Salamanders are subject to misconceptions even among vertebrate zoologists and physiologists. They are often said to exist only in northern temperate zones, being bound to aquatic or very moist cool habitats. In reality, more than half of all salamander species live in subtropical and tropical zones, ex clusively in the New World. Again, more than half of the salamand~r species have become totally independent of aquatic habitats following the loss of a free larval stage. Many of the subtropical and tropical salamanders have become adapted to rather high temperatures up to 26-28 DC. The brain and the sensory systems of salamanders are often considered to be primitive, and their behavior is thought to be simple and uninfluenced by learning. However, careful studies show that the salamander brain possesses virtually all the ana tomical and functional properties found in anurans, which are usually regarded as being much more evolved with respect to the guidance of comparable behavior. Most of the salamander species not only possess a highly efficient visual system, which is the topic of the present work, but can orient themselves almost as effectively by means of olfaction, vibration sense, and electroreception. Furthermore, it has recently been shown that at least part of their behavior, especially that concerned with feeding and prey preferences, is strongly influenced by individual experience.
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ISBN-13
978-3-540-17870-5 (9783540178705)
DOI
10.1007/978-3-642-72713-9
Schweitzer Klassifikation
1 Taxonomy, Geography and Ecology of Salamanders.- 2 Visually Guided Behavior.- 2.1 Feeding Behavior.- 2.1.1 Functional Morphology of Feeding in Salamanders.- 2.1.2 Prey Preferences and Natural Diets of Salamanders.- 2.1.3 Experimental Analysis of Visually Guided Prey-Capture Behavior.- 2.1.4 Interaction Between Visual and Olfactory Guidance of Feeding Behavior.- 2.1.5 Ontogeny of Feeding Behavior and the Role of Learning.- 2.2 Optomotor Behavior.- 2.3 Visual Mate Recognition in Newts.- 3 Morphology and Function of the Salamander Eye.- 3.1 General Morphology.- 3.2 Morphology of the Retina.- 3.2.1 Light Microscope Overview of the Structure..- 3.2.2 Classification of Retina Ganglion Cells..- 3.2.3 Neuronal Connections in the Retina.- 3.2.4 Size, Number, and Density of Photo- receptors and Retina Ganglion Cells.- 3.3 Functional Aspects.- 3.3.1 Dioptrics of the Salamander Eye.- 3.3.2 Accommodation.- 3.3.3 Visual Acuity.- 3.4 Eye Degeneration in Troglobitic Salamanders.- 4 Anatomy of the Visual System.- 4.1 General Anatomy of the Salamander Brain.- 4.1.1 Forebrain.- 4.1.2 Diencephalon.- 4.1.3 Praetectum.- 4.1.4 Midbrain.- 4.1.5 Cerebellum.- 4.1.6 Medulla Oblongata and Cervical Spinal Cord.- 4.2 Visual and Visuomotor Projections and Pathways.- 4.2.1 Visual Afferents to the Brain.- 4.2.2 Comparison with Anuran Retinofugal Projections.- 4.2.3 Topic Organization of Retinal Projections to the Diencephalon and the Tectum.- 4.2.4 Development of Retinofugal Projections.- 4.3 Intrinsic Organization and Cytoarchitecture of the Optic Tectum and the Diencephalon.- 4.3.1 Tectum Opticum.- 4.3.2 Diencephalon.- 4.4 Central Visual and Visuomotor Pathways.- 4.4.1 Tectal Afferents and Efferents.- 4.4.2 Afferent and Efferent Pathways of the Praetectum.- 4.4.3 Afferents and Efferents of the Thalamus.- 4.4.4 Summary and Comparison of Tectal and Diencephalic Afferents and Efferents.- 5 Neurophysiology of Visually Guided Behavior.- 5.1 Electrophysiological Methods.- 5.2 Response Properties of Retina Ganglion Cells to Preylike Stimuli.- 5.3 Color Coding in Retina Ganglion Cells.- 5.4 Response Characteristics of Tectal Neurons..- 5.4.1 Salamandra salamandra.- 5.4.2 Hydromantes italicus.- 5.5 Recordings from Diencephalic Visual Areas..- 5.5.1 Rostral Thalamus.- 5.5.2 Caudal Dorai Thalamus.- 5.5.3 Praetectum.- 5.6 Electric Stimulation Experiments.- 5.7 Brain Lesion Experiments.- 5.8 Responses of Tectal Neurons to Monochromatic Light..- 6 Conclusions and Speculations on the Neural Guidance of Visual Behavior in Salamanders.- 6.1 Neural Guidance of Feeding Behavior.- 6.1.1 Prey Object Identification.- 6.1.2 Neural Mechanisms of Prey Recognition.- 6.1.3 Classification of Tectal Cells Involved in Prey Recognition.- 6.1.4 The Constitution of Tectal Response Properties.- 6.1.5 Tecto-Pretectal Interaction.- 6.1.6 The "Recognition Module" Concept.- 6.1.7 The Problem of Stimulus Size Recognition.- 6.1.8 Distance Estimation Mechanisms.- 6.1.9 Neural Guidance of the Feeding Sequence and the Problem of Sensori-Motor Integration.- 6.2 Enemy and Barrier Avoidance.- 6.3 Optomotor Behavior.- 6.4 Conclusion: What is Known and What is not yet Known About Neural Guidance of Visual Behavior in Salamanders?.- Abbreviations Used in Figures.- References.
