Friday, July 26, 2013

Bioelectromagnetism: Principles and Applications of Bioelectric and Biomagnetic Fields

A good textbook about bioelectricity and biomagnetism is Bioelectromagnetism: Principles and Applications of Bioelectric and Biomagnetic Fields by Jaakko Malmivuo and Robert Plonsey (Oxford University Press, 1995). One of the best features of the book is that it is available for free online at www.bem.fi/book/index.htm. The book covers many of the topics Russ Hobbie and I discuss in Chapters 6-9 of the 4th edition of Intermediate Physics for Medicine and Biology: the cable equation, the Hodgkin and Huxley model, patch-clamp recordings, the electrocardiogram, biomagnetism, the bidomain model, and magnetic stimulation. The book’s Introduction outlines its eight parts:
Part I discusses the anatomical and physiological basis of bioelectromagnetism. From the anatomical perspective, for example, Part I considers bioelectric phenomena first on a cellular level (i.e., involving nerve and muscle cells) and then on an organ level (involving the nervous system (brain) and the heart).

Part II introduces the concepts of the volume source and volume conductor and the concept of modeling. It also introduces the concept of impressed current source and discusses general theoretical concepts of source-field models and the bidomain volume conductor. These discussions consider only electric concepts.

Part III explores theoretical methods and thus anatomical features are excluded from discussion. For practical (and historical) reasons, this discussion is first presented from an electric perspective in Chapter 11. Chapter 12 then relates most of these theoretical methods to magnetism and especially considers the difference between concepts in electricity and magnetism.

The rest of the book (i.e., Parts IV - IX) explores clinical applications. For this reason, bioelectromagnetism is first classified on an anatomical basis into bioelectric and bio(electro)magnetic constituents to point out the parallelism between them. Part IV describes electric and magnetic measurements of bioelectric sources of the nervous system, and Part V those of the heart.

In Part VI, Chapters 21 and 22 discuss electric and magnetic stimulation of neural and Part VII, Chapters 23 and 24, that of cardiac tissue. These subfields are also referred to as electrobiology and magnetobiology. Part VIII focuses on Subdivision III of bioelectromagnetism - that is, the measurement of the intrinsic electric properties of biological tissue. Chapters 25 and 26 examine the measurement and imaging of tissue impedance, and Chapter 27 the measurement of the electrodermal response.

In Part IX, Chapter 28 introduces the reader to a bioelectric signal that is not generated by excitable tissue: the electro-oculogram (EOG). The electroretinogram (ERG) also is discussed in this connection for anatomical reasons, although the signal is due to an excitable tissue, namely the retina.
Jaakko Malmivuo is a Professor in the School of Electrical Engineering at Aalto University in Helsinki, Finland. He is also the director of the Ragnar Granit Institute.

Robert Plonsey is the Pfizer-Pratt University Professor Emeritus of Biomedical Engineering at Duke University. This year, he received the IEEE Biomedical Engineering Award “for developing quantitative methods to characterize the electromagnetic fields in excitable tissue, leading to a better understanding of the electrophysiology of nerve, muscle, and brain.” Plonsey is cited on 16 pages of Intermediate Physics for Medicine and Biology, the most of any scientist or author.

2 comments:

  1. Can't wait for another online course in bioelectricity.

    I would like to know how the capacitance of peripheral nervous tissue--myelinated and unmyelinated--changes with frequency of applied field up to about 50kHz.

    Any thoughts about where I might find this data, and/or how one would would measure it directly?

    Thanks in advance for your thoughts?

    ReplyDelete
  2. It depends on how you measure it. See my chapter in the Biomedical Engineering Handbook:

    Roth, B. J., 2006, The electrical conductivity of tissues. in: Biomedical Engineering Fundamentals: The Biomedical Engineering Handbook, 3rd Edition. Bronzino, J. D., Eds., CRC, Boca Raton, FL, chapter 21.

    I can send pdf if you email me (roth@oakland.edu)

    ReplyDelete