By V. Yussuf. Antioch University Yellow Springs OH.
Assess for ocular effects of systemic drugs and systemic effects of ophthalmic drugs cheap 100 mg penegra prostate 07. Critical Thinking Scenario Jean Green 50mg penegra overnight delivery prostate cancer dogs, a 40-year-old accountant, has made an appointment to have her eyes examined because she has been having difﬁculty reading small print. When she arrives at the ofﬁce, you explain that the examination will include using medications to dilate her eyes and a test for glaucoma. Which drugs are used to dilate the eyes for examination, and how they work. When the conjunctiva is irritated or certain emotions are experienced (eg, sadness), the The eye is the major sensory organ through which the per- lacrimal gland produces more ﬂuid than the drainage son receives information about the external environment. The excess ﬂuid overﬂows Extensive discussion of vision and ocular anatomy is beyond the eyelids and becomes tears. The sclera is a white, opaque, fibrous tis- • The eyelids and lacrimal system function to protect the sue that covers the posterior five sixths of the eyeball. The eyelid is a covering that acts as a barrier to the The cornea is a transparent, special connective tissue entry of foreign bodies, strong light, dust, and other po- that covers the anterior sixth of the eyeball. The canthi (singular, canthus) are blood vessels and connective tissue, continues forward the angles where the upper and lower eyelids meet. The iris is composed of pigmented The lacrimal system produces a ﬂuid that constantly cells, the opening called the pupil, and muscles that moistens and cleanses the anterior surface of the eye- control the size of the pupil by contracting or dilating ball. The ﬂuid drains through two small openings in the in response to stimuli. The retina is the innermost inner canthus and ﬂows through the nasolacrimal duct layer of the eyeball. The most common type of glaucoma is called primary Light rays do not travel directly to the retina. Its etiology is unknown, but contribut- they are deﬂected in various directions according to the ing factors may include advanced age, a family history of density of the ocular structures through which they pass. In addition, the inci- is the area of the retina where ophthalmic blood vessels dence of glaucoma in African Americans is about three times and the optic nerve enter the eyeball. Closed-angle glau- • The structure and function of the eyeball are further in- coma is usually an acute situation requiring emergency ﬂuenced by the lens, aqueous humor, and vitreous body. It may occur when pupils are dilated and the outﬂow The lens is an elastic, transparent structure; its function of aqueous humor is blocked. Darkness and drugs with anti- is to focus light rays to form images on the retina. It is cholinergic effects (eg, atropine, antihistamines, tricyclic anti- located behind the iris and held in place by suspensory depressants) may dilate the pupil, reduce outﬂow of aqueous ligaments attached to the ciliary body. Most of the ﬂuid ﬂows through the pupil into the anterior chamber (between the cornea and the lens Inﬂammatory or Infectious Conditions and anterior to the iris). Infections may result from production and drainage of aqueous humor are approx- foreign bodies, contaminated hands, contaminated eye med- imately equal, and normal intraocular pressure (<21 mm ications, or infections in contiguous structures (eg, nose, face, Hg) is maintained. Common inflammatory and infectious disorders causes increased intraocular pressure. The vitreous body include the following: is a transparent, jelly-like mass located in the posterior • Conjunctivitis is a common eye disorder that may be portion of the eyeball. It functions to refract light rays caused by allergens (eg, airborne pollens), bacterial or and maintain the normal shape of the eyeball. Symp- toms include redness, tearing, itching, edema, and burn- ing or gritty sensations. Bacterial conjunctivitis is often DISORDERS OF THE EYE caused by Staphylococcus aureus, Streptococcus pneu- moniae, or Haemophilus inﬂuenzae and produces mu- The eye is subject to the development of many disorders that copurulent drainage. Conjunctivitis with a purulent threaten its structure, function, or both. Some disorders in discharge is most often caused by the gonococcus; which ophthalmic drugs play a prominent role are discussed corneal ulcers and scarring may result. A hordeolum (commonly called Refractive Errors a stye) is often associated with blepharitis. Refractive errors include myopia (nearsightedness), hyper- • Keratitis (inﬂammation of the cornea) may be caused opia (farsightedness), presbyopia, and astigmatism. Ophthalmic drugs are used major symptom is pain, which ranges from mild to se- only in the diagnosis of the conditions; treatment involves vere. Pseudomonal ulcers are less common but may rapidly progress to perforation.
Fetal toxicity and neonatal death have occurred are informed of potential hazards discount penegra 100mg fast delivery prostate cancer 710. Dosage requirements may be less pre- while taking one of these drugs generic 50mg penegra with visa prostate diet, the drug should be stopped and dictable during pregnancy, and serum drug levels and other as- the patient informed of possible adverse drug effects on the fetus. Digoxin also has Nonsteroidal Anti-Inﬂammatory Drugs (NSAIDs) been administered to the mother for treatment of fetal tachycardia Use of NSAIDs (eg, ibuprofen) should generally be avoided, espe- and heart failure. All of the drugs are FDA category Diuretics D in the third trimester or near delivery. If these drugs are taken in Thiazides (eg, hydrochlorothiazide) cross the placenta. They are the third trimester, effects on human fetuses include constriction of not associated with teratogenesis, but they may cause other ad- the ductus arteriosis prenatally, nonclosure of the ductus arteriosius verse effects. Because the drugs decrease plasma volume, de- postnatally, impaired function of the tricuspid valve in the heart, creased blood ﬂow to the uterus and placenta may occur with pulmonary hypertension, degenerative changes in the myocardium, resultant impairment of fetal nutrition and growth. Other adverse impaired platelet function with resultant bleeding, intracranial effects may include fetal or neonatal jaundice, thrombocytopenia, bleeding, renal impairment or failure, oligohydramnios, gastro- hyperbilirubinemia, hemolytic jaundice, ﬂuid and electrolyte im- intestinal (GI) bleeding or perforation, and increased risk of necrotizing enterocolitis, a life-threatening disorder. These drugs are delivery, maternal effects include delayed onset of labor and deliv- not indicated for treatment of dependent edema caused by uterine ery and increased risk of excessive bleeding. They also are inhibitors (eg, celecoxib) have not been studied in pregnant women; not effective in prevention or treatment of pregnancy-induced diclofenac is contraindicated in pregnant women. Thyroid Hormone Loop diuretics (eg, furosemide) are not considered teratogenic, Levothyroxine does not readily cross the placenta and it seems but animal studies indicated fetal toxicity and death. However, it may cause tachycardia in azides, loop diuretics may decrease plasma volume and blood ﬂow the fetus. When given as replacement therapy in hypothyroid to the placenta and fetus. Marijuana impairs formation of DNA and RNA, the Thus far, the main emphasis on drug use during pregnancy basic genetic material of body cells. It also may decrease the has related to actual or potential adverse effects on the fetus. Heroin ingestion in- Despite the general principle that drug use should be avoided creases the risks of pregnancy-induced hypertension, third when possible, pregnant women may require drug therapy trimester bleeding, complications of labor and delivery, and for various illnesses, increased nutritional needs, pregnancy- postpartum morbidity. FETAL THERAPEUTICS Although the major concern about drugs ingested during Herbal and Dietary Supplements pregnancy is adverse effects on the fetus, a few drugs are given to the mother for their therapeutic effects on the fetus. Pregnancy increases nutritional needs and vitamin and min- These include digoxin for fetal tachycardia or heart failure, eral supplements are commonly used. Folic acid supplemen- levothyroxine for hypothyroidism, penicillin for exposure to tation is especially important, to prevent neural tube birth maternal syphilis, and prenatal corticosteroids to promote defects (eg, spina biﬁda). Such defects occur early in preg- surfactant production to improve lung function and decrease nancy, often before the woman realizes she is pregnant. In addition, pregnancy increases folic Antacids may be used if necessary. Because little systemic acid requirements by 5- to 10-fold and deficiencies are com- absorption occurs, the drugs are unlikely to harm the fetus if mon. A supplement is usually needed to supply adequate used in recommended doses. For deficiency states, 1 mg or more daily may be cralfate may also be used. Herbal supplements are not recommended during preg- Gestational Diabetes nancy. Ginger has been used to relieve nausea and vomit- ing during pregnancy, with a few studies supporting its use. Overall, it has not been proven effective, but is probably This is called gestational diabetes. Most women without risk factors, or Pregnancy-Associated Symptoms whose initial test was normal, should be tested between 24 and and Their Management 28 weeks of gestation. For women with gestational diabetes, initial management Anemias includes nutrition and exercise interventions, calorie restric- tion for obese women, and daily self-monitoring of blood glu- Three types of anemia are common during pregnancy. If these interventions are ineffective, recombinant physiologic anemia, which results from expanded blood vol- human insulin is needed to keep blood sugar levels as nearly ume. A second is iron-deﬁciency anemia, which is often re- normal as possible. Oral antidiabetic drugs are generally con- lated to long-term nutritional deﬁciencies.
This book was set in Times New Roman on 3B2 by Asco Typesetters order 100mg penegra mens health 50 plus, Hong Kong order penegra 50mg online mens health zac efron photoshop, and was printed and bound in the United States of America. Library of Congress Cataloging-in-Publication Data Toward replacement parts for the brain : implantable biomimetic electronics as neural prostheses / edited by Theodore W. Loeb 2 Microelectronic Array for Stimulation of Large Retinal Tissue Areas 15 Dean Scribner, M. Taylor 3 Imaging Two-Dimensional Neural Activity Patterns in the Cat Visual Cortex using a Multielectrode Array 43 David J. Normann, and Alexei Koulakov II NEURAL REPRESENTATIONS 4 Brain Parts on Multiple Scales: Examples from the Auditory System 69 Ellen Covey 5 A Protocol for Reading the Mind 91 Howard Eichenbaum 6 Cognitive Processes in Replacement Brain Parts: A Code for All Reasons 111 Robert Hampson, John Simeral, and Sam A. Deadwyler 7 Mathematical Modeling as a Basic Tool for Neuromimetic Circuits 129 Gilbert A. Berger vi Contents 8 Real-Time Spatiotemporal Databases to Support Human Motor Skills 159 Shahram Ghandeharizadeh III NEURON/SILICON INTERFACES 9 Long-Term Functional Contact between Nerve Cell Networks and Microelectrode Arrays 177 Guenter W. Keefer, Alexandra Gramowski, and Simone Stuewe 10 Building Minimalistic Hybrid Neuroelectric Devices 205 James J. Hickman 11 The Biotic/Abiotic Interface: Achievements and Foreseeable Challenges 221 Roberta Diaz Brinton, Walid Sousou, Michel Baudry, Mark Thompson, and Theodore W. Berger IV HARDWARE IMPLEMENTATIONS 12 Brain-Implantable Biomimetic Electronics as a Neural Prosthesis for Hippocampal Memory Function 241 Theodore W. Keith Jenkins 15 Reconﬁgurable Processors for Neural Prostheses 335 Jose Mumbru, Krishna V. The meeting was sponsored by the National Institute of Mental Health (NIMH), the University of Southern California (USC) Alfred E. Mann Institute for Biomedical Engineering, and the USC Center for Neural Engineering. The motivation for the meeting was a growing realization among neuroscientists, engineers, and medical researchers that our society was on the threshold of a new era in the ﬁeld of neural prosthetics; namely, that in the near future it would be possible to mathematically model the functional properties of dif- ferent regions or subregions of the brain, design and fabricate microchips incorporat- ing those models, and create neuron/silicon interfaces to integrate microchips and brain functions. In this manner, our rapidly increasing understanding of the com- putational and cognitive properties of the brain could work synergistically with the continuing scientiﬁc and technological revolutions in biomedical, computer, and elec- trical engineering to realize a new generation of implantable devices that could bi- directionally communicate with the brain to restore sensory, motor, or cognitive functions lost through damage or disease. Recognizing the ambitious nature of such a vision, the goal of the meeting and thus of this book, was to explore various dimensions of the problem of using biomi- metic devices as neural prostheses to replace the loss of central brain regions. The ﬁrst two chapters focus on advances in developing sensory system prostheses. The re- markable success in development and clinical application of the cochlear implant, and the rapid progress being made in developing retinal and visual prostheses, pro- vide the best foundation for considering the extension of neural prostheses to central brain regions. Beyond the issues of designing multisite electrode arrays for the complex geometry and cytoar- chitecture of cortical brain (chapters 3 and 12) it is clear that neural representations of sensory receptive ﬁelds are not static, but in fact are dynamic, changing over time viii Preface and with experience (chapter 4). The limitations of using static, multisite electrode arrays to extract information from a dynamically changing population of neurons must be taken into account when designing neural prosthetic systems triggered by sensory ensemble codes. Sophisticated analyses of multielectrode recordings from the hippocampus in behaving animals (chapters 5 and 6) emphasize the complexity of neural representations typical of memory systems in the brain. Hippocampal neu- rons respond to multiple dimensions (modalities) of a given learning and memory task, with key, higher-level features distributed across populations of spatially dispa- rate cells. How to extract information from systems with such complex functional properties in real time, process that information, and then transmit the processed output back to other parts of the brain to inﬂuence cognitive function and behavior constitutes a considerable challenge. Given the multiple levels of function that characterize the nervous system (i. Chapter 8 o¤ers some practical approaches for how to organize multidimensional time series data to achieve representational schemes for sensorimotor coupling. Despite these complexities, considerable progress is being made in implementing biologically realistic neural system models in hardware. The importance of this step is that, to design and construct a neural prosthetic system that can interact with the brain, the mathematical models required to capture the nonlinear dynamics and non- stationarity of neural functions need to be miniaturized for implantation in the brain or on the skull, and need to take advantage of the parallel processing and high-speed computation o¤ered by microelectronic and optoelectronic technologies. Examples of such ﬁrst steps in very large-scale integration (VLSI) are described here for the hippocampus (chapter 12) and thalamocortical systems (chapter 13). In addition, the use of photonics and holographic technologies for achieving high-density con- nectivity between neural processors (chapter 14) and multiple-pattern storage for context-dependent connectivities and functions (chapter 15) o¤er novel and exciting possibilities for achieving the complexity of neural system functions in hardware. Chapter 16 o¤ers a series of intriguing insights on the potential synergy between neu- roscience and computer engineering; that is, how the capabilities of current VLSI and photonic technologies can facilitate the implementation of biologically based models of neural systems, and how our increasing understanding of neural organization and function can inspire next-generation computational engines. Finally, designing and controlling the interface between neurons and silicon is a critical consideration in the development of central brain neural prostheses.
They are sensitive mechanorecep- modulating fusimotor drive can effectively alter the tors penegra 50 mg visa prostate otc, responsive to the static and dynamic compo- Ia support to movements (see Chapter 3) penegra 50 mg with amex androgen hormone 2 ep1. Thenon-linearchar- Post-activation depression at the Ia acteristics of the primary ending enable it to signal afferent-motoneurone synapse the very initiation of a length change. Ia afferents are the largest and most rapidly conducting periph- Areduction in post-activation depression may be an eral nerve ﬁbres, with conduction velocities up to important spinal mechanism underlying spasticity. Group Ia affer- vation of a synapse is a general phenomenon in the ents bifurcate on entering the spinal cord through nervous system, but again monosynaptic Ia connec- the dorsal root and run in both the rostral and tionsonmotoneuronesprovidethemostconvenient caudal directions in the dorsal columns (Fig. The rostro- Background from animal caudal spread of individual collaterals within the experiments ventral horn is limited, and it is unlikely that more than a single collateral of a Ia ﬁbre has access to a Initial ﬁndings given motoneurone. All dendritic regions accessible to investigation as well as the soma receive monosy- Since the clinical description of the tendon jerk at naptic connections (see Henneman & Mendell, theendofthenineteenthcentury,ittookalongtime: 1981). Quadriceps A further factor inﬂuencing the size of Ia EPSPs is the type of motoneurone EPSPsarelargestinsmallmotoneuronesinnervating MN Dorsal slow-twitch motor units (Eccles, Eccles & Lundberg, column 1957), and monosynaptic Ia EPSPs evoked on max- imal stimulation of the homonymous nerve scale quite precisely with motor unit type. There is thus GM Soleus a direct correlation with the fatigue resistance and an inverse correlation with the tetanic force pro- Ia afferent duced by the motor unit and with the size of the motoneurone(seeR. MN The mechanism underlying this particular distri- bution has been extensively debated. Apart from the fact that small motoneurones have a higher input resistance, it has been assumed that invasion Fig. Ia of Ia terminals is a graded process that is gener- afferents (dashed lines) originating from muscle spindle ally more complete in the terminal arborisations primary endings of the soleus have monosynaptic projections on small motoneurones because they have fewer to homonymous soleus motoneurones (MNs), and to branch points (see Henneman & Mendell, 1981). Distribution of heteronymous monosynaptic Ia excitation Hindlimb Strength of monosynaptic Ia projections to individual motoneurones Whereasearlystudiesemphasisedthehomonymous nature of monosynaptic Ia excitation, the technique Homonymous and heteronymous motoneurones of facilitating the monosynaptic reﬂex allowed Lloyd Monosynaptic Ia excitation is generally stronger in (1946)toreveal effects from synergistic (heterony- homonymous than heteronymous motoneurones mous) muscles acting at the same joint. This is because each Ia ﬁbre the same function are welded into a functional sends terminals to all or nearly all of its homony- unit by monosynaptic Ia excitation with recipro- mous motoneurones but only to some synergistic cal Ia inhibition of antagonists. However, heteronymous Ia EPSPs withintracellularrecordingtechniquesrevealedthat may be larger than the homonymous ones in some the Ia synergism is by no means restricted to the 66 Monosynaptic Ia excitation mechanical agonists operating at the same joint, of force production. Recently, it has been shown but may include distant muscles operating at differ- that, in the high decerebrate cat, muscle reﬂexes due ent joints, e. These heteronymous Ia connec- ofIaandIbafferentsisunknown:theinhibitoryeffect tions were believed to have evolved to assist feline of Ib afferents may be reversed to facilitation during locomotion (R. Methodology Cat forelimb Underlying principles The above data promoted the view that the Ia syner- Stimulation of Ia afferents elicits in motoneurones gism is rather rigid and that, by not allowing much an excitation that can be assessed in human sub- ﬂexibility, it is optimised for assisting the ﬂexion– jects using the H reﬂex, the PSTHs of single motor extensionmovementsoflocomotion(cf. Several properties may be used to conﬁrm movement repertoire than the hindlimb and a more that a response results from monosynaptic Ia exci- extensive distribution of Ia connections, with many tation: (i) a central delay consistent with monosy- transjoint connections from proximal to distal mus- naptic transmission; (ii) a low electrical threshold of cles. It has been argued that this system should be the responsible afferents; (iii) a similar effect pro- capableofcopingwithandassistingthelargerreper- duced by a tendon tap, and (iv) the ﬁrst response to toire of manipulatory paw movements (Fritz et al. This indicates that muscle spin- Soleus H reﬂex dle afferents contribute signiﬁcantly to muscle acti- vation during locomotion (however, see Chapter 3, As discussed in Chapter 1, percutaneous electri- p. When allowance canbecontaminatedbyoligosynapticpathways(see was made for the conduction in proximal portions Chapter 1,pp. Similarly, when the H reﬂex of roots and within cord itself, the time left was too is of reasonable size, only with the ﬁrst recruited short for interneuronal transmission. This indicates motoneurones will the monosynaptic Ia EPSP not thattheﬁrstmotoneuronesdischarginginthesoleus be contaminated by oligosynaptic inputs (Burke, Hreﬂex do so at a latency consistent with a monosy- Gandevia & McKeon, 1984). In support of this view, the variabil- ity in latency of a single motor unit in the H reﬂex Ia origin of the afferent limb of the is low, consistent with the existence of only a sin- homonymous monosynaptic pathway gle central synapse (Trontelj, 1973). The conclusion of the soleus that the latency of the soleus H reﬂex is determined by monosynaptic transmission has been conﬁrmed Apart from the monosynaptic transmission, several by Ertekin, Mungan & Uludag (1996), again using other arguments support the view that Ia ﬁbres form intrathecal recordings of the dorsal and ventral root the afferent limb of the monosynaptic pathway. Effect of tendon taps Abroader peak of facilitation is produced in the Monosynaptic Ia excitation of soleus PSTHs of soleus motoneurones by percussion on motoneurones may also be demonstrated the Achilles tendon (Birnbaum & Ashby, 1982; using the PSTH method Burke, Gandevia & McKeon, 1983), a potent stimu- Stimulation of Ia afferents in the posterior tibial lus for muscle spindle primary endings (Lundberg & nerve consistently evokes a peak of homonymous Winsbury, 1960). The onset of the peak of excitation monosynapticexcitationinsoleusmotorunitsatthe insinglesoleusmotorunitsoccursabout5–6mslater same latency as the H reﬂex (Ashby & Labelle, 1977; with tendon percussion than with electrical stimula- Mao et al. The equivalence of the latencies tion, a difference consistent with the time required with the two methods is illustrated in Fig. The H reﬂex at rest (b) and theposteriortibial-induceddischargeofasingleunit Low electrical threshold duringvoluntarycontraction(c)occuratvirtuallythe same latency, and this is the latency of the ﬁrst bin InagreementwiththeﬁndingthatIaafferentsarethe of the peak of excitation in PSTHs from the unit ((d), largest afferent ﬁbres in the cat, the afferent volley of (e)). This therefore reﬂects monosynaptic excitation the soleus H reﬂex is produced by the afferents of the (cf.
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