Neff Contributions to Sensory Physiology

Volume 5
1. Auflage 2013
ISBN: 978-1-4831-9158-4
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 238 Seiten

Contributions to Sensory Physiology: Volume 5 presents a theory about the physiological basis of sensation. It discusses some research made in microscopic anatomy and psychophysics. It addresses the functional significance and physiological mechanisms of the sensory systems. Some of the topics covered in the book are the simple cells of the striate cortex; the concept of a receptive field; definition of a unimodal simple cell; inhibitory components in the receptive field; stimulus contrast and mean level of luminance; specificity of inhibitory zones; and experimental procedures for recording average response histogram. The relation and possible importance of taste bud cells are covered. The comparison of foliate, vallate, and fungiform buds are discussed. The text describes the nature of taste receptor sites. A study of the location of receptor sites on taste cells is presented. A chapter is devoted to the mechanochemical model of taste excitation. Another section focuses on the proposals for molecular specificity. The book can provide useful information to scientists, doctors, students, and researchers.

Autoren/Hrsg.

Neff, William D.

Inhaltsverzeichnis

1;Front Cover;1
2;Contributions to Sensory Physiology;4
3;Copyright Page;5
4;Table of Contents;6
5;List of Contributors;8
6;Preface;10
7;Contents of Previous Volumes;12
8;Chapter 1. Simple Cells of the Striate Cortex;16
8.1;I. THE CONCEPT OF A RECEPTIVE FIELD;16
8.2;II. RECEPTIVE FIELDS OF NEURONS IN THE STRIATE CORTEX;17
8.3;III. EXCITATORY COMPONENTS IN THE RECEPTIVE FIELD;24
8.4;IV. INHIBITORY COMPONENTS IN THE RECEPTIVE FIELD;42
8.5;V. BINOCULAR SPECIFICITIES: BINOCULAR GATE NEURON;55
8.6;VI. FORM DISCRIMINATION: SOME SPECULATIONS;58
8.7;ACKNOWLEDGMENT;59
8.8;REFERENCES;59
9;Chapter 2. Relations and Possible Significance of Taste Bud Cells;62
9.1;I. INTRODUCTION;62
9.2;II. EXPERIMENT NO. 1: IXth NERVE SECTION;63
9.3;III. EXPERIMENT NO. 2: THYMIDINE LABELING;86
9.4;IV. EXPERIMENT NO. 3: HORIZONTAL SERIAL SECTIONS;89
9.5;V. GENERAL DISCUSSION;101
9.6;VI. CONCLUSIONS;108
9.7;ACKNOWLEDGMENTS;108
9.8;REFERENCES;108
10;Chapter 3. The Nature of Taste Receptor Sites;112
10.1;I. NATURE OF THE PROBLEM;112
10.2;II. LOCATION OF RECEPTOR SITES ON TASTE CELLS;113
10.3;III. HETEROGENEITY OF RECEPTOR SITES;114
10.4;IV. QUANTITATIVE MEASURES OF STIMULUS–RECEPTOR SITE INTERACTION;123
10.5;V. RECEPTOR SITE PLASTICITY;129
10.6;VI. A MECHANOCHEMICAL MODEL OF TASTE EXCITATION;130
10.7;VII. CONCLUSION;140
10.8;REFERENCES;141
11;Chapter 4. Auditory Receptor Organs of Reptiles, Birds, and Mammals;144
11.1;I. INTRODUCTION;144
11.2;II. REPTILES;146
11.3;III. BIRDS;156
11.4;IV. MAMMALS;170
11.5;V. SUMMARY;188
11.6;ACKNOWLEDGMENTS;189
11.7;REFERENCES;189
12;Chapter 5. Old and New Data on Tone Perception;194
12.1;I. INTRODUCTION;194
12.2;II. FREQUENCY ANALYSIS BY THE EAR;195
12.3;III. TIMBRE AND THE HARMONICS;199
12.4;IV. EFFECT OF PHASE ON TIMBRE;204
12.5;V. COMBINATION TONES;209
12.6;VI. BEATS OF SIMPLE TONES;213
12.7;VII. TONAL CONSONANCE AND DISSONANCE;219
12.8;VIII. DISCUSSION;225
12.9;REFERENCES;229
13;Author Index;232
14;Subject Index;236

Leseproben

Simple Cells of the Striate Cortex

G.H. Henry and P.O. Bishop,     Department of physiology, John Curtin School of Medical Research, Australian National University, Canberra, Australia

Publisher Summary

This chapter provides an overview of the simple cells of the striate cortex. Cortical neurons have a hierarchical order where successive transformations of receptive field properties take place from simple up to higher-order hypercomplex cells. The properties of the more complex cells are derived from the convergence of afferents cells with simpler properties. The simple cells in Layer IV of the striate cortex are predominately of the stellate type. The neural pathways from the eyes are largely independent until they reach the level of the cortex and come together for the first time on the cells in the striate cortex. Because a majority of neurons in the striate cortex may be discharged from either eye, the possibility exists of producing a discharge via one eye and the testing for inhibition via the other. In the striate cortex of the cat or monkey, a number of classes of neurons exist—such as, simple, complex, hypercomplex, and, nonoriented.

I The Concept of a Receptive Field

II Receptive Fields of Neurons in the Striate Cortex

A Types of Simple Cell: Responses to Moving Stimuli

B Experimental Procedures for Recording Average Response Histograms

C Definition of a Unimodal Simple Cell

III Excitatory Components in the Receptive Field

A Discharge Peaks in the Average Response Histogram

B Discharge Centers in the Receptive Field

C Influence of One Contrast Border on Another

D Orientation Specificity and Direction Selectivity

E Discharge Center and Direction Selectivity

F Stimulus Contrast and Mean Level of Luminance

G Stimulus Velocity

IV Inhibitory Components in the Receptive Field

A Experimental Procedures for Recording Inhibition

B Inhibitory Zones in the Receptive Field

C Spatial Organization of Discharge Center and Inhibitory Side Bands

D Common Type of Simple Cell Binocular Interaction Field

E Activity Profile of Receptive Field Plots

F Specificity of Inhibitory Zones

V Binocular Specificities: Binocular Gate Neuron

VI Form Discrimination: Some Speculations

References

I The Concept of a Receptive field

The idea of a receptive field has been applied to both the somesthetic and visual systems. The most general definition of a receptive field is thatspatial area or region within which a stimulus of sufficient intensity and proper quality will influence the firing of a sensory neuron. Since the concept refers to a single cell or axon, its development clearly had to wait upon the introduction of the technique of single-unit recording.

The idea of a receptive field as a basis for the organization of a sensory system is due to Adrian (1928) as a result of his studies of single fibers from skin receptors. It was not until 1940, however, that Hartline provided the firstdefinition of a receptive field of a visual neuron based on single-unit recording. He isolated single nerve fiber activity from small bundles dissected free from the anterior surface of the frog retina (Hartline, 1940). In general, however, single-unit recording by microdissection is not applicable to the central nervous system, including the retina, and once again progress had to wait upon technical development—this time, the use of microelectrodes for single-cell recording. The nature of the organization of the receptive field of retinal ganglion cells was further developed by Barlow (1953) in the frogand Kuffler (1953) in the cat, both of whom used microelectrodes for isolating single cell activity. The systematic study of the receptive fields of neurons in the visual cortex began with Hubel and Wiesel (1959,1962).

Because of the technique of shiningspots of light directly onto the exposed retina, the original definition of the receptive field of a visual neuron referred to the area of the retina over which adequate stimulation influenced the impulse activity of that neuron. Even with the introduction of the unopened eye preparation (Kuffler, 1953), the stimulating spot of light was still observed directly on the retinal surface. A major advance took place with the movement away from a narrow preoccupation with the retinal image and the development of the concept of areceptive field in terms of object space either by presenting, as stimuli, actual objects in the visual field or patterns of light on a screen. This technical innovation clearly allowed a much greater flexibility in respect to the range of stimuli that could be presented and brought with it a change in outlook toward the use of more natural stimuli under conditions that might be encountered inthe normal visual environment (Lettvin , 1959). The receptive field is now defined in terms of an area or region in the visual field.

II Receptive Fields of Neurons in the Striate Cortex

Based on the organization of their receptive fields, Hubel and Wiesel (1962, 1968) have defined a number of classes of neurons in the striate cortex of the cat and monkey, namely, simple, complex, hypercomplex, and nonoriented. They have also developed the idea of a hierarchical order of cortical neurons whereby successive transformations of receptive field properties take place from simple up to higher-order hypercomplex cells, and they have suggested ways in which the properties of the more complex cells may be derived from the convergence of afferents from cells with simpler properties. Hubel and Wiesel found that the majority of cells in the visual cortex respond best to the movement of straight-line stimuli—narrow elongated rectangles of light (slits), straight-line borders between areasof different brightness (edges), and dark bars against a light background. A slight change in the orientation of the line separatingthe light from the dark area was usually enough to reduce greatly the effectiveness of the stimulus. The receptive fields were classified as simple when they had spatially distinct “on” and “off” areas separated by parallel straight lines, the separate areas being mapped experimentally by stationary spots or slits of light flashed on and off. Hubel and Wiesel (1968) reported that “the commonest simple fields were those with long narrow ‘on’-centres sandwiched between two more extensive ‘off’ regions, and those with an ‘on’ and an ‘off’ region lying side by side.” They explicitly equated the “on” regions with excitation and the “off”regions with inhibition and, on this basis, have frequently described the receptive fields of simple cells as being subdivided into distinct excitatory and inhibitory regions (Hubel and Wiesel, 1962). They reported summation within the separate excitatory and inhibitory parts and antagonism between the two regions. Furthermore, they claimed that, knowing the exact configuration of the receptive field of a simple cell in terms of “on” and “off” areas, it was possible to predict, in a qualitative way, the response to any shape of stimulus, stationary or moving.

There are two lines of support for the idea that the simple cell is the first member of the cortical hierarchy to receive information from the lateral geniculate nucleus. In the first place, the response characteristics of these cells are relatively simple, being more complex than those of geniculate neurons but less so than those of complexcells and cells further up the proposed cortical hierarchy. Indeed, the scheme that Hubel and Wiesel (1962) put forward for explaining the organization of simple receptive fields involved the pooling of outputs of a large number of geniculate neurons. By contrast, the properties of complex fields were not easily accounted for by supposing that these cells receive afferents directly from the lateral geniculate nucleus. A possible scheme for explaining the organization of complex cells was provided by supposing that they haveas their afferents axons from cells with simple fields. The other line of support is anatomical. The cells with simple fields were the predominant cell type recorded in Layer IV, the layer of termination of the cortical afferents from the lateral geniculate nucleus (Hubel and Wiesel, 1962,...