagnetism: an Interdisciplinary Approach S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds. NATO Advanced Study Institute Series A: Life Sciences 66 (Plenum Press, New York, 1983), 706 pages.

32. ``Perception and Event-Related Potentials and Fields'',
L. Kaufman In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 385-398.

33. ``Neurogenesis of Evoked Magnetic Fields'',
Y. C. Okada
In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 399-408.

34. ``Somatically Evoked Magnetic Field'',
Y. C. Okada In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 409-421.

35. ``Motor Field'',
Y. C. Okada In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 422-432.

36. ``Auditory Evoked Field'',
Y. C. Okada
In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 433-442.

37. ``Visual Evoked Field'',
Y. C. Okada
In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 443-459.

38. ``Endogenous Evoked Field'',
Y. C. Okada
In: Biomagnetism: an Interdisciplinary Approach,
S. J. Williamson, G. L. Romani, L. Kaufman, and I. Modena, Eds.
(Plenum Press, New York, 1983), pp. 460-468.

39. ``Inferences Concerning Anatomy and Physiology of the Human Brain Based on Its Magnetic Field'',
Y. C. Okada
Il Nuovo Cimento 2D: 379-409 (1983).

40. ``Retinotopic Map on the Visual Cortex for Eccentrically Placed Patterns: First Noninvasive Measurement'',
E. Maclin, Y. C. Okada, L. Kaufman, and S. J. Williamson
Il Nuovo Cimento 2D: 410-419 (1983).

41. ``Effect of Sample and Superconducting Shield Dimensions on the Flux Detected by a SQUID Magnetometer'',
D. P. Osterman and S. J. Williamson
Review of Scientific Instruments 54: 1380-1382 (1983).

42. ``Somatotopic Organization of the Human Somatosensory Cortex Revealed by Neuromagnetic Measurements'',
Y. C. Okada, R. Tanenhaum, S. J. Williamson and L. Kaufman
Experimental Brain Research 56: 197-305 (1984).

43. ``Magnetoencephalography with an Array of SQUID Sensors'',
S. J. Williamson, M. Pelizzone, Y. Okada, L. Kaufman, D. B. Crum and J. R. Maraden
In: Proceedings of the Tenth International Cryogenic Engineering Conference-ICEC10,
H. Collan, P. Berglund, and M. Krusius, Eds.
(Butterworth, Guildford, Surroy, 1984), pp. 339-348.

44. ``Different Sources of Transient and Steady-State Responses in Human Auditory Cortex Revealed by Neuromagnetic Fields'',
M. Pelizzone, S. J. Williamson, L. Kaufman, and K. L. Schafer Annals of New York Academy of Science 435: 570-571 (1984).

45. ``Evoked Neuromagnetic Fields'',
L. Kaufman, Y. Okada, J. Tripp, and H. Weinberg In: Brain and Information: Event-Related Potentials, R. Karrer, J. Cohen, and P. Tueting, Eds. Annals of New York Academy of Science 425: 722-742 (1984).

46. Biomagnetism: Applications and Theory Proceedings of the Fifth World Congress on Biomagnetism, Vancouver, Canada, H. Weinberg, G. Stroink, and T. Katila, Eds. , Pergamon Press, New York, 1985.

47. ``Five Channel SQUID Installation for Unshielded Neuromagnetic Measurements'',
S. J. Williamson, M. Pelizzone, Y. Okada, L. Kaufman, D. B. Crum, and J. R. Mareden,
In: Biomagnetism: Applications and Theory,
H. Weinherg, G. Stroink, and T. Katila, Eds. (Pergamon Press, New York, 1985), pp. 46-51.

48. ``Discrimination of Localized and Distributed Current Dipole Sources and Localized Single and Multiple Sources'',
Y. Okada, In:Biomagnetism: Applications and Theory, H. Weinberg, G. Stroink, and T. Katila, Eds. (Pergamon Press, New York, 1985), pp. 266-272.

49. ``Visually Evoked Responses from Non-Occiptial Areas of Human Cortex'',
O. V. Lounasmaa, S. J. Williamson, L. Kaufman, and R. Tanenbaum, In: Biomagnetism: Applications and Theory, H. Weinherg, G. Stroink, and T Katila, Eds. (Pergamon Press, New York, 1985), pp. 348-353.

50. ``Evidence for Multiple Areas in the Human Auditory Cortex'',
M. Pelizzone, S. J. Williamson, L. Kaufman and Y. Okada, In:Biomagnetism: Applications and Theory, H. Weinberg, G. Stroink, and T. Katila,Eds. (Pergamon Press, New York, 1985), pp. 326-330.

51. ``Frontiers in the New Science of Biomagnetism'',
S. J. Williamson and L. Kaufman Y. Okada, In:Biomagnetism: Applications and Theory, H. Weinberg, G. Stroink, and T. Katila,Eds. (Pergamon Press, New York, 1985), pp. 471-490.

52. ``Technique for Measuring the AC Susceptibility of Portions of the Human Body or Other Large Objects'',
C. M. Bastuscheck and S. J. Williamson Journal of Applied Physics 58:38963906 (1985).

53. ``The Neuromagnetic Field'',
L. Kaufman and S. J. Williamson
In: Evoked Potentials, Frontiers of Clinical Neuroscience, Vol. 3.
R. Q. Craceo and I. Bodis-Wollner, Eds.
(Alan R. Liss, New York, 1986), pp. 85-98.

54. ``Modulation of Auditory Evoked Magnetic Fields by Benzodiazopines'',
C. M. Sinton, J. R. McCullough, R. J. Ilmoniemi, and P. E. Etienne
Neurogsychobiology 16:215-218 (1986).

55. ``Introduction to Cerebral Modeling'',
In: Advances in Functional Localization --
"A Challenge for Biomagnetism''
World Scientific, New Jersey, pp. 122-145 (1986).

56. [Deleted]

57. ``Analysis of Neuromagnetic Signals'',
S. J. Williamson and L. Kaufman
In: Handbook of Electroencephalography and Clinical Neurophysiology,
Revised Volume l:Methods of Analysis of Brain Electric and Magnetic Signals, A. Givens and A. Re'mond, Eds.
(Elsevier, Amsterdam, 1987), pp. 405-448.

58. ``Source Localization of Long Latency Auditory Evoked Magnetic Fields in Human Temporal Cortex'',
D. L. Arthur, E. R. Flynn, and S . J. Williamson,
Electroencephalogrophy and clinical Neurophysiology Suppl. 40, 429-439 (1987).

59. ``Recent Developments in Neuromagnetism'',
L. Kaufman and S. J. Williamson In: Evoked Potentials III, C. Barber and T. Blum, Eds. (Buttorworths, Boston, 1987), pp. 100-113.

60. ``Analysis of the Magnetic Alpha Rhythm in Signal Space'',
R. J. Ilmoniemi and S. J. Williamson
Society of Neuroscience Abstracts 13:46 (1987).

61. ``Neuromagnetism: A Window on the Brain'',
S. J. Williamson and L. Kaufman
In: ELAN (Japan), January pp. 134-139; February pp. 148-151 (1988).

62. ``Magnetic Signs of Neural Activity'',
Physics Today: Physics News in 1988 Supplement, pp. S. 52-S. 53 (1988)

63. ``Instrumentation for Clinical Applications of Neuromagnetism'',
D. S. Buchanan, D. Paulson, and S . J. Williamson Advances in Cryogenic Engineering, Volume 33, R. W. Fast, Ed. (Plenum Press, New York, 1988), pp. 97-106.

64. ``Auditory Magnetic Fields'',
S. J. Williamson and L. Kaufman In: Physiology of the Ear, A. F. Jahn and J. R. Santos-Sacchi,Eds. (Raven Press, New York, 1988), pp. 497-505.

65. ''SQUID Arrays for Simultaneous Magnetic Measurements: Calibration and Source Localization Performance'',
P. Costa Ribairo, S. J. Williamson, and L. Kaufman IEEE Transactions on Biomedical Engineering 35: 551-560 (1988).

66. ``Method for Locating a Small Magnetic Object in the Human Body'',
R. J. IlÈ niemi, S. J. Williamson, L. Kaufman, H. Weinberg, and A. D. Boyd IEEE Transactions on Biomedical Engineering 35: 561-564 (1988)

67. ``Methods and Instrumentation for Biomagnetism'',
S. J. Williamson, S. E. Robinson, and L. Kaufman In: Biomagnetism 87, K. Atsumi, S. Ueno, T. Katila, and S. J. Williamson, Eds. (Tokyo Denki University Press, Tokyo, 1988), pp. 18-25.

68. ``Divided Attention Revisited: Selection Based on Location or Pitch'',
S. Curtis, L. Kaufman, and S. J. Williamson In: Biomagnetism `87, K. Atsumi, S. Ueno, T. Katila, and S. J. Williamson, Eds. (Tokyo Denki University Press, Tokyo, 1988), pp. 138-141.

69. ``New Method for the Study of Spontaneous Brain Activity'',
R. J. Ilmoniemi, S. J. Williamson, and W. E. HosteLler In: Biomagnetism `87, K. Atsumi, S. Ueno, T. Katila, and S. J. Williamson, Eds. (Tokyo Denki University Press, Tokyo, 1988), pp. 182-185.

70. ``Magnetic Localization of Neuronal Activity in the Human Brain'',
T. Yamamoto, S. J. Williamson, L. Kaufman, C. Nicholson, and R. Llinas Proceedings of the National Academy of Science USA 85: pp. 8732-8736 (1988).

71. ``Recent Developments in Neuromagnetism: Implications for Imaging'',
L. Kaufman and S. J. Williamson In: Functional Brain Imaging, G. Pfurtscheller and F. H. Lopez da Silva, Eds. (Hans Huber Publishers, Toronto, 1988), pp. 11-29.

72. ``Apparatus for Process for Making Biomagnetic Measurements'',
D. B. Crum, R C. Wesley, R. E. Greenblatt, R. M. Toussaint, E. C. Hirschkoff, L. Kaufman, and S. J. Williamson U. S. Patent Number: 4,793,355 December 27,1988.

73. ``Advances in Biomagnetism'',
S. J. Williamson, M. Hoke, G. Stroink, and M. Kotani, Eds. Plenum, New York (1989) 771 pages.

74. ``Introduction to Cerebral Modeling'',
S. J. Williamson In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism S. N. Erne' and G. L. Romani, Eds. (World Scientific, Singapore, 1989), pp. 121-145.

75. ``Neuromagnetic Measurements of Visual Responses to Chromaticity and Luminance'',
J. Krauskopf, G. Klemic, O. V. Lounasmaa, D. Travis , L. Kaufman, and S. J. Williamson
In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism
S. N. Erne' and G. L. Romani, Eds.
(World Scientific, Singapore, 1989), pp. 209-212.

76. ``Brain Activity Related to Spatial Visual Attention'',
B. Cuber, L. Kaufman, and S. J. Williamson
In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism
S. N. Erne' and G. L. Romani, Eds.
(World Scientific, Singapore, 1989), pp. 213-216.

77. ``Alpha Suppression Related to a Cognitive Task'',
B. J. Schwertz, C. Salustri, L. Kaufman, and S. J. Williamson In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism S. N. Erne' and G L. Romani, Eds (World Scientific, Singapore, 1 989), pp. 237240.

78. ``Differences in Alpha Suppression by Visualing and Rhyming'',
L. Kaufman, M. Glanzar, Y. M. Cycowiez, and S. J. Williamson In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism S. N. Erne' and G. L. Romani, Eds. (World Scientific, Singapore, 1989), pp. 241-244.

79. ``Method for Locating Sources of Human Alpha Activity'',
S. J. Williamson, J. -Z. Wang, and R. J. Ilmoniemi In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism S. N. Erne' and G. L. Romani, Eds. (World Scientific, Singapore, 19 89), pp. 257260.

80. ``Sequential Spatially Distributed Activity of the Human Brain Detected Magnetically by CroSQUIDs'',
G. A. Klemic, D. S. Buchanan, Y. M. Cycowiez, and S. J. Williamson
In: Advances in Biomagnetism - Functional Localization: A Challenge for Biomagnetism
S. N. Erne' and G. L. Romani, Eds.
(World Scientific, Singapore, 1989), pp. 285-288.

81. ``Advances in Neuromagnetic Instrumentation and Studies of Spontaneous Brain Activity'',
S. J. Williamson and L. Kaufman Brain,
Topography 2: 129-139 (1989).

82. ``Neuromagnetic Localization of Neuronal Activity in Visual and Extra-Visual Cortex'',
S. J. Williamson and L. Kaufman
In: Vision and the Brain: The Organization of the Central Visual System, Volume 67
B. Cohen, Ed. , (Raven Press, New York, 1990), pp. 271-287.

83. ``Theory of Neuroelectric and Neuromagnetic Fields'',
S. J. Williamson and L. Kaufman In: Advances In Audiology, Vol. 6; Auditory Electric and Magnetic Fields F. Grandori, M. Hoke, and G. L. Romani, Eds. (Karger, Basel, 1990), pp. 1-39.

84. ``Responses to Steady-State Auditory Stimulation'',
L. Kaufman and S. J. Williamson In: Advances In Audiology, Vol. 6; Auditory Electric and Magnetic Fields F. Grandori, M. Hoke, and G. L. Romani, Eds. (Karger, Basel, 1990), pp. 283-312.

85. ``Modulation of Spontaneous Brain Activity During Mental Imagery'',
L. Kaufman, B. Schwartz, C. Salustri, and S. J. Williamson Journal Cognitive Neuroscience 2: 124-132 (1990).

99. ``Changes in Cortical Activity When Subjects Scan Memory for Tones'',
L. Kaufman, S. Curtis, J. -Z. Wang, and S. J. Williamson Electroencephalography and clinical Neurophysiology 82: 2662B4 (1992).

100. ``Identifying Cortical Sources of Incoherent Fields of the Human Brain'',
L. Kaufman, J. -Z. Wang, and S. J. Williamson Proceedings of the 14th Annual International Conference of the IEEE Engineering In Medicine and Biology Society, J. P. Morucci, R. Plonsay, J. L. Coatrieux, and S. Laxminarayan, Eds. IEEE Engineering in Medicine and Biology Society (Piscataway, NJ) Satellite Symposium on Neuroscience and Technology, Vol. 14, pp. 1760-1762 (1992).

101. ``A Unique Inverse Estimate of Magnetic Source Images: The Minimum-Norm Least-Squares Approach'',
J. -Z. Wang, L. Kaufman, and S. J. Williamson Proceedings of the 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society,
J. P. Morucci, R. Plonsay, J. L. Coatrieux, and S. Laxminarayan, Eds. IEEE Engineering in Medicine and Biology Society (Piscataway, NJ) Satellite Symposium on Neuroscience and Technology, Vol. 14, pp. 1763-1765 (1992).

102. ``Representations of Isocontours on a Spherical Head'',
A. C. Bruno and S. J. Williamson Proceedings of the 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society,
J. P. Morucci, R. Plonsay, J. L. Costrieux, and S. Laxminarayan, Eds. IEEE Engineering in Medicine and Biology Society (Piscataway, NJ) Satellite Symposium on Neuroscience and Technology, Vol. 14, pp. 2174-2175 (1992).

103. ``On the Power of Spontaneous Brain Activity'',
L. Kaufman, S. J. Williamson, and J. -Z. Wang Proceedings of the 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society,
J. P. Morucci, R. Plonsey, J. L. Coatrieux, and S. Laxminarayan, Eds. IEEE Engineering in Medicine and Biology Society (Piscataway, NJ) Satellite Symposium on Neuroscience and Technology, Vol. 14, pp. 90-93 (1992).

104. ``Neuronal Sources of Parieto-occipital Alpha Rhythm'',
Z. -L. Lu, J. -Z. Wang, and S. J. Williamson In: Biomagnetism:clinical Aspects, M. HoLe, S. N. Erne', Y. C. Okada, and G. -L. Romani, Eds. Excerpta Medica, Elsevier, Amsterdam, pp. 33-37 (1992).

105. ``Changes in Cortical Activity When Subjects Scan Memory for Tones'',
L. Kaufman, S. Curtis, J. -Z. Wang, and S. J. Williamson In: Biomagnetism:clinical Aspects, M. P. oLe, S. N. Erne', Y. C. Okada, and G. -L. Romani, Eds. Excerpta Medica, Elsavier, Amesterdam, pp. 189-193 (1992).

106. ``Simulation of Activity of Visual Cortex'',
J. -Z. Wang, L. Kaufman, and J. H. Kaufman In: Biomagnetism:clinical Aspects, M. Hoke, S. N. Erne', Y. C. Okada, and G. -L. Romani, Eds. Excerpta Medica, Elsavier, Amsterdam, pp. 723-727 (1992).

107. ``Imaging Regional Changes in the Spontaneous Activity of the Brain: An Extension of the Minimum-Norm Least-Squares Estimate'',
J. -Z. Wang, L. Kaufman, and J. H. Kaufman Electroencephalography and clinical Neurophysiology 86: 36-50 (1993).

108. ``Minimum-Norm Least-Squares Estimation: Magnetic Source Images for a Spherical Head'',
J. -Z. Wang IEEE Transactions on Biomedical Engineering 40: 387-396 (1993).

109. ``Magnetic Source Imaging Basal on the Minimum-Norm Least-Squares Inverse'',
J. -Z. Wang, S. J. Williamson, and L. Kaufman Brain Topography 5; 365-371 (1993).

110. ``The Future of the EEG and MEG'',
J. P. Wikswo,Jr. , A. Gevins, and S. J. Williamson Electroenaephalography and clinical Neurophysiology 87: 1-9 (1993).

111. ``MNLS Inverse Discriminates Between Neuronal Activity on Opposite Walls of a Simulated Sulcus of the Brain'',
J. -Z. Wang IEEE Transactions on Biomedical Engineering 41: 470-479 (1993).

112. ``Duration of EEG and MEG alpha Suppression Increases with Angle in a Mental Rotation Task'',
C. M. Michel, L. Kaufman, and S. J. Williamson J. Cognitive Neuroscience 6: 139-149 (1994).

113. ``Tonotopic Organization of Human Auditory Association Cortex'',
S. Cansino, S. J. Williamson, and D. Karron Brain Research 663: 38-50 (1994).

114. ``Kinetic Images of Neuronal Activity of the Human Brain Based on the MNLS Inverse" J. Z. Wang, S. J. Williamson, and L. Kaufman Brain Topography 7: 193-200 (1995).

115. ``Habituation Characterizes Auditory Sensory Memory'',
S. J. Williamson and Z. -L. Lu
In: Quantitative and Topological EEG and PEG Analysis,
M. Eiselt, U. Zwiener, and H. Witte, Eds.
Universita"tsverlag Druckhaus-Mayer GmhH, Jena, pp. 19-26 (1995).

116. ``Do Auditory Stimuli Activate Human Parietal Brain Regions?'',
M. Ha"ma"la"inen, R. Hari, O. V. Lounasmaa, and S. J. Williamson
Letters to the Editor, NeuroReport 6: 1712 (1995).

117. ``Biomagnetism: Fundamental Research and Clinical Applications, Proceedings of the 9th International Conference on Biomagnetism'',
Studies in Applied Electromagnetics and Mechanics, Vol. 7
C. Baumgartuer, L. Deocte, G. Stroink, and S. J. Williamson, Eds.
(Elsavier and IOS Presfi, Amterdam, 1995), 846 pages.

118. ``Support for the Alphon Hypothesis as a Description of Human Alpha in the MEG'',
Z. -L. Lu, J. -Z. Wang, D. Karron, and S. J. Williamson
``Biomagnetism: Fundamental Research and Clinical Applications, Proceedings of the 3th International Conference on Biomagnetism,''
Studies in Applied Electromagnetics and Mechanics, Vol. 7
C. Baumgartner, L. Deeake, G. Stroink, and S. J. Williamson, Eds.
(Elsavier and IOS Press, Amsterdam, 1995), pp. 296-298.

119. ``Spatio-Temporal Model of Neural Activity of the Human Brain Based on the MNLS Inverse'',
J. -Z. Wang, S. J. Williamson, and L. Kaufman ''Biomagnetism: Fundamental Research and Clinical Applications, Proceedings of the 9th International Conference on Biomag netism, Studies in Applied Electromagnetics and Mechanics, Vol. 7 C. Baumgar?ner, L. Deeake, G. Stroink, and S. J. Williamson, Eds. (Elsavier and IOS Press, Amsterdam, 1995), pp. 299301.

120. ``MNLS Inverse Applied to Complex Source Geometries'',
J. -Z. Wang, S. J. Williamson, and L. Kaufman ``Biomagnetism: Fundamental Research and Clinical Applications, Proceedings of the 9th International Conference on Biomagnetism, Studies in Applied Electromag netics and Mechanics, Vol. 7 C. Baumgaréner, L. Deeake, G. Stroink, and S. J. Williamson, Eds. (Elsavier and IOS Press, Amsterdam, 1995), pp. 394-397.

121. ``Electrical Impedance Tomography: Induced-Current Imaging Achieved with a Multiple Coil System'',
N. G. Genc,er, Y. Z. Ider, and S. J. Williamson IEEE Transactions on Biomedical Engineering 43:139-149 (1996).

122. ``Optimal Reference Electrode Selection for Electric Source Imaging' N. G. Genc,er, S. J. Williamson, and A. Gueziec Electroencephalography and clinical Neurophysiology 99: 163-173 (1996).

123. ``Generalized Inverse Solution for Bimodal Electro-Magnetic Source Images'',
N. G. Genc,er and S. J. Williamson In: Biomagnetism: Fundamental Research and Clinical Applications, Proceedings of the 10th International Conference on Biomagnetism xx-yy

124. ``Dynamic Organization of the Human Visual System Revealed by Lifetimes of Activation Traces'',
M. A. Uusitalo, S. J. Williamson, and M. T. Seppa". Neuroscience Letters 213: 149-152 (1996).

125. ''Neural Substrates of Working Memories are Revealed Magnetically by the Local Suppression of Alpha Rhythm'',
S. J. Williamson, L. Kaufman, S. Curtis, Z. -L. Lu, C. M. Michel, and J. -Z. Wang
In:Visualization of Information Processing in the Human Brain: Recent Advances in MEG And Functional MRI (EEG Suppl. 47).
Elsevier Science B. V. , The Netherlands, pp. 163-180 (1996).

126. ``Magnetic Sources Images of Human Brain Functions'',
N. G. Genc,er and S. J. Williamson Behavior Research Methods, Instrumentation L Computations 29: 78-83 (1997).

127. ``Study of the Human Occipital Alpha Rhythm: The Alphon Hypothesis and Alpha Suppression'',
S. J. Williamson, L. Kaufman, Z. -L. Lu, J. -Z. Wang, and D. Karron
International Journal of Psychophysics 26: 63-76 (1997).

128. ``Neuromagnetic Fields Reveal Cortical Plasticity When Learning An Auditory Discrimination Task'',
S. Cansino and S. J. Williamson
Brain Research 764: 53-66 (1997).

129. ``Magnetic Brain Imaging Traces a Stairway to Memory'',
J. Glanz (``Science'' writer) and S. J. Williamson
Science (Research News) 280: 37 (1998).

130. ``Differential Characterization of Neural Sources with the Bimodal Truncated SVD Pseudoinverse for EEG and MEG Measurements
N. G. Genc,er and S. J. Williamson
IEEE Transactions on Biomedical Engineering 45: 827-838 (1998).

131. ``Magnetic Source Imaging of the Human Brain Reveals Cortical Plasticity When Learning an Auditory Discrimination Task'',
S. Cansino and S. J. Williamson
Proceedings of the 11th International Conference on Biomagnetism, Sendai, Japan, in press (1999).

132. ``How Quickly We Forget: Magnetic Fields Reveal A Hierarchy of Memory Lifetimes in the Human Brain'',
S. J. Williamson
Science Spectra 15: 68-73 (1999).

133. ``The Lifetime of Human Visual Sensory memory Exhibits Plasticity, Being Prolonged by Practice and Shortened by Enhanced Luminance'',
W. Yang and S. J. Williamson, submitted (1999).

Textbooks:

``Fundamentals of Air Pollution'',
S. J. Williamson Addison-Wesley Publishing Company, 1973 Reading, Massachusetts 472 pages

``Light and Color in Nature and Art'',
S. J. Williamson and H. z. Cummins John Wiley & Sons, Inc. , 1983 New York, New York 488 pages