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J Neurosci Methods. 2017 Feb 1;277:101-112. doi: 10.1016/j.jneumeth.2016.12.014. Epub 2016 Dec 21.

Mapping effective connectivity in the human brain with concurrent intracranial electrical stimulation and BOLD-fMRI.

Author information

1
Department of Neurosurgery, Human Brain Research Laboratory, University of Iowa, Iowa City, IA 52241, USA. Electronic address: hiroyuki-oya@uiowa.edu.
2
Department of Neurosurgery, Human Brain Research Laboratory, University of Iowa, Iowa City, IA 52241, USA.
3
Department of Radiology, University of Iowa College of Medicine, Iowa City, IA 52241, USA.
4
Department of Electrical and Computer Engineering, University of Iowa College of Engineering, USA.
5
Institute of Neuroscience, Newcastle University, Newcastle, UK.
6
UCL Institute of Neurology, University College London, London, UK.
7
UCL Institute of Child Health, University College London, London, UK.
8
Division of Biology and Biological Engineering, California Institute of Technology, USA.

Abstract

BACKGROUND:

Understanding brain function requires knowledge of how one brain region causally influences another. This information is difficult to obtain directly in the human brain, and is instead typically inferred from resting-state fMRI.

NEW METHOD:

Here, we demonstrate the safety and scientific promise of a novel and complementary approach: concurrent electrical stimulation and fMRI (es-fMRI) at 3T in awake neurosurgical patients with implanted depth electrodes.

RESULTS:

We document the results of safety testing, actual experimental setup, and stimulation parameters, that safely and reliably evoke activation in distal structures through stimulation of amygdala, cingulate, or prefrontal cortex. We compare connectivity inferred from the evoked patterns of activation with that estimated from standard resting-state fMRI in the same patients: while connectivity patterns obtained with each approach are correlated, each method produces unique results. Response patterns were stable over the course of 11min of es-fMRI runs. COMPARISON WITH EXISTING METHOD: es-fMRI in awake humans yields unique information about effective connectivity, complementing resting-state fMRI. Although our stimulations were below the level of inducing any apparent behavioral or perceptual effects, a next step would be to use es-fMRI to modulate task performances. This would reveal the acute network-level changes induced by the stimulation that mediate the behavioral and cognitive effects seen with brain stimulation.

CONCLUSIONS:

es-fMRI provides a novel and safe approach for mapping effective connectivity in the human brain in a clinical setting, and will inform treatments for psychiatric and neurodegenerative disorders that use deep brain stimulation.

KEYWORDS:

Amygdala; DBS; Effective connectivity; Electrical stimulation; Functional MRI; Human

PMID:
28012852
PMCID:
PMC5534177
DOI:
10.1016/j.jneumeth.2016.12.014
[Indexed for MEDLINE]
Free PMC Article

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