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51 Normann, Richard A.Control of retinal sensitivity. I. Light and dark adaptation of vertebrate rods and conesRods and cones in Necturus respond with graded hyperpolarization to test flashes spanning about 3.5 log units of intensity. Steady background levels hyperpolarize the rods, and the rod responses become progressively smaller as background level is increased. In cones, higher background levels reduce...Retina;Light and Dark Adaptation; Recepters; Bipolars; Ganglion Cells1974
52 Horch, Kenneth W.Muscle recruitment with intrafascicular electrodesWe have studied muscle recruitment with Tefloninsulated, 25 pm diameter, Pt-Ir intrafasicular electrodes implanted in nerves innervating the gastrocnemius and soleus muscles of cats. The purpose of this study was to measure the performance of these bipolar electrodes, which had been designed to...Functional neuromuscular stimulation (FNS); Intrafascicular electrode1991
53 Christensen, Douglas A.Introduction to biomedical engineering: biomechanics and bioelectricity - part IIIntended as an introduction to the field of biomedical engineering, this book covers the topics of biomechanics (Part I) and bioelectricity (Part II). Each chapter emphasizes a fundamental principle or law, such as Darcy's Law, Poiseuille's Law, Hooke's Law, Starling's Law, levers and work in the...Bioelectricity; Kirchhoff's voltage law; Kirchhoff's current law; Coulomb's law; Thevenin equivalent circuits; Nernst potential; Matlab2009
54 Horch, Kenneth W.Identification of single units in multi-unit recordings from peripheral nervesWe are developing a computer-based method for identifying individual action potentials in multi-unit peripheral nerve recordings. Threshold level, sinusoidal stimuli are used to elicit phase-locked activity from single units. These action potentials are digitized, and a template is constructed usin...Peripheral nerve; Neural recordings; Cutaneous mechanoreceptors1988
55 Christensen, Douglas A.Interface of forest and agriculture in nonpoint pollution controlManagement practices of agriculture, including conservation and tillage options, recently have received a great deal of attention with respect to their impact upon the environment. Research efforts have focused both on the direct impacts of reduced on-site productivity resulting from the erosion of ...Suspended sediment; Channel erosion; Silviculture1983
56 Normann, Richard A.; Shoham, ShyEncoding mechanisms for sensory neurons studied with a multielectrode array in the cat dorsal root ganglionRecent advances in microelectrode array technology now permit a direct examination of the way populations of sensory neurons encode information about a limb's position in space. To address this issue, we recorded nerve impulses from about 100 single units simultaneously in the L6 and L7 dorsal root ...Sensory; Encoding; Multielectrode; Dorsal Root Ganglion; Cutaneour; Muscle2004
57 Horch, Kenneth W.Closed loop control of ankle position using muscle afferent feedback with functional neuromuscular stimulationThis paper describes a closed-loop functional neuromuscular stimulation system that uses afferent neural activity from muscle spindle fibers as feedback for controlling position of the ankle joint. Ankle extension against a load was effected by neural stimulation through a dual channel intrafasc...Neuromuscular stimulation; Functional neuromuscular stimulation (FNS); Neural electrodes1996
58 Christensen, Douglas A.Introduction to biomedical engineering: biomechanics and bioelectricity - part IIntended as an introduction to the field of biomedical engineering, this book covers the topics of biomechanics (Part I) and bioelectricity (Part II). Each chapter emphasizes a fundamental principle or law, such as Darcy's Law, Poiseuille's Law, Hooke's Law, Starling's law, levers and work in the a...Biological membranes; Poiseuille's law; Hooke's law; Starling's law of the heart; Matlab2009
59 Christensen, Douglas A.; Andrade, Joseph D.Improved sensitivity in ellipsometry of thin biochemical films by employing sublayersEllipsometry is widely used for investigating the optical properties of thin films on planar substrates, including films of adsorbed proteins or polymers. The average thickness and effective refractive index of the adsorbed layer are calculated by measuring the A and ¥ ellipsometry parameters. Unfo...Biochemical films; SiO2 sublayer1990
60 Normann, Richard A.; Kolb, Helga; Lasater, Eric M.Signal integration at the pedicle of turtle cone photoreceptors: an anatomical and electrophysiological studyThe morphology of the axon which connects the cell body and pedicle of turtle cone photoreceptors was studied by light and electron microscopy. The axon which contains numerous synaptic vesicles, some endoplasmic reticulum, and a few cisternae is basically filled with cytoplasm. The length of the ax...Cone Photoreceptor, Voltage Clamp; Isolated Cells; Input Resistance; Cell Body-Pedicle Coupling1989
61 Horch, Kenneth W.Separation of action potentials in multiunit intrafascicular recordingsClassification of action potentials in multiunit recordings was based on the use of various types of features to uniquely characterize action potentials from different cells. We compared classification results obtained using three types of descriptive features: digitized data points, amplitude and ...Long-term implantable intrafascicular electrodes; Nerve recordings; Simulated neural data1992
62 Christensen, Douglas A.; Horch, Kenneth W.Accelerated dual-degree BS/MS program - experience with the first three yearsWe have initiated a pilot program that accelerates the studies of a small group of highly qualified students early in their college careers and allows them to earn both a bachelor's degree and a master's degree in about four years after starting college. It does this by introducing them early to res...Accelerated dual-degree program2004
63 Normann, Richard A.; Maynard, Edwin M.Neuronal interactions improve cortical population coding of movement directionInteractions among groups of neurons in primary motor cortex (MI) may convey information about motor behavior. We investigated the information carried by interactions in MI of macaque monkeys using a novel multielectrode array to record simultaneously from 12-16 neurons during an arm-reaching task. ...Motor Cortex; Monkey; Population Coding; Movement1999
64 Normann, Richard A.Effects of background illumination on the photoresponses of red and green cones1. The photoresponses of light- and dark-adapted red and green cone photoreceptors were recorded intracellularly in the retina of the turtle, Pseduemys scripta elegans. Background illumination produced similar effects on both types of cones. 2. In response to the onset of a prolonged, steady backgro...Turtles; Adaptation, Ocular; Retina; Signal Transmission1979
65 Horch, Kenneth W.; Tuckett, Robert P.; Burgess, Paul RichardNeural signal for skin indentation depth. II. Steady indentationsThe glabrous skin of the monkey's hand was stimulated with a waveform that indented the skin at a rate of 0.4 mm/set, held the skin steadily or nearly steadily indented for 12 set or longer, and then retracted back to the starting position. Recordings were made of activity in single afferent fibe...Skin; Indentation; Nerve impulses1983
66 Normann, Richard A.; Horch, Kenneth W.; Cha, KichulMobility performance with a pixelized vision systemA visual prosthesis, based on electrical stimulation of the visual cortex, has been suggested as a means for partially restoring functional vision in the blind. The prosthesis would create a pixelized visual sense consisting of punctate spots of light (phosphenes). The present study investigated the...Visual Prosthesis; Mobility; Phosphene Simulator1992
67 Horch, Kenneth W.Information contrained in sensory nerve recordings made with intrafascicular electrodesMultiunit recordings were made in anesthetized cats with chronically implanted intrafascicular electrodes over a period of six months. Neural signals recorded with these electrodes consisted of activity in sensory fibers innervating a variety of cutaneous mechanoreceptors. Mechanical stimuli wer...Intrafascicular electrodes; Functional electrical stimulation (FES); Closed-loop control1991
68 Gesteland, Raymond F.Translation of Rl7 RNA fragmentsExamination of the events during infection of cells by RNA phages reveals phemonomena that are surprisingly complex for a virus that has only enough information to code for three to four proteins. The coat protein is synthesized at a rapid rate through most of the infectious cycle making it the pre...Electrophoresis; RNA, Messenger; Peptide Biosynthesis; Kinetics1969
69 Normann, Richard A.; Maynard, Edwin M.Neural interface for a cortical vision prosthesisThe development of a cortically based vision prosthesis has been hampered by a lack of basic experiments on phosphene psychophysics. This basic research has been hampered by the lack of a means to safely stimulate large numbers of cortical neurons. Recently, a number of laboratories have developed a...Neuroprosthetics; Artificial Vision; Electrode Arrays; Multielectrode Recordings; Biocompatibility1999
70 Normann, Richard A.; Kolb, HelgaNeural organization of the retina of the turtle Mauremys caspica: a light microscope and Golgi studyThe organization of the retina of the turtle species Mauremys caspica, found in fresh water ponds of Israel, has been examined by light microscopical techniques including examination of fresh wholemount retina, one micron blue-stained vertical sections and Golgi-stained material. The anatomical find...Turtle Retina; Photoreceptors; Golgi Technique; Amarcine Cells1988
71 Christensen, Douglas A.Using the cardiovascular system to illustrate fundamental laws and principles in a freshman courseOur Fundamentals of Bioengineering I course is organized around key physical and engineering laws and principles. A semester-long Major Project is assigned which integrates many of these principles by modeling the human systemic cardiovascular system, using both Matlab computer analysis and assembly...Matlab2002
72 Horch, Kenneth W.Are the extrinsic muscles better suited for signaling joint angles or finger tip location?We used a biomechanical model of the human long finger to determine whether the extrinsic muscles are better suited for estimating the finger's joint angles or for estimating location of the finger tip. We found that two of the extrinsic muscles together could provide information sufficient to direc...Extrinsic muscles; Metacarpophalangeal joint; Biomechanical models1997
73 Horch, Kenneth W.; Normann, Richard A.Simulation of a phosphene field based visual prosthesisA visual prosthesis for the blind based upon electrical stimulation of the visual cortex requires the development of an array of electrodes. To establish design specifications for such an electrode array, we have conducted psychophysical experiments with normally sighted subjects wearing a portable...Visual prosthesis; Phosphene simulator1990
74 Normann, Richard A.; Branner, AlmutLong-term stimulation and recording with a penetrating microelectrode array in cat sciatic nerveWe studied the consequences of long-term implantation of a penetrating microelectrode array in peripheral nerve over the time course of 4-6 mo. Electrode arrays without lead wires were implanted to test the ability of different containment systems to protect the array and nerve during contractions o...Cats; Microelectrodes; Prosthesis Implantation; Sciatic Nerve2004
75 Horch, Kenneth W.Stability of chronic intrafascicular electrode recordingsWe have implanted intrafascicular electrodes in peripheral nerves of cats and have recorded neural activity from a small population of nerve fibers for as long as six months, suggesting that these electrodes can be used on a chronic basis to acquire information about limb position, muscle force and ...Intrafascicular electrodes; Electrode recordings1989
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