• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.831-841
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• 2001

Objective : Somatosensory evoked potentials(SSEPs) have been used widely both experimentally and clinically to monitor the function of central nervous system and peripheral nervous system. Studies of SSEPs have reported the various recording techniques and patterns of SSEP. The previous SSEP studies used scalp recording electrodes, showed mean vector potentials which included relatively constant brainstem potentials(far-field potentials) and unstable thalamocortical pathway potentials(near-field potentials). Even in invasive SSEP recording methods, thalamocortical potentials were variable according to the kinds, depths, and distance of two electrodes. So they were regarded improper method for monitoring of upper level of brainstem. The present study was conducted to investigate the characteristics of somatosensory evoked field potentials(SSEFPs) of the cerebral cortex that evoked by hindlimb stimulation using ball electrode and the pathways of SSEFP by recording the potentials simultaneously in the cortex, VPL nucleus of thalamus, and nucleus gracilis. Methods : In the first experiment, a specially designed recording electrode was inserted into the cerebral cortex perpendicular to the cortical surface in order to recording the constant cortical field potentials and SSEFPs mapped from different areas of somatosensory cortex were analyzed. In the second experiment, SSEPs were recorded in the ipsilateral nucleus gracilis, the contralateral ventroposterolateral thalamic nucleus(VPL), and the cerebral cortex along the conduction pathway of somatosensory information. Results : In the first experiment, we could constantly obtain the SSEFPs in cerebral cortex following the transcutaneous electrical stimulation of the hind limb, and it revealed that the first large positive and following negative waves were largest at the 2mm posterior and 2mm lateral to the bregma in the contralateral somatosensory cortex. The second experiment showed that the SSEPs were conducted by way of posterior column somatosensory pathway and thalamocortical pathway and that specific patterns of the SSEPs were recorded from the nucleus gracilis, VPL, and cerebral cortex. Conclusion : The specially designed recording electrode was found to be very useful in recording the localized SSEFPs and the transcutaneous electrical stimulation using ball electrode was effective in evoking SSEPs. The characteristic shapes, latencies, and conduction velocities of each potentials are expected to be used the fundamental data for the future study of brain functions, including the hydrocephalus model, middle cerebral artery ischemia model, and so forth.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1998-2003
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• 2007

A flexible but implantable polyimide-based neural implant was fabricated for reliable and stable long-term monitoring of neural activities from brain. The developed neural implant provides 3-dimensional (3D) $3{\times}3$ structure, avoids any hand handling, and makes the insertion more efficient and reliable. Any film curvature caused by residual stress was not observed in the electrode. The 3D flexible polyimide electrode penetrated a dense gel whose stiffness is close to live brain tissue, because a ${\sim}1{\mu}m$ thick nickel was electroplated along the edge of the shank in order to improve the stiffness. The recording sites were positioned at both side of the shank to increase the probability of recording neural signals from a target volume of tissue. Impedance remained stable over 72 hours because of extremely low moisture uptake in the polyimide dielectric layers. At electrical recording test in vitro, the fabricated electrode showed excellent recording performance, suggesting that this electrode has the potential for great recording from neuron firing and long-term implant performance.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.151-155
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• 1993

Evoked potentials(EP) measured with scalp electrodes are often described as a deterministic process corrupted by uncorrelated electrical activities occuring in the brain and These electrical activities(ongoing EEG) refer to noise in EP recording. The Conventional method to determine the EP waveform requires long recording time. Unfortunately most of algorithm developed are too complicated for implementation in real time. Thus, conner EP recording devices use Ensemble average for real time processing. In this paper introduce EP recording hardware for processing advanced algorithm in real tlne. This hardware is composed of DSP chip(TMS320c25) and microcomputer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.582-587
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• 2002

Current information storage devices, such as HDD, CD/DVD-ROM/RW, probe-based memory and hologram memory, are compared with biological information storage mechanisms in DNA and brain memory. Newly developed approaches to overcome the limit of storage capacity are introduced in both magnetic and optical recording devices. Linear and areal density of information stored in the biological and mechanical storages are compared for the applications and developments of new storage devices.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.27 no.4
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• pp.43-49
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• 2009

• Korean Journal of Clinical Laboratory Science
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• v.51 no.4
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• pp.468-474
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• 2019

Deep brain stimulation (DBS) is an effective surgical procedure for treating drug refractory movement disorders, and DBS involves delivering high frequency electrical stimulation to deep brain nuclei. Microelectrode recording (MER) is a complementary test that can precisely identify the location of deep brain nuclei, along with MRI correlation, during DBS surgery to improve the surgical outcome and minimize side effects. The purpose of this paper is to analyze the neuro-physiological waveforms and identify the usefulness of MER by analyzing the MER performed during DBS surgery for treating movement disorders. We retrospectively reviewed 28 patients who underwent MER during DBS surgery for movement disorders from January to December 2018. Of the 28 patients, 38 MERs for the subthalamic nucleus (STN), 10 MERs for the globuspallidusinternus (Gpi), and 4 MERs for the ventral intermediate thalamic nucleus (VIM) were performed. In all the cases, the target sites were found and micro-stimulations were used to check for side effects and to readjust the target sites. The clinical symptoms of all 28 patients improved after surgery. In conclusion, MER is a useful test that employs neuro-physiological waveforms to accurately identify the deep brain nuclei, along with MRI correlation, to improve the DBS surgical outcomes for movement disorders and to minimize side effects.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.38-40
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• 2005

Microdrive with high precision and light mass enough to install on mouse head was fabricated for recording the reliable signal of neuron cell to understand the brain study. The proposed microdrive has three H-form PZT actuators and its guide structure. The microdrive operation principle is based on the well known inchworm principle. The synchronization of three PZT actuators is able to produce the linear motion along the guide structure. Our proposed microdrive has a precise accuracy of about 100nm and a long stroke of about 5mm. The electrode which is used for the recording of the action potential of the neuron cell was fixed at one of PZT actuators. The proposed microdrive was suited to acquisition of signals from in vivo extra-cellular single-unit recoding. On the condition of the anesthetized mouse, the single-unit signals could be recorded by using the proposed microdrive. In addition, applying the PZT microdrive to an alert mouse, we try to implant it on a mouse brain skull to explore single neuron firing.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.129-140
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• 2017

In this paper, a $4{\times}32$-channel neural recording system capable of acquiring neural signals is introduced. Four 32-channel neural recording ICs, complex programmable logic devices (CPLDs), a micro controller unit (MCU) with USB interface, and a PC are used. Each neural recording IC, implemented in $0.18{\mu}m$ CMOS technology, includes 32 channels of analog front-ends (AFEs), a 32-to-1 analog multiplexer, and an analog-to-digital converter (ADC). The mid-band gain of the AFE is adjustable in four steps, and have a tunable bandwidth. The AFE has a mid-band gain of 54.5 dB to 65.7 dB and a bandwidth of 35.3 Hz to 5.8 kHz. The high-pass cutoff frequency of the AFE varies from 18.6 Hz to 154.7 Hz. The input-referred noise (IRN) of the AFE is $10.2{\mu}V_{rms}$. A high-resolution, low-power ADC with a high conversion speed achieves a signal-to-noise and distortion ratio (SNDR) of 50.63 dB and a spurious-free dynamic range (SFDR) of 63.88 dB, at a sampling-rate of 2.5 MS/s. The effectiveness of our neural recording system is validated in in-vivo recording of the primary somatosensory cortex of a rat.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.529-530
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• 2009

• Molecules and Cells
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• v.40 no.8
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• pp.523-532
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• 2017

Functional near-infrared spectroscopy (fNIRS) is a noninvasive optical imaging technique that indirectly assesses neuronal activity by measuring changes in oxygenated and deoxygenated hemoglobin in tissues using near-infrared light. fNIRS has been used not only to investigate cortical activity in healthy human subjects and animals but also to reveal abnormalities in brain function in patients suffering from neurological and psychiatric disorders and in animals that exhibit disease conditions. Because of its safety, quietness, resistance to motion artifacts, and portability, fNIRS has become a tool to complement conventional imaging techniques in measuring hemodynamic responses while a subject performs diverse cognitive and behavioral tasks in test settings that are more ecologically relevant and involve social interaction. In this review, we introduce the basic principles of fNIRS and discuss the application of this technique in human and animal studies.