electroencephalographic (eeg) signal recording system and procedure

Stimulating Mouse Brain with a Low-Cost EEG and Millimeter-Sized Coil

Transcranial magnetic stimulation (TMS) is a promising tool for human brain science, clinical application, and animal model research because of its non-/low invasiveness. During the early stage of TMS applications, measurement of the cortical effect in response to single- and paired-pulse TMS in humans and animals was restricted to the motor cortex; easily measurable output was limited to motor evoked potentials and induced myoelectric potentials involving the motor cortex1,2. To expand the brain regions that can be measured by TMS modulation, electroencephalographic (EEG) recording was integrated with single- and paired-pulse TMS as a useful method to directly examine the excitability, connectivity, and spatiotemporal dynamics of areas throughout the whole brain3,4,5. Thus, the simultaneous application of TMS and EEG recording (TMS-EEG) to the brain has been used to probe various superficial cortical brain areas of humans and animals to investigate intracortical neural circuits (see Tremblay et al.6). Moreover, TMS-EEG systems can be used to examine additional cortical spatiotemporal characteristics, including the propagation of signals to other cortical areas and the generation of oscillatory activity7,8.
However, the mechanism of action of TMS in the brain remains speculative because of the non-invasiveness of TMS, which limits our knowledge of how the brain functions during TMS applications. Therefore, invasive translational studies in animals ranging from rodents to humans are of crucial importance to understand the mechanism of the effects of TMS on neural circuits and their activity. In particular, for combined TMS-EEG experiments in animals, a simultaneous stimulation and measurement system has not been intensively developed for small animals. Therefore, experimentalists are required to construct such a system by trial and error according to their specific experimental requirements. In addition, mouse models are useful among other in vivo animal species models because many transgenic and strain-isolated mice strains are available as biological resources. Thus, a convenient method to build a TMS-EEG-combined measurement system for mice would be desirable for many neuroscience researchers.
This study proposes a TMS-EEG-combined method that can be applied for simultaneous stimulation and recording of the mouse brain, which is the main type of transgenic animal used in research, and that can easily be constructed in typical neuroscience laboratories. First, a low-cost EEG recording system is described using conventional screw electrodes and a flexible substrate to reproducibly assign an electrode-array position in each experiment. Second, a magnetic stimulation system is constructed using a millimeter-sized coil, which can easily be custom-made in typical laboratories. Third, the TMS-EEG-combined system records neural activity in response to sound and magnetic stimulation. The method presented in this study can reveal the mechanisms that generate specific disorders in small animals, and the results obtained in the animal models can be translated to understand the corresponding human disorders.

Author Spotlight: Low-Cost Electroencephalographic Recording System Combined with a Millimeter-Sized Coil to Transcranially Stimulate the Mouse Brain In Vivo  

Low-Cost Electroencephalographic Recording System Combined with a Millimeter-Sized Coil to Transcranially Stimulate the Mouse Brain In Vivo

In neuroscience, TMS and EEG recording are frequently used to advance our understanding of the brain. TMS is especially promising due to its non-invasiveness. Combining TMS with EEG recording enables researchers to explore excitability, connectivity, and spatiotemporal dynamics across various brain regions.This protocol aims to develop a simultaneous stimulation measurement system for TMS-EEG experiments with small animals. These system have not been extensively developed, forcing researchers to create a system to trial and error according to the unique experimental requirements. This easily adaptable approach can be set up in standard neuroscience labs, making it more accessible and practical for researchers.The findings of this study will advance research and elucidating mechanisms behind specific disorders in small animals, which are essential models for human candidates. Further, these models will improve their understanding of human conditions and help guide the creation of more effective treatments and interventions.

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Electroencephalographic (EEG) Signal Recording System and Procedure  

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Video: Electroencephalographic (EEG) Signal Recording System and Procedure  

A low-cost electroencephalographic (EEG) recording system is proposed here to drive transcranial magnetic stimulation (TMS) of the mouse brain in vivo, utilizing a millimeter-sized coil. Using conventional screw electrodes combined with a custom-made, flexible, multielectrode array substrate, multi-site recording can be carried out from the mouse brain. In addition, we explain how a millimeter-sized coil is produced using low-cost equipment usually found in laboratories. Practical procedures for fabricating the flexible multielectrode array substrate and the surgical implantation technique for screw electrodes are also presented, which are necessary to produce low-noise EEG signals. Although the methodology is useful for recording from the brain of any small animal, the present report focuses on electrode implementation in an anesthetized mouse skull. Furthermore, this method can be easily extended to an awake small animal that is connected with tethered cables via a common adapter and fixed with a TMS device to the head during recording.The present version of the EEG-TMS system, which can include a maximum of 32 EEG channels (a device with 16 channels is presented as an example with fewer channels) and one TMS channel device, is described. Additionally, typical results obtained by the application of the EEG-TMS system to anesthetized mice are briefly reported.

A low-cost electroencephalographic recording system combined with a millimeter-sized coil is proposed to drive transcranial magnetic stimulation of the mouse brain in vivo. Using conventional screw electrodes with a custom-made, flexible, multielectrode array substrate, multi-site recording can be carried out from the mouse brain in response to transcranial magnetic stimulation.

A low-cost electroencephalographic (EEG) recording system is proposed here to drive transcranial magnetic stimulation (TMS) of the mouse brain in vivo, ...

Electroencephalographic (EEG) Electrode Implantation on Mouse Brain

To begin, use an intraperitoneal anesthetized mouse and expose the skull Using standard surgical procedures. Attach the stainless steel rod mounted to the 2D electrode array on the backside of the flexible substrate to a manipulator. Then place the flexible substrate on the exposed skull.Adjust the location of channels 3 and 14 on the array to fit within the inferior colliculus. Draw four small circles at the locations of channels 3, 8, 9, and 14 on the skull with a permanent marker to serve as targeting landmarks. Next, dry the skull surface to improve the adherence of the dental cement and to electrically isolate the 2D electrode array on the flexible substrate from the mouse skull.Apply a layer of dental cement to the skull surface approximately one millimeter thick and allow the cement to cure for approximately 30 minutes. Align the flexible substrate in line with the small circular marks on the surface of the skull. Then position the tip of a dental drill on each electrode pad hole on the flexible substrate and carefully drill into the skull.Using a screwdriver, secure the miniature screw electrodes into the drill holes of the skull. Crimp the head of the screw electrode and the electrode pad firmly. Finally, measure the conductance between each screw electrode and the connector with testing equipment, such as an LCR meter to confirm electrical conductivity.