Safe electrical stimulation of the cochlear nerve at the promontory during functional magnetic resonance imaging

Obler, R; Köstler, Herbert; Weber, Benno; Mack, K. F.; Becker, H.

doi:10.1002/(sici)1522-2594(199908)42:2<371::aid-mrm19>3.0.co;2-3

Cited by 21 publications

(12 citation statements)

References 28 publications

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“…This is clearly demonstrated in Figure 4, and is equally evident in the IR-EPI images of Figure 5, where there is no distortion evident in the right temporal lobe, despite the presence of the transtympanic electrode in the right ear. This is in marked contrast to studies in which a local current source is used, where information from much of the ipsilateral cortex is lost (9). This is especially unfortunate, given the interesting preliminary findings concerning the lateralization of auditory responses in deaf subjects (see below).…”

Section: Discussionmentioning

confidence: 92%

“…A preliminary study by the team that published the earlier PET studies served to demonstrate the feasibility of the fMRI approach, but was restricted to single-slice acquisition at modest (15 seconds) temporal resolution (7), and did not address the potential hazards associated with electrical stimulation (8). A safe, MR-compatible method for electrical stimulation at the promontory has been developed, based on a fiber-optic connection from a commercial promontory stimulator and a local battery-powered current source supplying the needle electrode (9). Unfortunately, the current source, which is attached to the subject's head, results in a large signal void covering much of the ipsilateral frontal region.…”

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confidence: 99%

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A method for the direct electrical stimulation of the auditory system in deaf subjects: A functional magnetic resonance imaging study

Alwatban

Ludman

Mason

et al. 2002

Magnetic Resonance Imaging

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Purpose: To develop a safe functional magnetic resonance imaging (fMRI) procedure for auditory assessment of deaf subjects. Materials and Methods:A gold-plated tungsten electrode has been developed which has zero magnetic susceptibility. Used with carbon leads and a carbon reference pad, it enables safe, distortion-free fMRI studies of deaf subjects following direct electrical stimulation of the acoustic nerve. Minor pickup of the radio frequency (RF) pulses by the electrode assembly is difficult to eliminate, and a SPARSE acquisition sequence is used to avoid any effects of unintentional auditory nerve stimulation. Results:The procedure is demonstrated in a deaf volunteer. Activation is observed in the contralateral but not the ipsilateral primary auditory cortex. This is in sharp contrast to studies of auditory processing in hearing subjects, but consistent with the small number of previous positron emission tomography (PET) and MR studies on adult deaf subjects. Conclusion:The fMRI procedure is able to demonstrate whether the auditory pathway is fully intact, and may provide a useful method for preoperative assessment of candidates for cochlear implantation.

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Section: Discussionmentioning

confidence: 92%

mentioning

confidence: 99%

A method for the direct electrical stimulation of the auditory system in deaf subjects: A functional magnetic resonance imaging study

Alwatban

Ludman

Mason

et al. 2002

Magnetic Resonance Imaging

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“…The recent use of deep brain electrical stimulation in human fMRI studies shows that it should be possible to perform safe functional MR imaging by modifying not only the tip region of the electrode, but also the arrangement of the electrodes, connecting wires, and coil (Gleason et al, 1992;Berthezene et al, 1997;Obler et al, 1999;Tronnier et al, 1999;Alwatban et al, 2002;Rezai et al, 2002). One of the concerns about MR compatibility is the interaction between the electrode and the time-varying magnetic field in the presence of a conducting loop (Tenforde, 1986).…”

Section: Electrode Interferencementioning

confidence: 99%

“…In our experimental set-up, the induced current was minimized by decreasing the area of the conducting loop, and the conducting loop was arranged approximately parallel to the B1 field and so should induce a lower voltage within the RF field. In addition, the impedance of the carbon fiber electrode was approximately 1 M , higher than those for conventional electrodes, making it possible to reduce the induced electrical current (Obler et al, 1999).…”

Section: Electrode Interferencementioning

confidence: 99%

“…Visual targeting of the electrode location using magnetic resonance imaging (MRI) has been shown to be effective in shortening the time required for implantation and, because of its accuracy, in improving the clinical symptoms (Starr et al, 2002;Patel et al, 2003). Several MR-compatible electrical stimulation methods for use in humans have been developed (Dormont et al, 1997;Liem and van Dongen, 1997;Obler et al, 1999;Rezai et al, 2001), but the interference elicited by metal electrodes in a strong magnetic field is still a potential problem in functional MRI (fMRI) studies, in which susceptibility artifacts may result in image degradation (Berthezene et al, 1997;Obler et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

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A method for direct thalamic stimulation in fMRI studies using a glass-coated carbon fiber electrode

Shyu

Lin

Sun

et al. 2004

Journal of Neuroscience Methods

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BOLD response to direct thalamic stimulation reveals a functional connection between the medial thalamus and the anterior cingulate cortex in the rat

Shyu

Lin

Sun

et al. 2004

Magnetic Resonance in Med

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Recent functional neuroimaging studies in humans and rodents have shown that the anterior cingulate cortex (ACC) is activated by painful stimuli, and plays an important role in the affective aspect of pain sensation. The aim of the present study was to develop a suitable stimulation method for direct activation of the brain in fMRI studies and to investigate the functional connectivity in the thalamo-cingulate pathway. In the first part of the study, tungsten, stainless steel, or glass-coated carbon fiber microelectrodes were implanted in the left medial thalamus (MT) of anesthetized rats, and T 2 *-weighted gradient-echo (GE) images were obtained in the sagittal plane on a 4.7 T system (Biospec BMT 47/40). Only the images obtained with the carbon fiber electrode were acceptable without a reduction of the signal-to-noise ratio (SNR) and image distortion. In the second part of the study, a series of two-slice GE images were acquired during electrical stimulation of the MT with the use of a carbon fiber electrode. A cross-correlation analysis showed that the signal intensities of activated areas in the ipsilateral Functional MRI (fMRI) is a noninvasive imaging technique for mapping brain function that utilizes neuronal activityinduced changes in blood oxygenation. These changes result in a high local concentration of deoxyhemoglobin, the paramagnetic properties of which cause blood oxygen level-dependent (BOLD) contrast (1,2). fMRI provides spatial information about multiple brain activations, and allows the functional assessment of specific sensory pathways; therefore, it is increasingly being used to elucidate the functional organization of the human brain (3). However, current fMRI methods are of limited use in exploring longrange interactions between different brain structures and specific functional activation by known neuroanatomical pathways, which require the invasive implantation of an intracranial stimulation electrode or cannula to electrically or chemically excite specific brain structures.Invasive stimulation of a deep brain region has long been used in patients to alleviate intractable pain (4,5), and a recent study using PET imaging demonstrated that the anterior cingulate cortex (ACC) is activated during thalamic deep brain stimulation in patients with chronic pain (6). However, the use of direct electrical brain stimulation in fMRI studies has potential hazards associated with the direct application of electrical current to brain tissue in the magnetic bore, and thus there is a need for a safe, efficient method for electrical brain stimulation in such studies. Several MR-compatible electrical stimulation methods for use in humans have been developed (7-10), but the strong magnetic field interference elicited by metal electrodes is still a problem in direct electrical brain stimulation in fMRI studies.fMRI studies using animal models allow invasive investigation of the neuronal mechanism underlying the brain activation shown by the BOLD signals (11). Furthermore, studies of the effect of pharmacolo...

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Safe electrical stimulation of the cochlear nerve at the promontory during functional magnetic resonance imaging

Cited by 21 publications

References 28 publications

A method for the direct electrical stimulation of the auditory system in deaf subjects: A functional magnetic resonance imaging study

A method for the direct electrical stimulation of the auditory system in deaf subjects: A functional magnetic resonance imaging study

A method for direct thalamic stimulation in fMRI studies using a glass-coated carbon fiber electrode

BOLD response to direct thalamic stimulation reveals a functional connection between the medial thalamus and the anterior cingulate cortex in the rat

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