Evoked Potentials in Psychology, Sensory Physiology and Clinical Medicine


Language: Anglais
Cover of the book Evoked Potentials in Psychology, Sensory Physiology and Clinical Medicine

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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.
1. The Activities of Single Neurons and Evoked Potentials.- 1.1 General remarks: the neuron.- 1.2 General remarks: the activities of single neurons.- 1.2.1 The relation between gross slow waves recorded at the scalp and at the surface of the cortex.- 1.2.2 Gross cortical slow waves and the electrical characteristics of individual neurons.- 1.2.3 Statistical relations between gross slow waves and slow waves recorded from single cells.- 1.2.4 Summary and comments.- 2. Sensory Information Processing and Evoked Potentials.- 2.1 Introduction.- 2.1.1 Correlations between physical and mental events: theoretical models of perception.- 2.2 Evoked potentials and the physical intensity of the stimulus, evoked potentials and sensation.- 2.2.1 Introduction.- 2.2.2 Visual EPs and the physical intensity of the stimulus: visual EPs and sensation.- 2.2.3 Auditory EPs and the physical intensity of the stimulus: auditory EPs and sensation.- 2.2.4 Somatosensory EPs and the physical intensity of the stimulus: somatosensory EPs and sensation.- 2.2.5 EPs and the physical intensities of odorous and taste stimuli: EPs to odorous and taste stimuli, and sensation.- 2.3 Visual evoked potentials to spatially-unstructured stimulus fields.- 2.3.1 The effects of stimulus field size: spatially-unstructured fields.- 2.3.2 Evoked potentials and the modulation depth of stimuli: analytic and nonanalytic nonlinearities.- 2.3.3 Saturation.- 2.3.4 Evoked potential amplitude and flicker perception.- 2.4 Visual evoked potentials related to the spatial structure (patterning) of the stimulus field.- 2.4.1 Evoked potentials to flashed pattern, to pattern-appearance, to pattern-disappearance and to pattern-reversal, evoked potentials to checkerboard patterns and to bar patterns.- 2.4.2 Regular and irregular patterns.- 2.4.3 The effects of check size.- 2.4.4 The effects of stimulus field size: spatially-structured fields.- 2.4.5 Evoked potential evidence for orientation detectors.- 2.4.6 Evoked potentials to spatial patterns of chromaticity.- 2.4.7 Evoked potentials triggered by eye movements.- 2.5 Evoked potentials and binocular depth perception.- 2.6 Scalp potentials evoked by moving stimuli, lambda waves.- 2.6.1 Introduction.- 2.6.2 Evoked potentials to moving stimuli.- 2.6.3 Lambda waves.- 2.7 Rest-motion (R-M) evoked potentials.- 2.8 The effects of stimulation repetition frequency on evoked potentials.- 2.8.1 Transient stimulation and steady-state stimulation: time-domain and frequency-domain analyses.- 2.8.2 Steady-state EP components of frequency roughly 10 Hz. (‘low frequency’ region), analogue model, summation fields.- 2.8.3 Steady-state EP components in the range roughly 45 to 60 Hz (‘high frequency’ region), analogue model, summation fields.- 2.8.4 Steady-state EP components in the range roughly 12 to 25 Hz (‘medium frequency’ range).- 2.8.5 The effect of stimulus repetition frequency on EPs to pattern-reversal.- 2.8.6 The (a) subjective and (b) objective sensitivity versus frequency curves for the visual pathway.- 2.8.7 Evoked potentials, perceived frequency and perceived number.- 2.8.8 Linear and nonlinear systems analysis applied to EPs.- 2.9 Evoked potentials and colour.- 2.9.1 The effect of stimulus colour on the waveforms of transient EPs.- 2.9.2 Spectral sensitivity: Transient EPs.- 2.9.3 Spectral sensitivity: heterochromatic flicker photometry.- 2.9.4 The effects of chromatic adaptation on evoked potentials.- 2.9.5 Wavelength discrimination.- 2.9.6 Evoked potentials and colour: summary.- 2.10 Evoked potentials and the neuroanatomy of sensory pathways.- 2.10.1 Stimulation of localised retinal areas, the topographical distribution ofvisual EPs and EP-generator sites: unstructured stimulus fields.- 2.10.2 Stimulation of localised retinal areas, the topographical distribution of visual EPs and EP generator sites: spatially-structured fields.- 2.10.3 Topography of somatosensory evoked potentials, sensory pathways and EP generator sites.- 2.10.4 Topography of auditory EPs and generator sites.- 2.10.5 Evoked potentials generated in the left and right hemispheres.- 2.11 Evoked potentials and the processing of sensory information at ‘high levels’.- 2.11.1 Evoked potential correlates of perceptual suppression and of ‘fade out’ of stabilized images.- 2.11.2 Potentials evoked by visual stimuli during eye movements.- 2.11.3 Evoked potentials and interhemispheric differences, meaningful stimuli.- 2.11.4 Evoked potentials and intelligence.- 3. Evoked Potentials and Psychological Variables.- 3.1 Introduction.- 3.2 Habituation, attention, distraction and vigilance.- 3.2.1 Habituation.- 3.2.2 Attention and evoked potentials in animals: Peripheral blocking (gating) of sensory signals.- 3.2.3 Attention and EPs in man: Introduction.- 3.2.4 Attention and EPs in man.- 3.3 ‘Task relevance’, ‘meaningfulness’, ‘information delivery’, the ‘resolution of uncertainty’, ‘decision making’, etc..- 3.3.1 Introduction.- 3.3.2 Information delivery and uncertainty resolution.- 3.3.3 Task-relevance and meaningfulness.- 3.4 Electrical activity which precedes the stimulus.- 3.5 Evoked potentials and learning.- 4. Clinical Applications of Evoked Potentials.- 4.1 Introduction.- 4.2 Achievements.- (a) Sensory testing.- 4.2.1 Sensitivity to stimulus intensity, audiometry.- 4.2.2 Tests for the integrity and specialised functions of a sensory pathway.- 4.2.3 Evoked potential methods for identifying structures within the brain: stereotactic surgery.- (b) The use of evoked potentials as a supplement to other techniques in research into specific clinical conditions.- 4.2.4 Evoked potentials in psychiatry.- 4.2.5 Epilepsy and migraine.- 4.2.6 Demyelinating diseases.- 4.2.7 Maturation of the brain.- 4.3 Clinical applications of evoked potentials: possibilities.- 4.3.1 Tests for the integrity of a sensory pathway.- 4.3.2 Tests for the special functions of a sensory pathway.- 4.3.3 The location of brain lesions by EP methods.- 4.3.4 Evoked potentials and pharmacology.- 4.3.5 Evoked potentials and psychiatry.- 5. Techniques in Evoked Potential Research.- 5.1 Visual stimulators and stimulation techniques.- 5.1.1 The measurement of light and colour.- photopic photometry.- scotopic photometry.- measurement of radiant power.- measurement of colour.- terms which refer to the stimulus and the corresponding terms which refer to sensation.- conversion factors for photometric units.- 5.1.2 Maxwellian view versus ‘free view’.- 5.1.3 Exit pupils.- 5.1.4 Filters and monochromators.- 5.1.5 Stimulation by luminance changes: light sources of variable luminance.- Tungsten filament lamp.- glow modulator tube.- fluorescent tube.- Xenon flash tube.- electroluminescent panels.- projection television tube.- CRO stimulators.- modulated Xenon arc.- 5.1.6 Stimulation by luminance changes: light sources of constant luminance, and luminance modulators.- Tungsten filament lamps.- high pressure Xenon arc lamps.- electromechanical luminance modulators.- electro-optical light modulators.- 5.1.7 Useful optical components.- Dove prism.- corner cube prism.- Porro prism.- roof reflecting prism.- beamsplitter.- 5.1.8 Stimulation by spatially-structured (patterned) fields.- Flashed pattern.- pattern-appearance and pattern-disappearance.- pattern-reversal.- Tachistoscopes.- stimulators which displace the stimulus-pattern.- patterned mirror.- 5.1.9 Moving Stimuli.- 5.1.10 Evoked potentials triggered by eye movements.- 5.1.11 Stereoscopic stimuli.- 5.2 Methods for presenting odorous taste and somatosensory stimuli.- 5.2.1 Somatosensory stimulators.- 5.3 Auditory stimulators.- 5.4 Methods of recording and analysing evoked potentials.- 5.4.1 Introduction, Evoked potentials and the EEG.- 5.4.2 Electrodes and amplifiers.- 5.4.3 Noise.- 5.4.4 Multichannel recording.- 5.4.5 The ten-twenty electrode system.- 5.4.6 Spatio-temporal maps.- 5.4.7 Bipolar versus referential (i.e. ‘monopolar’) recording.- 5.4.8 Morphology of transient evoked potentials.- 5.4.9 Steady-state evoked potentials: analysis in terms of frequency.- 5.4.10 Time-domain analysis of evoked potentials.- Correlation.- summation or signal averaging.- summation devices.- boxcar integrator.- zero crossing analysis.- Dawson superposition method.- 5.4.11 Variability.- 5.4.12 Multivariate statistical analysis.- 5.4.13 Adaptive filters.- 5.4.14 Pre-filtering of EEG data.- References.- Supplementary footnotes.