This chapter looks at the active orientation mechanisms developed by some animals. The chapter focuses on echolocation, a mechanism to negotiate an animal's surroundings based on the emission of sound, its reflection by objects located within the emission beam, and the analysis of the returning echo. Echolocation has been found in bats, toothed whales, and oilbirds. The chapter revisits the beginning of echolocation research at the end of the eighteenth century when several scientists conducted a series of experiments on how bats orient in the dark. It describes the two major categories of sounds produced by bats: frequency-modulated (FM) signals which are used to estimate the distance of the bat from an object, and constant-frequency (CF) signals which are well suited for the so-called Doppler shift analysis. Lastly, the chapter discusses the adaptations developed by some insects to counteract bat echolocation.
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Active orientation and localization
Chapter
Attention
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter focuses on the phenomenology of attention, its effects on sensory systems, and the neural systems that support its deployment. Endogenous attention refers to the ability to voluntarily direct attention based on one's goals, expectations, or knowledge. Meanwhile, exogenous attention refers to involuntary shifts of attention triggered by salient stimuli in the environment. Both lead to enhanced processing of the information to which attention has been directed. Recent research has identified a frontal-parietal network whose activity is associated with the engagement of attentional processes, as when a stimulus indicates the need to shift attention from one location in space to another. Ultimately, damage to cortical and subcortical regions can lead to deficits in attentional processing that have important clinical consequences.
Book
Günther K. H. Zupanc
Behavioral Neurobiology starts off with an introduction. The next chapter presents the fundamentals of neurobiology. The text also gives a brief history on the study of animal behavior and its neural basis, and examines orienting movements. Other topics covered include active orientation and localization, the neuronal control of motor output, the neuronal processing of sensory information, and sensorimotor integration. The text then goes on to consider neuromodulation and the accommodation of motivational changes in behavior, circadian rhythms and biological clocks, and large-scale navigation in terms of migration and homing, communication, and cellular mechanisms of learning and memory.
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Cellular mechanisms of learning and memory
This chapter focuses on the cellular mechanisms that underlie the memory stage. It explains amnesia, or the disturbance in long-term memory, manifested by total or partial inability to recall past experiences. The discussion distinguishes between anterograde amnesia and retrograde amnesia. The chapter then describes the two types of memory: explicit and implicit memories. It tackles the sensitization in the marine mollusk Aplysia as a model system to explain the cell biology of an implicit memory system. It discusses the neural circuit of the gill-withdrawal reflex and the molecular biology of both short-term and long-term sensitization. Furthermore, the chapter zooms in on the hippocampus of mammals and birds as a model to study the cell biology of an explicit memory system — explaining the concepts of long-term potentiation and adult neurogenesis.
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Circadian rhythms and biological clocks
This chapter addresses questions about how rhythms in animal behaviors and physiological activities are generated. It first looks at some of the major behavioral characteristics of rhythmic patterns occurring daily and finds out how the observations made during these studies have led to the concept of biological clocks. The discussion touches on the discipline of chronobiology, which examines biological rhythm. The chapter also explores the molecular structure of these clocks and discusses how the individual clock components integrate to produce an oscillatory output. Lastly, the chapter summarizes what is known about the localization of biological clocks at a systems level.
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Cognitive Functions and the Organization of the Cerebral Cortex
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter discusses cognitive functions and the organization of the cerebral cortex. It shows how different association cortices contribute to different functions. The parietal association cortex is involved in attention and awareness of the body and the stimuli that act on it. The temporal association cortex is involved in the recognition and identification of highly processed sensory information. Meanwhile, the frontal association cortex is involved in guiding complex behavior by planning responses to ongoing stimulation (or remembered information), matching such behaviors to the demands of a particular situation. The especially extensive association cortices in our species compared with those of other primates support the cognitive processes that define human culture.
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Communication
This chapter reviews the biological definition of communication and some of the sensory modalities involved in the detection of communication signals. It explains the concepts of true communication and mutualism, as well as the sensory modalities involved in communication. The discussion covers visual, acoustic, chemical, tactile, and electrical signals. Furthermore, the chapter focuses on two intensively studied model systems. One of the model systems is the neuroethology of cricket song where the mechanism and neural control of sound production are examined, and the concept of positive phonotaxis is explained. The discussion covers the use of Kramer locomotion compensator, the song recognition by auditory interneurons, as well as the effect of temperature on calling songs of crickets. The second model system explains the development of bird songs — describing the neural circuits for song perception, song production, and song learning.
Chapter
Construction of Neural Circuits
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter studies the construction of neural circuits. Once nerve cells have been generated, groups of neurons must become interconnected to form the neural circuits that mediate brain function. The first step in this process is to establish axons and dendrites in the newly generated neurons. The specification and growth of the characteristic single axon from a newly generated neuron, and the parallel specification and growth of dendrites, depend on cell polarity. In the developing neuron, polarity reflects local signals that are available to one region or another of the developing neuron. These signals then elicit changes in the neuronal cytoskeleton that distinguish growing axons from dendrites. The directed growth of axons and their recognition of appropriate synaptic targets depend on a leading process of the growing axon called a growth cone. Once axons find their way to appropriate targets and form synapses, molecular neurotrophic factors influence neuron survival.
Chapter
Cortical States
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter examines how the brain and the rest of the nervous system regulate changes across cortical states, and how this physiological regulation contributes to consciousness and awareness. Nearly all animals exhibit a restorative cycle of rest following daily activity, but only some animals organize the period of rest into distinct phases of non-REM and REM sleep. A complex physiological interplay involving the brainstem, thalamus, and cortex controls the degree of mental alertness on a continuum from deep sleep to wakeful attentiveness. A circadian clock located in the suprachiasmatic nucleus of the hypothalamus in turn influences these systems, adjusting cortical and other physiological states to appropriate durations during the 24-hour cycle of light and darkness that is fundamental to life on Earth. Recent research seeks to understand the puzzling question of why large regions of the cortex are more active at rest than when an individual is performing a task.
Chapter
Early Brain Development
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter explores early brain development. The elaborate architecture of the adult brain is the product of cell-to-cell signals, genetic instructions, and their consequences for stem cells that are set aside in the embryo during the earliest steps of development to generate the entire nervous system. These events include the establishment of the primordial central and peripheral nervous systems, the initial formation of the major brain regions, the generation of multiple classes of neurons and glial cells from undifferentiated neural stem or progenitor cells, and the migration of neurons or their immediate precursors from sites of generation to their final positions. These processes set the stage for the subsequent local differentiation of dendrites, axons, and synapses, as well as the growth of long-distance axon pathways and synaptic connections. When any of these processes goes awry, the consequences can be disastrous.
Chapter
Electrical Signals of Nerve Cells
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter discusses how nerve cells generate a variety of electrical signals that transmit and store information. Although neurons are not intrinsically good conductors of electricity, they have elaborate mechanisms that generate electrical signals based on the flow of ions across their plasma membranes. Ordinarily, neurons generate a negative potential, called the resting membrane potential, which can be measured by recording the voltage between the inside and outside of nerve cells. The action potential is a fundamental electrical signal that transiently abolishes the negative resting potential and makes the transmembrane potential positive. All of these electrical signals arise from ion fluxes brought about by the selective ion permeability of nerve cell membranes, produced by ion channels, and the non-uniform distribution of these ions across the membrane, created by active transporters. Potassium ions generate the resting membrane potential, while action potentials arise from sequential changes in sodium and potassium permeability.
Chapter
Emotion
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter explores emotions, which are critically important for human behavior. Emotion-induced changes in body states are mediated by the visceral motor nervous system, which is itself regulated by inputs from many other parts of the brain. Behavioral changes associated with emotion are governed by a diverse set of brain structures, most notably the amygdala but also the hypothalamus and several regions of the cerebral cortex. Many clinical conditions are associated with dysfunctional emotional processing: the dampening of affect in depression, the disordered perception of emotional expressions following medial temporal damage, and the exaggerated reactions to stimuli by individuals with PTSD, among many others. Neuroscientists now see emotion as intertwined with cognitive processes such as attention, memory, and decision making.
Chapter
Experience-Dependent Plasticity in the Developing Brain
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter highlights the final phase of brain development, which relies on cellular changes driven by electrical activity in neurons, including synaptic and action potential activity, most often elicited by environmental stimuli that reflect the newborn's experience of their environment. The limited times of postnatal developmental change elicited by electrical activity in specific circuits are referred to as critical periods. The cellular and molecular mechanisms that mediate activity-dependent developmental changes are in many ways similar to those that mediate synaptic modifications that underlie learning and memory. Many of the effects of activity during circuit development depend on secreted signals, including neurotransmitters and growth factors, transduced via second messengers and their effectors. These activity-elicited changes influence local gene expression and trophic interactions that lead to final adjustments of axon or dendrite growth, as well as synapse growth and stability.
Chapter
Eye Movements and Sensorimotor Integration
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter addresses the major features of eye movement control to illustrate principles of sensorimotor integration. The reticular formation of the pons and midbrain provides the basic circuitry that mediates movements of the eyes. Descending projections from upper motor neurons in the superior colliculus and the frontal eye field innervate gaze centers in the brainstem, providing a basis for integrating eye movements with sensory information that indicates the location of visual targets. The superior colliculus and the frontal eye field are organized in a parallel as well as a hierarchical fashion, enabling one of these structures to compensate for the loss of the other. Eye movements, like other movements, are also under the control of the basal ganglia and cerebellum; this control ensures the proper initiation and successful execution of these relatively simple motor behaviors, thus allowing observers to interact efficiently with the visual environment.
Chapter
Fundamentals of neurobiology
This chapter introduces the fundamentals of neurobiology, specifically the concepts and methodologies that are of immediate relevance to behavioral neurobiology. It discusses the cellular and subcellular composition of nervous systems – comparing cell theory and reticular theory. The discussion covers the Golgi method, an histological staining technique invented by Camillo Golgi, as well as the work of Spanish neurohistologist Santiago Ramón y Cajal who further improved the staining technique and applied it to many parts of the nervous system, providing strong evidence in support of cell theory. Furthermore, the chapter explains the salient features of neurons and nervous systems, the axons ensheathment by myelin, and the physiology and ionic basis of the electrical properties of neurons. It describes synapses, the specialized contact zones in the nervous system where a neuron communicates with another cell. The chapter also gives a glimpse of some neurobiological approaches in neuroethology.
Chapter
Hearing
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter explores the auditory system, which processes multiple key aspects of sound, most notably frequency and location. Our sensitivity to sound frequency is critical for our ability to perceive speech and music, and is based on a combination of resonance gradients in the cochlea and temporal synchronizing of neural activity to the periodic cycles of a sound wave. Anatomically, the auditory pathway is characterized by feedforward and feedback pathways, and involves both crossed and uncrossed pathways. The chapter then looks at the process of sound localization. Coordination between vision and hearing is critical to auditory perception, and involves incorporation of information about movements of the eyes with respect to the head and ears at multiple levels of the auditory pathway.
Chapter
Introduction
This chapter gives an overview of neuroethology, the biological discipline that attempts to understand how the nervous system controls the natural behavior of animals. It emphasizes that this area of study has its roots in both neurobiology and ethology, and that its success is based on the incorporation of a blend of the neurobiological and ethological approaches into its own scientific armory. The chapter introduces ethogram, which refers to the entire behavioral repertoire of an animal species. Then it discusses how behavioral patterns are quantified using their rate of occurrence, duration, and/or intensity. The chapter also considers how to select a suitable model system for neuroethological research. These systems are characterized by behavioral patterns that, although simple, robust, and readily accessible, are also ethologically relevant.
Chapter
Ion Channels and Transporters
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter investigates how the generation of electrical signals in neurons requires that plasma membranes establish concentration gradients for specific ions and that these membranes undergo rapid and selective changes in their permeability to these ions. The membrane proteins that create and maintain ion gradients are called active transporters; other proteins, called ion channels, give rise to selective ion permeability changes. Ion channels are transmembrane proteins that contain a narrow pore that selectively permits particular ions to permeate the membrane. Different combinations of ion channels are found in different cell types, yielding a wide spectrum of electrical characteristics. In contrast to ion channels, active transporters are membrane proteins that produce and maintain ion concentration gradients. From the perspective of electrical signaling, active transporters and ion channels are complementary: Transporters create the concentration gradients that help drive ion fluxes through open ion channels, thereby generating electrical signals.
Chapter
Large-scale navigation: Migration and homing
This chapter focuses on long-distance migrations of animals, introducing some key concepts of these phenomena. It discusses different modes of migration and briefly reviews previous experiments on the genetic control of migratory behavior. The chapter also explains homing, or the ability of an animal to specifically return to the place it considers home. Then it takes a closer look at the general methods used to study animal migration, including the use of tags, radar, and microtransmitters, and satellite-based radiotelemetry. Moreover, the chapter provides a detailed discussion of the behavioral, sensory, and neural mechanisms involved in orientation during migration and homing, using representatives of two particularly well-studied animal groups — birds and fish.
Chapter
Lower Motor Neuron Circuits and Motor Control
Edited by George J. Augustine, Jennifer Groh, Scott Huettel, Anthony-Samuel LaMantia, Leonard E. White, and Dale Purves,
This chapter investigates how skeletal muscle contraction is initiated by “lower” motor neurons in the spinal cord and brainstem. The cell bodies of the lower neurons are located in the ventral horn of the spinal cord gray matter and in the motor nuclei of the cranial nerves in the brainstem. These neurons send axons directly to skeletal muscles via the ventral roots and spinal peripheral nerves or, in the case of brainstem motor nuclei, via cranial nerves. The spatial and temporal patterns of activation of lower motor neurons are determined primarily by local circuits located within the spinal cord and brainstem. The local circuit neurons receive direct input from sensory neurons and mediate sensorimotor reflexes. They also maintain precise interconnections that enable the coordination of a rich repertoire of rhythmical and stereotyped behaviors.
