A mini-cap for simultaneous EEG and fMRI recording in rodents

Sumiyoshi, Akira; Riera, Jorge J.; Ogawa, Takeshi; Kawashima, Ryuta

doi:10.1016/j.neuroimage.2010.09.056

Cited by 27 publications

(17 citation statements)

References 74 publications

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“…Details about the EEG mini-cap as well as a method to achieve low electrode impedances are provided in Riera et al (2010b). A similar EEG mini-cap was used recently by Sumiyoshi et al (2011) to perform high-resolution EEG recording inside a 7T MRI scanner. After the EEG mini-cap fixation, a silicon-based probe (NeuroNexus Technologies), which consists of a linear shank with an array of iridium oxide microelectrodes (i.e., area 177 m 2 , intervals 50 m) was perpendicularly inserted at different depths into the cerebral cortex through an available hole in the EEG mini-cap (i.e., probe area).…”

Section: Methodsmentioning

confidence: 99%

Pitfalls in the dipolar model for the neocortical EEG sources

Riera

Ogawa

Goto

et al. 2012

Journal of Neurophysiology

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111

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For about six decades, primary current sources of the electroencephalogram (EEG) have been assumed dipolar in nature. In this study, we used electrophysiological recordings from anesthetized Wistar rats undergoing repeated whisker deflections to revise the biophysical foundations of the EEG dipolar model. In a first experiment, we performed threedimensional recordings of extracellular potentials from a large portion of the barrel field to estimate intracortical multipolar moments generated either by single spiking neurons (i.e., pyramidal cells, PC; spiny stellate cells, SS) or by populations of them while experiencing synchronized postsynaptic potentials. As expected, backpropagating spikes along PC dendrites caused dipolar field components larger in the direction perpendicular to the cortical surface (49.7 Ϯ 22.0 nA·mm). In agreement with the fact that SS cells have "close-field" configurations, their dipolar moment at any direction was negligible. Surprisingly, monopolar field components were detectable both at the level of single units (i.e., Ϫ11.7 Ϯ 3.4 nA for PC) and at the mesoscopic level of mixed neuronal populations receiving extended synaptic inputs within either a cortical column (Ϫ0.44 Ϯ 0.20 A) or a 2.5-m 3 -voxel volume (Ϫ3.32 Ϯ 1.20 A). To evaluate the relationship between the macroscopically defined EEG equivalent dipole and the mesoscopic intracortical multipolar moments, we performed concurrent recordings of high-resolution skull EEG and laminar local field potentials. From this second experiment, we estimated the time-varying EEG equivalent dipole for the entire barrel field using either a multiple dipole fitting or a distributed type of EEG inverse solution. We demonstrated that mesoscopic multipolar components are altogether absorbed by any equivalent dipole in both types of inverse solutions. We conclude that the primary current sources of the EEG in the neocortex of rodents are not precisely represented by a single equivalent dipole and that the existence of monopolar components must be also considered at the mesoscopic level.electroencephalogram; neocortex; multipolar current sources; inverse problem THE DIPOLAR MODEL, used by generations of neuroscientists to represent the current sources of the electroencephalogram (EEG) in humans (Niedermeyer and Lopes da Silva 1987; Nunez and Srinivansan 2006;Plonsey 1969;Walter and Walter 1949), has roots in early interpretations by Adrian and Matthews (1934) about the origin of the Berger rhythm (i.e., the alpha rhythm). These authors suggested that the cortical electric potentials formerly observed by Berger (1929) were caused by electrical sources close to the brain surface with a polarity inversion in the axis perpendicular to it. The existence of dipole-like field distributions with axes parallel to the cortical surface was later suggested by Beevers (1944), with confirmations for the kappa rhythm (Kennedy et al. 1948) and the epileptic focal seizures (Gumnit and Takahashi 1965). This model, which eventually gained popularity in many other eme...

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Section: Methodsmentioning

confidence: 99%

Pitfalls in the dipolar model for the neocortical EEG sources

Riera

Ogawa

Goto

et al. 2012

Journal of Neurophysiology

Self Cite

111

View full text Add to dashboard Cite

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“…To solve this problem, we apply a patented EEG mini-cap 2 , which allows us to record 32-channel EEG data from rodents noninvasively. In this study, we also provide evidence about the need of an analgesic to preserve IED frequency.…”

Section: Introductionmentioning

confidence: 99%

Brain Source Imaging in Preclinical Rat Models of Focal Epilepsy using High-Resolution EEG Recordings

Bae

Deshmukh

Song

et al. 2015

JoVE

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Electroencephalogram (EEG) has been traditionally used to determine which brain regions are the most likely candidates for resection in patients with focal epilepsy. This methodology relies on the assumption that seizures originate from the same regions of the brain from which interictal epileptiform discharges (IEDs) emerge. Preclinical models are very useful to find correlates between IED locations and the actual regions underlying seizure initiation in focal epilepsy. Rats have been commonly used in preclinical studies of epilepsy 1 ; hence, there exist a large variety of models for focal epilepsy in this particular species. However, it is challenging to record multichannel EEG and to perform brain source imaging in such a small animal. To overcome this issue, we combine a patented-technology to obtain 32-channel EEG recordings from rodents 2 and an MRI probabilistic atlas for brain anatomical structures in Wistar rats to perform brain source imaging. In this video, we introduce the procedures to acquire multichannel EEG from Wistar rats with focal cortical dysplasia, and describe the steps both to define the volume conductor model from the MRI atlas and to uniquely determine the IEDs. Finally, we validate the whole methodology by obtaining brain source images of IEDs and compare them with those obtained at different time frames during the seizure onset.

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“…These results suggest that the undesirable effects of the relatively shorter off period on the subsequent block are limited. A possible explanation for the discrepancy with the literature is that the temporal stability of the fMRI signal could be compromised (i.e., the higher standard deviation in the temporal domain) in the presence of the EEG mini-cap (Sumiyoshi et al, 2011). The platinum electrodes, EEG paste, skin and wire loops may form an antenna that pick up external radio frequency energy and thus could lead to the temporal fluctuations in the observed fMRI signal.…”

Section: Discussionmentioning

confidence: 87%

“…For simultaneous EEG and fMRI recording, an EEG mini-cap compatible with the MRI environment and specially designed for rodents was prepared (Sumiyoshi et al, 2011). The EEG data were collected using a 32-channel MR-compatible BrainAmp system (Brain Products, Munich, Germany).…”

Section: Data Acquisitionmentioning

confidence: 99%

Neurovascular Uncoupling under Mild Hypoxic Hypoxia: An EEG–fMRI Study in Rats

Sumiyoshi

Suzuki

Shimokawa

et al. 2012

J Cereb Blood Flow Metab

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The effects of oxygen availability on neurovascular coupling were investigated using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), in addition to the monitoring of physiological parameters, in 16 a-chloralose-anesthetized rats. Mild hypoxic hypoxia (oxygen saturation = 83.6±12.1%) induced significant reductions in fMRI responses (P < 0.05) to electrical stimulation in the forepaw, but EEG responses remained unchanged. In addition, the changes in oxygen saturation were linearly correlated with the changes in the fMRI responses. These data further emphasize the importance of oxygen availability, which may regulate neurovascular coupling via the oxygen-dependent enzymatic synthesis of messenger molecules.

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A mini-cap for simultaneous EEG and fMRI recording in rodents

Cited by 27 publications

References 74 publications

Pitfalls in the dipolar model for the neocortical EEG sources

Pitfalls in the dipolar model for the neocortical EEG sources

Brain Source Imaging in Preclinical Rat Models of Focal Epilepsy using High-Resolution EEG Recordings

Neurovascular Uncoupling under Mild Hypoxic Hypoxia: An EEG–fMRI Study in Rats

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