Local and distant responses to single pulse electrical stimulation reflect different forms of connectivity
Britni Crocker,
Lauren Ostrowski,
Ziv M. Williams,
Darin D. Dougherty,
Emad N. Eskandar,
Alik S. Widge,
Catherine J. Chu,
Sydney S. Cash,
Angelique C. Paulk
Affiliations
Britni Crocker
Harvard-MIT Health Sciences and Technology, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, 02139; Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
Lauren Ostrowski
Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
Ziv M. Williams
Nayef Al-Rodhan Laboratories, Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
Darin D. Dougherty
Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
Emad N. Eskandar
Nayef Al-Rodhan Laboratories, Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Department of Neurosurgery, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY 10467
Alik S. Widge
Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129; Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA 02124; Department of Psychiatry, University of Minnesota, Minneapolis, MN 55455
Catherine J. Chu
Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
Sydney S. Cash
Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA; Corresponding author.
Angelique C. Paulk
Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA; Nayef Al-Rodhan Laboratories, Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Corresponding author.
Measuring connectivity in the human brain involves innumerable approaches using both noninvasive (fMRI, EEG) and invasive (intracranial EEG or iEEG) recording modalities, including the use of external probing stimuli, such as direct electrical stimulation. To examine how different measures of connectivity correlate with one another, we compared ‘passive’ measures of connectivity during resting state conditions to the more ‘active’ probing measures of connectivity with single pulse electrical stimulation (SPES). We measured the network engagement and spread of the cortico-cortico evoked potential (CCEP) induced by SPES at 53 out of 104 total sites across the brain, including cortical and subcortical regions, in patients with intractable epilepsy (N=11) who were undergoing intracranial recordings as a part of their clinical care for identifying seizure onset zones. We compared the CCEP network to functional, effective, and structural measures of connectivity during a resting state in each patient. Functional and effective connectivity measures included correlation or Granger causality measures applied to stereoEEG (sEEGs) recordings. Structural connectivity was derived from diffusion tensor imaging (DTI) acquired before intracranial electrode implant and monitoring (N=8). The CCEP network was most similar to the resting state voltage correlation network in channels near to the stimulation location. In contrast, the distant CCEP network was most similar to the DTI network. Other connectivity measures were not as similar to the CCEP network. These results demonstrate that different connectivity measures, including those derived from active stimulation-based probing, measure different, complementary aspects of regional interrelationships in the brain.
