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ECoG-Based BCIs
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
After the implantation of the electrodes, bioamplifiers with high temporal resolution (i.e., an adequate sampling rate) and with sufficient range and resolution in voltage (i.e., an adequate quantization level) are required to capture all important features of ECoG signals. In practice, a sampling rate of 1 kHz or higher, a voltage range of at least several dozens of μV, and a digital resolution of 24 bits are recommended. These are good recording practices, as the spectral bandwidth of ECoG signals extends to ~250 Hz, and voltage amplitudes attenuate inversely with increasing frequency (i.e., from several hundred microvolts at low frequencies to several hundred nanovolts at higher frequencies). Ideally, the bioamplifier should minimize the amount of analog filtering: high-pass filters can remove evoked potentials of interest, whereas low-pass filters with too low of a cutoff frequency will remove important high-frequency content of ECoG signals. The physiological basis of these signals and the most relevant features for BCI applications are discussed in Section 16.3.
Giga-Ohm High-Impedance FET Input Amplifiers for Dry Electrode Biosensor Circuits and Systems
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Gaetano Gargiulo, Paolo Bifulco, Rafael A. Calvo, Maria Romano, Mariano Ruffo, Richard Shephard, Mario Cesarelli, Craig Jin, Alistair McEwan, André van Schaik
Figure 8.4 presents a schematic diagram of the bioamplifier as it was proposed in [12]. The bio-amplifier design is based on the classical three op-amp instrumentation amplifier with the gain value set by a single resistor (whose value is 220 Ω in Figure 8.4). As one should note from the figure, in parallel with the gain resistor there is an optical controlled voltage generator (transistors 4N35). This voltage source may have the same effect as a capacitive cell (high-pass effect) placed at the gain resistor place, when its voltage is controlled by a block having the same transfer function. In the proposed circuit, the controller has been realized with an integrator, thus realizing the feedback block with a transfer function of 1/s.
Cystic Fibrosis Transmembrane Conductance Regulator Attenuates Oxidative Stress-Induced Injury in Diabetic Retinopathy Rats
Published in Current Eye Research, 2023
Hui Wang, Xian Su, Qian-Qian Zhang, Ying-Ying Zhang, Zhan-Ya Chu, Zhao-Hui Sun, Jin-Ling Zhang, Yu-Fen Tang
Two months after the induction of diabetes, the rats were dark-adapted for 12 h. Rats were then anesthetized with pentobarbital sodium (3%, 0.6 mL/kg intraperitoneally) and xylazine hydrochloride injection (0.19 mL/kg intramuscularly). The pupils of all rats were dilated with compound tropicamide eye drops. The corneal electroretinogram (ERG) electrode was attached to the center of a custom-made plastic light diffuser placed over the cornea. The reference electrode was placed under the skin on the right cheek, 1 cm from the eye. Recordings were performed by using Power Lab system 2/25 (AD Instruments, New South Wales, Australia). Responses were differentially amplified at the gain of 1000 times using an AC (alternate current)-coupled bioamplifier ML132 (AD Instruments) and filtered through a bandpass filter ranging from 0.3 to 500 Hz to yield b waves. The amplitude and implicit time of the b waves were measured.
Exposure to antenatal corticosteroids and reduced respiratory sinus arrhythmia in adult survivors of extremely low birth weight
Published in International Journal of Neuroscience, 2019
Calan Savoy, Karen J. Mathewson, Louis A. Schmidt, Katherine M. Morrison, Saroj Saigal, Michael H. Boyle, Ryan J. Van Lieshout
At the 22–26 year visit, ECG was recorded continuously for 2 min via two disposable ECG electrodes placed on the medial forearms, from participants resting without distraction or stimulus in a seated position. At the 30–35 year visit, the duration of recording was extended to 6 min and electrodes were placed below the right clavicle and upon the lower left rib in a modified Lead II configuration. As the recordings were taken at rest and in the absence of a stressor or stimulus, respiratory rate was not monitored in this study, in agreement with previous research [37]. ECG signals were recorded at each assessment, amplified by an individual SA Instrumentation Bioamplifier (SA Instrumentation CO, San Diego, CA), filtered between 0.1 Hz (high pass) and 1000 Hz (low pass), and digitized at a sampling rate of 512 Hz. The acquisition software at ages 22–26 was Snapshot-Snapstream (HEM Data Corp., Southfield, MI), and at ages 30–35, SnapMaster (HEM Data Corp., Southfield, MI).
Pudendal nerve injury impairs anorectal function and health related quality of life measures ≥2 years after 3D conformal radiotherapy for prostate cancer
Published in Acta Oncologica, 2018
Eng (Eric) Yeoh, Rochelle Botten, Addolorata Di Matteo, Marcus Tippett, Jonathon Hutton, Robert Fraser, Phillip G. Dinning, David Wattchow
PNTML assessment was performed by an accredited technical officer employing a disposable glove-mounted St Mark’s electrode and transrectal nerve stimulation technique (13L40 St Mark’s Pudendal ElectrodeTM, Medtronic Functional Diagnostics A/S, Skovlunde, Denmark). Square wave stimuli of 0.05 ms duration and 10 mA were delivered at one-second intervals. The electromyography (EMG) recordings were acquired via a MacLab or PowerLab 8S or 4S system with a MacLab or PowerLab bioamplifier using ScopeTM (V3.4.3-4.1) software (ADInstruments Pty. Ltd, Castle Hill, NSW, Australia). Multiple recordings were taken on each side and the most well defined action potentials selected for the determination of the latency. The mean latency from these multiple curves was determined. Latency was defined as the time between the stimulation of the pudendal nerve at the level of the ischial spine (the electrical pulse being recorded as a stimulus artifact) and commencement of depolarization of the anal sphincter [15]. A lack of pudendal nerve response was defined as no sphincter contraction on EMG recording in response to stimulus [11].