Recording of neural signals, neural activation, and signal processing

2016 ◽  
Author(s):  
Dick F. Stegeman ◽  
Michel J. A. M. Van Putten
Keyword(s):  
Clinical Neurophysiology ◽  
Constant Current ◽  
Neural Activation ◽  
Volume Conduction ◽  
Post Processing ◽  
Neural Signals ◽  
Electrophysiological Signals ◽  
Neurophysiological Data ◽  
Constant Current Stimulation ◽  
Recent Developments

This chapter discusses recording of electrophysiological signals in the context of clinical neurophysiology. We first discuss the interpretation of signals and differences between signals in terms of their underlying (electro)physiology. As a most prominent aspect of applied electrophysiology, the biophysics of volume conduction in extracellular space is discussed. We also present some basics of advanced procedures to analyse neurophysiological data. Aspects of electrical stimulation are treated too, including recent developments in diagnostic and therapeutic constant current stimulation. We finally discuss the background of hazardous electric currents and the safety of bioelectric equipment. Aspects that are relevant in the digitization and post-processing of data are briefly reviewed.

Serotonin has different effects on two classes of Betz cells from the cat

1994 ◽  
Vol 72 (4) ◽  
pp. 1925-1937 ◽  
Author(s):  
W. J. Spain
Keyword(s):  
Firing Rate ◽  
Potassium Conductance ◽  
Membrane Conductance ◽  
Constant Current ◽  
Repetitive Firing ◽  
Calcium Dependent ◽  
Constant Current Stimulation ◽  
Ionic Mechanisms ◽  
Betz Cells

1. Intracellular recording from cat Betz cells in vitro revealed a strong correlation between the dominant effect of serotonin (5-HT) and the Betz cell subtype in which it occurred. In large Betz cells that show posthyperpolarization excitation (termed PHE cells), 5-HT evoked a long-lasting membrane depolarization, whereas 5-HT evoked an initial hyperpolarization of variable duration in smaller Betz cells that show posthyperpolorization inhibition (termed PHI cells). 2. Voltage-clamp studies revealed that 5-HT caused a depolarizing shift of activation of the cation current Ih, which resulted in the depolarization in PHE cells, whereas the hyperpolarization in PHI cells is caused by an increase in a resting potassium conductance. 3. The effect of 5-HT on firing properties during constant current stimulation also differed consistently in the two types of Betz cells. In PHE cells the initial firing rate increased after 5-HT application, but the steady firing was unaffected. The depolarizing shift of Ih activation caused the increase of initial firing rate. 4. In PHI cells 5-HT caused a decrease in spike frequency adaptation. The decrease in adaptation was caused by a combination of two conductance changes. First, 5-HT caused a slow afterdepolarization in PHI cells that could trigger repetitive firing in the absence of further stimulation. The sADP depended on calcium entry through voltage-gated channels and was associated with a decrease in membrane conductance. Second, 5-HT caused reduction of a slow calcium-dependent potassium current that normally contributes to slow adaptation. 5. In conclusion, the effect of 5-HT on excitability differs systematically in Betz cell subtypes in part because they have different dominant ionic mechanisms that are modulated. If we assume that PHE cells and PHI cells represent fast and slow pyramidal tract (PT) neurons respectively, 5-HT will cause early recruitment of fast PT cells and delay recruitment of slow PT cells during low levels of synaptic excitation.

scholarly journals Variability of neural activation during walking in humans: short heels and big calves

2011 ◽  
Vol 7 (4) ◽  
pp. 539-542 ◽  
Author(s):  
A. N. Ahn ◽  
J. K. Kang ◽  
M. A. Quitt ◽  
B. C. Davidson ◽  
C. T. Nguyen
Keyword(s):  
Neural Control ◽  
Calf Muscle ◽  
Medial Gastrocnemius ◽  
Muscle Size ◽  
Neural Activation ◽  
Neural Signals ◽  
Recruitment Pattern ◽  
Moment Arms ◽  
Different Shapes ◽  
Calf Muscles

People come in different shapes and sizes. In particular, calf muscle size in humans varies considerably. One possible cause for the different shapes of calf muscles is the inherent difference in neural signals sent to these muscles during walking. In sedentary adults, the variability in neural control of the calf muscles was examined with muscle size, walking kinematics and limb morphometrics. Half the subjects walked while activating their medial gastrocnemius (MG) muscles more strongly than their lateral gastrocnemius (LG) muscles during most walking speeds (‘MG-biased’). The other subjects walked while activating their MG and LG muscles nearly equally (‘unbiased’). Those who walked with an MG-biased recruitment pattern also had thicker MG muscles and shorter heel lengths, or MG muscle moment arms, than unbiased walkers, but were similar in height, weight, lower limb length, foot length, and exhibited similar walking kinematics. The relatively less plastic skeletal system may drive calf muscle size and motor recruitment patterns of walking in humans.

Signal-Adaptive Analog-to-Digital Converters for ULP Wearable and Implantable Medical Devices

2016 ◽  
pp. 199-228 ◽  
Author(s):  
Nabi Sertac Artan
Keyword(s):  
Low Power ◽  
Medical Devices ◽  
Sar Adc ◽  
The Other ◽  
Implantable Medical Devices ◽  
Ultra Low Power ◽  
Analog To Digital ◽  
Electrophysiological Signals ◽  
Recent Developments ◽  
Adc Architectures

The mission of this chapter is to introduce the reader the recent developments in the design of ultra-Low Power ADCs for Wearable and Implantable Medical Devices (WIMDs). The focus of this chapter will be on Signal-Adaptive Successive Approximation Register (SAR) ADC architectures and their derivatives, since the majority of the ULP medical devices rely on these architectures. The proposed chapter first provides an overview of the WIMDs, and electrophysiological signals. Then, basic SAR ADCs are introduced followed by the study of adaptive SAR ADCs. The chapter concludes with a brief summary of the other prevalent ADC architecture for WIMDs, namely the Level-Crossing ADCs.

scholarly journals Constant current stimulation may improve apraxia of eyelid opening induced by deep brain stimulation

2020 ◽  
Vol 19 ◽  
pp. 100565
Author(s):  
Katsuki Eguchi ◽  
Ichiro Yabe ◽  
Shinichi Shirai ◽  
Ikuko Iwata ◽  
Masaaki Matsushima ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Constant Current ◽  
Constant Current Stimulation ◽  
Deep Brain

scholarly journals Mixed-conducting particulate composites for soft electronics

2020 ◽  
Vol 6 (17) ◽  
pp. eaaz6767 ◽  
Author(s):  
Patricia Jastrzebska-Perfect ◽  
George D. Spyropoulos ◽  
Claudia Cea ◽  
Zifang Zhao ◽  
Onni J. Rauhala ◽  
...  
Keyword(s):  
High Performance ◽  
Particulate Composite ◽  
Particulate Composites ◽  
Spatiotemporal Resolution ◽  
Electrophysiological Signals ◽  
Neurophysiological Data ◽  
Material Solution ◽  
Soft Electronics ◽  
Single Material ◽  
Local Advanced

Bioelectronic devices should optimally merge a soft, biocompatible tissue interface with capacity for local, advanced signal processing. Here, we introduce an organic mixed-conducting particulate composite material (MCP) that can form functional electronic components by varying particle size and density. We created MCP-based high-performance anisotropic films, independently addressable transistors, resistors, and diodes that are pattern free, scalable, and biocompatible. MCP enabled facile and effective electronic bonding between soft and rigid electronics, permitting recording of neurophysiological data at the resolution of individual neurons from freely moving rodents and from the surface of the human brain through a small opening in the skull. We also noninvasively acquired high–spatiotemporal resolution electrophysiological signals by directly interfacing MCP with human skin. MCP provides a single-material solution to facilitate development of bioelectronic devices that can safely acquire, transmit, and process complex biological signals.

Signal-Adaptive Analog-to-Digital Converters for ULP Wearable and Implantable Medical Devices

2018 ◽  
pp. 413-443
Author(s):  
Nabi Sertac Artan
Keyword(s):  
Low Power ◽  
Medical Devices ◽  
Sar Adc ◽  
The Other ◽  
Implantable Medical Devices ◽  
Ultra Low Power ◽  
Analog To Digital ◽  
Electrophysiological Signals ◽  
Recent Developments ◽  
Adc Architectures

The mission of this chapter is to introduce the reader the recent developments in the design of ultra-Low Power ADCs for Wearable and Implantable Medical Devices (WIMDs). The focus of this chapter will be on Signal-Adaptive Successive Approximation Register (SAR) ADC architectures and their derivatives, since the majority of the ULP medical devices rely on these architectures. The proposed chapter first provides an overview of the WIMDs, and electrophysiological signals. Then, basic SAR ADCs are introduced followed by the study of adaptive SAR ADCs. The chapter concludes with a brief summary of the other prevalent ADC architecture for WIMDs, namely the Level-Crossing ADCs.

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