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This chapter discusses the general principles of visual coding. It covers the structure of sense organs; types of sensory coding; temporal coding; the geometry of visual space; coding primitives; higher-order sensory systems; and types of perceptual judgment.

This concluding chapter addresses some of the larger issues relevant to the ideas presented in this book. These issues include the purpose of feelings, the brain structures required in order to experience feelings and which species have them, the kinds of feelings that other species might experience, why feelings seem to propel behavior, and whether Watson—the computer that won the Jeopardy game—might ever experience feelings. The chapter then examines the concept of graded sentience. This concept seems to provide the basis for graded feelings of interoceptive conditions, depending on the level of refinement of the homeostatic motor and sensory systems.

Crustaceans are used as model systems for studying behavioral and physiological processes common to many animals. Crustaceans are especially attractive to neuroethologists since most of their behavioral repertoire is controlled by a nervous system of relatively low complexity readily accessible for a variety of experimental techniques. Many basic neural mechanisms were first discovered in crustacean preparations and have then been generalized to many other organisms. In several taxa of social crustaceans, communication signals of different modalities are exchanged between conspecifics. Incoming signals are received, relayed, and sometimes integrated by the peripheral nervous system. The underlying mechanisms have been intensively studied and are reasonably well understood. Presently, the experimental transition from research on the peripheral nervous system to the central brain areas of higher order processing has begun. This will significantly improve our understanding of how signals are integrated into adaptive behavioral responses, thus illustrating how nervous systems shape communication.

This chapter presents an overview of the evolutionary history of vertebrate brains, with a specific emphasis on the organization of sensory systems in the forebrain. Birds and mammals highly overlap in their brain-body ratios and significantly exceed those in most other vertebrate groups. Recent studies on cognitive abilities of birds, ingenious for their species-sensitive design, have revealed a very high level of such ability in a number of avian species. Since elevated cognitive abilities correlate with higher levels of consciousness in mammals, it is parsimonious to postulate that this correlation holds for other vertebrate groups, including birds.

Sensory systems are highly selective information gatherers, and the modulation of activity within sensory pathways plays an important role in filtering out redundant information, improving signal-to-noise ratios, and ensuring that, in the face of changing conditions, sensory circuits continue to extract information optimally. The neuromodulatory mechanisms used to achieve such goals are commonly shared across widely divergent species. In vertebrates, perception of sensory events relies on the transfer of information to the cerebral cortex of the brain, and all of the neurons that link sensory receptors at the periphery with the spinal cord, brainstem, thalamus, and cerebral cortex are potential targets for neuromodulation. Neuromodulators allow our perception of sensory inputs to be affected by levels of arousal, attention, and emotional stress, and they play a key role in mediating changes in sensory information processing as a result of experience.

After some general considerations, this chapter discusses the phylogenetic brain stratification (the mammal’s brain becomes the center of the analysis), and study the brain as a system for integrating information from different sources and for developing coordinated behaviors.

This introductory chapter begins with a brief discussion of the rationale and purpose of the book, which takes the view that influences from the receptive field (RF) surround, which form the basis of perceptual completion and other forms of contextual perception, and under some circumstances can become the engine of a remapping of sensory space upon cortex. An overview of the subsequent chapters is presented.

This chapter focuses on the importance of sensation and sensory modality in shaping mate choice, drawing on the substantial literature on the sensory ecology of mate choice. It outlines the important common features of all sensory systems. All of these common features can be used to explain chooser features downstream of sensation, through perception to the motor output of behavior. These shared features are what is most important in terms of our understanding of mate choice, but what draws our attention about mate choice is the diversity of ways in which it is accomplished. The chapter focuses on the particulars of how sensory systems work in each of the principal modalities. It concludes by addressing the relationship between sensitivity, sensory constraints, and mating preference.

Bats (order Chiroptera) exhibit wide-ranging differences in foraging ecology, morphology and behavior that often reflect the demands on their sensory systems. New World leaf-nosed bats (family Phyllostomidae) have a wide spectrum of feeding ecologies and sensory system specializations. The family consists of bats that are primarily nectarivorous (e.g., subfamily Glossophaginae), frugivorous (e.g., Stenodermatinae, Carolliinae), sanguivorous (Desmodontinae), and predatory (Phyllostominae). Phyllostomid brains typically have more balanced visual, olfactory, and auditory regions in relative size compared with other bat families. Within phyllostomid subfamilies, relative brain region volumes reflect feeding ecology and corresponding sensory specializations. For instance, phytophagous phyllostomids have larger visual and olfactory regions relative to predatory species, which in turn have larger auditory centers. This chapter uses this bat family to illustrate the influences that foraging ecology and diet selection have on the evolution of sensory systems and relative brain and brain region volumes. The diversity within this family makes it an excellent model group among bats—and mammals in general—from which to better understand sensory specializations, cognitive development, and brain evolution.

Neuropsychological evidence and how it strengthens the case for considering spatial coding as dependent on the integration and organization of multimodal inputs is the main concern of this chapter. The evidence on anatomical and physiological changes is reviewed here. The chapter first provides a rough outline of some of the relevant brain regions and sensory systems. The other sections in this chapter focus on hemisphere specialization, especially for spatial processing in parietal regions of the right cerebral hemisphere, the effects of early experience, and the convergence of inputs in spatial functioning.

This chapter discusses the question of whether there is a sixth sense or not, first introducing the domain of sensation and perception, and then considering the “sixth sense” as a form of balance for the five senses. It also briefly discusses the culturally specific construction of a sensorium, the five-senses model, and the taxonomy of nine sensory systems that was introduced during the nineteenth century, introducing the Anlo-Ewe, which is the focus of the study, and the study's interpretive framework and argument.

This chapter is an attempt to provide a common conceptual and computational framework for neurophysiologists and roboticians who are faced, in spite of their different motivation, with the similar problem of combining several signals issued from sensors having various geometrical and dynamical properties. For animals and robots, motion is a fundamental source of information about their interaction with the environment. Animals (and some robots, now) have at their disposal a dedicated sensory system, devoted to the detection of their own 3D movement: the vestibular system. However, the vestibular organs fail to detect self-movement at low frequency and have to be complemented by other information sources such as vision, proprioception, or efferent copies of motor commands. The visual system is particularly useful for estimating the displacement and the 3D shape of other mobile objects, as well as the 3D structure of the environment. Many theoretical studies have been proposed to account for the ability of biological organisms to perceive 3D movement, or to build robots that are able to move and avoid unexpected obstacles. One of the central question in this context is the way in which the various signals are fused, and, more generally, how the 3D processing of individual sensors may dynamically interact.

Like many biologic systems, one of the differentiating features of the head and neck is its mechanical intricacy. The head-neck system includes approximately thirty muscles; each spans multiple joints, and each joint has multiple degrees of freedom. The sensory system includes several radically different types of sensory organs. At first, this intricacy may seem tough, yet it must be confronted squarely if a deep comprehension of sensory-motor coordination is to be made. One aspect of sensory-motor coordination that is epitomized by the head-neck system is the general problem of coordinate transformations. The root of the problem is that several parts of the process of doing an action in response to sensory stimuli are each largely described in their own terms.

This chapter focuses on sensory systems of animals that are commonly involved in plant–animal communication. Animals perceive the world around them quite differently from humans. The spectral sensitivities to light reflected from objects around humans are different from those of most other animal groups. For example, birds and primates can discriminate flowers and fruits from their background by their colours over a range of tens of metres while insects can use the chromatic information of flowers only on a range of centimetres. Humans, however, perceive the smell of plants within a range of tens of metres. Perceptual differences among animals exist in all sensory modes. This chapter explains the ecological sensory differences of animals and the ways in which these senses are used to interact with the biochemistry of plants.

This chapter presents a general overview of the psychophysical approach to studying illusory perceptions in animals. The premise of this chapter is that psychophysical methods are indeed of unprecedented power in disclosing the functional properties of animal sensory systems. However, these powerful methods do not actually enable us to gain any privileged access to the private experiential world of animals, even if one exists. These methods do nevertheless enable us to embark on objective inquiries into the biological bases of perception and action.

This chapter discusses the structure and function of mechanosensory systems, particularly hydrodynamic sensory systems, in secondarily aquatic tetrapods. It suggests that secondarily aquatic tetrapods are sensitive to tactile information and are actively using mechanoreception for seeking information about their environment. It also describes how they use specialized tactile organs for hydrodynamic reception. These tactile organs include the touch papillae in reptiles to sense prey fish movements; the bill-tip organ of aquatic birds to detect buried prey in wet sediments; push rods in aquatic platypus, primarily associated with electroreception; and Eimer's organs in the skin of the snout of the star-nosed mole for the haptic detection and identification of prey systems. It also demonstrates the hydrodynamic receptor function of vibrissae found in aquatic mammals. Vibrissae of harbor seals, for example, respond to vibrations and are essential for detecting and tracking hydrodynamic trails.