Limitations of ex vivo measurements for in vivo neuroscience

Alexander Opitz, Arnaud Falchier, Gary S. Linn, Michael P. Milham, Charles E. Schroeder

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


A long history of postmortem studies has provided significant insight into human brain structure and organization. Cadavers have also proven instrumental for the measurement of artifacts and nonneural effects in functional imaging, and more recently, the study of biophysical properties critical to brain stimulation. However, death produces significant changes in the biophysical properties of brain tissues, making an ex vivo to in vivo comparison complex, and even questionable. This study directly compares biophysical properties of electric fields arising from transcranial electric stimulation (TES) in a nonhuman primate brain pre- and postmortem. We show that pre- vs. postmortem, TES-induced intracranial electric fields differ significantly in both strength and frequency response dynamics, even while controlling for confounding factors such as body temperature. Our results clearly indicate that ex vivo cadaver and in vivo measurements are not easily equitable. In vivo examinations remain essential to establishing an adequate understanding of even basic biophysical phenomena in vivo.

Original languageEnglish (US)
Pages (from-to)5243-5246
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number20
StatePublished - May 16 2017


  • Biophysical
  • Electric field
  • Nonhuman primate


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