David Regan

Bio: David Regan is an academic researcher from York University. The author has contributed to research in topics: Contrast (vision) & Visual acuity. The author has an hindex of 67, co-authored 251 publications receiving 15059 citations. Previous affiliations of David Regan include University of Toronto & Toronto Western Hospital.

Human Brain Electrophysiology: Evoked Potentials and Evoked Magnetic Fields in Science and Medicine

Abstract: Consid6rant que l'excessive hypersp6cialisation des neurosciences est un obstacle ~ la diffusion et /t l'enseignement d 'un savoir scientifique pourtant commun ~ plusieurs champs de recherches au sein des sciences du cerveau, l 'auteur se propose d'&udier les potentiels 6voqu6s (PE) de mani~re r6solument multidisciplinaire, depuis l'6tude du fonctionnement de groupes neuronaux chez les primates jusqu'aux activit6s perceptives, cognitives et aux comportements moteurs 61abor6s chez l 'homme. Destin6 autant aux &udiants de doctorat qu'aux chercheurs exp6riment6s plus sp6cialis6s, cet ouvrage apporte aux premiers une introduction concr6te h la probl6matique g6n6rale des PE au moyen d'exemples simples, et aux seconds une revue exhaustive et concise de la place des PE en l'6tat actuel de la science sur des aspects fondamentaux ou des applications cliniques. L'auteur adopte syst6matiquement une d6marche fructueuse de confrontation entre m6thodologie et clinique. Pour tenir compte des horizons divers des lecteurs, l 'auteur n ' a pas craint de d6velopper des notions << 616mentaires >> de traitement du signal destin6es aux biologistes et aux m6decins et des notions solides de neurophysiologie g6n6rale destin6es aux math6maticiens et aux ing6nieurs. L'ouvrage, tr~s volumineux, est divis6 en 3 parties: la premi6re (165 pages, 11 chapitres et 3 appendices) est une revue exhaustive des diff6rents moyens de traitement du signal applicables aux PE. La d6marche de l 'auteur reste pragmatique: il importe d'avoir toujours h l'esprit les contraintes impos6es par le choix de tel ou tel module math6matique ou statistique sur l'interpr6tation des r6sultats et surtout sur la gen6se d'art6facts. La tongueur de cette premiere pattie, qui correspond ~t un gros volume ordinaire rassemble et commente l'ensemble des techniques utilis6es dans l'6tude des PE des plus anciennes aux plus actuelles, en insisrant sur les caract6ristiques propres aux stimuli et leurs cons6quences dans l'interpr&ation d 'un plan exp6rimental. Les pi6ges sp6cifiques tt l'enregistrement et l'interpr6tation des PE sont analys6s avec rigueur et humour. La 2 e pattie aborde les aspects fondamentaux (320 pages, 8 chapitres) : int6r& et place des PE dans l'6tude des processus cognitifs, des comportements moteurs, des voies auditives, somesth6siques, visuelles, vestibulaires, olfactives, gustatives et douloureuses. La r6daction de chaque chapitre fait appel aux notions les plus actuelles de neuro-anatomie, de neurophysiologie exp6rimentale et de psychophysiologie. Le 8 e chapitre de cette seconde pattie est une mise au point sur l'int6r~t de l'6tude des champs magn&iques dans les PE. Enfin, la 3 e partie (80 pages, 5 chapitres) est une revue de la litt6rature concise et exhaustive concernant les applications cliniques des PE auditifs, visuels et somesth6siques. Le dernier chapitre est consacr6 aux troubles psychiatriques de l'adulte et de l 'enfant. L'ouvrage cite plus de 3000 r6f6rences dont plus de 150 correspondent aux contributions personnelles de l'auteur. Le style est alerte, l'auteur reste toujours tr6s proche des pr6occupations concr6tes des lecteurs. Un index fourni permet de se rapporter facilement ~ un d6tail particulier. L'6dition est remarquable, soign6e et tr6s lisible. Ce livre est une somme monumentale ~ placer dans toutes les biblioth6ques de neurophysiologie.

Evoked Potentials in Psychology, Sensory Physiology and Clinical Medicine

Abstract: Only quite recently has it become technically possible to record, from elec trodes attached to the scalp, the human brain's electrical responses to sensory stimulation The core of this book is a critical survey of endeavours to use these electrical responses (called evoked potentials) as tools in attempts to discover the ways in which the brain first processes incoming sensory information and then forms internal representations of features ofthe external world Buttressed by quantities of undeniably sloppy evoked potential research there are some who would dismiss out of hand the recording of evoked potentials as being comparable to 'holding an oscilloscope probe 6 feet in diameter up to a computer and pronouncing from the resultant waveform on the underlying structure and function'; many would contrast the scientific value of recording the activities of single nerve cells with microelectrodes However, although it is certainly true that the brain may indeed function in a way which would not be susceptible to the approaches of the evoked potential researcher it might equally well resist the stratagems of the single-cell man If, for example, the neural correlate of some sensation were the state of some large population of nerve cells, then the present-day researcher who records in great detail the activity of one single cell or of a very few cells would be faced with a major problem in trying to see the forest for the trees"

Postadaptation orientation discrimination.

Abstract: An orientational difference of only 0.3–0.5 deg can be discriminated between two gratings or two lines, although psychophysical channels and cortical cells both have comparatively broad orientation bandwidths of 10–25 deg. One proposed explanation for the fineness of orientation discrimination is that, while detection is determined by the most excited orientation-tuned neural elements, superthreshold orientation discrimination is determined by difference signals between these elements [ Westheimer, J. Opt. Soc. Am.66, 332 ( 1976)]. This implies that, if stimulus orientation is changed slightly, the most important elements for discriminating this change will be those whose relative activity changes most, even though the excitation of these elements may be comparatively weak. In accord with this prediction, we found that adapting to a high-contrast grating degraded discrimination for test gratings inclined at about 10–20 deg to the adapting grating while having little effect on the detection of these inclined gratings. For test gratings parallel to the adapting grating, discrimination was improved, but detection was degraded. Either an opponent-process or a line-element model can account for these effects of adaptation. An opponent model can also explain our findings that subjects do not confound orientation change with contrast change and that suprathreshold orientation discrimination is almost independent of contrast, varying by only ±10% from about 3 to about 25 times contrast threshold. A discrimination model must incorporate reliable storage of spatial frequency, because discrimination was not affected by increasing the interval between grating presentations from 1 to 10 sec. In spatial form vision the relation between postadaptation detection and discrimination is formally similar along the dimensions of orientation and of size, and these two independent spatial discriminations can be modeled in formally similar ways, for example, in terms of orientation opponency and size opponency among multiple local elements, each of which is tuned to a different orientation and/or size.

An Introduction to the Event-Related Potential Technique

Abstract: The event-related potential (ERP) technique in cognitive neuroscience allows scientists to observe human brain activity that reflects specific cognitive processes. In An Introduction to the Event-Related Potential Technique, Steve Luck offers the first comprehensive guide to the practicalities of conducting ERP experiments in cognitive neuroscience and related fields, including affective neuroscience and experimental psychopathology. The book can serve as a guide for the classroom or the laboratory and as a reference for researchers who do not conduct ERP studies themselves but need to understand and evaluate ERP experiments in the literature. It summarizes the accumulated body of ERP theory and practice, providing detailed, practical advice about how to design, conduct, and interpret ERP experiments, and presents the theoretical background needed to understand why an experiment is carried out in a particular way. Luck focuses on the most fundamental techniques, describing them as they are used in many of the world's leading ERP laboratories. These techniques reflect a long history of electrophysiological recordings and provide an excellent foundation for more advanced approaches. The book also provides advice on the key topic of how to design ERP experiments so that they will be useful in answering questions of broad scientific interest. This reflects the increasing proportion of ERP research that focuses on these broader questions rather than the "ERPology" of early studies, which concentrated primarily on ERP components and methods. Topics covered include the neural origins of ERPs, signal averaging, artifact rejection and correction, filtering, measurement and analysis, localization, and the practicalities of setting up the lab.

A sensorimotor account of vision and visual consciousness-Authors' Response-Acting out our sensory experience

Abstract: Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Several lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual \"filling in,\" visual stability despite eye movements, change blindness, sensory substitution, and color perception.

A sensorimotor account of vision and visual consciousness

Abstract: Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Several lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual “filling in,” visual stability despite eye movements, change blindness, sensory substitution, and color perception.

The Perception of the Visual World. By James J. Gibson. U.S.A.: Houghton Mifflin Company, 1950 (George Allen & Unwin, Ltd., London). Price 35s.

Abstract: Let's read! We will often find out this sentence everywhere. When still being a kid, mom used to order us to always read, so did the teacher. Some books are fully read in a week and we need the obligation to support reading. What about now? Do you still love reading? Is reading only for you who have obligation? Absolutely not! We here offer you a new book enPDFd the perception of the visual world to read.