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This chapter discusses how environmental parameters influence the physiology and behavior of rats and thus the experimental outcome. It considers lighting, humidity, airflow, noise, cage construction, diet, and social opportunity. Maternal influences, age at weaning, animal care, exercise regimens, and enrichment are also discussed. These factors can induce changes in brain weight, cerebral vascularization, adrenal size, and body weight.

This chapter discusses some of the methodologies used to measure rat vision, the known visual capabilities of rats, and the implications of rat vision for those researchers who use rats in vision-based experiments. Topics covered include experimental methods for measuring rat vision, the rat eye, spatial vision, and implications of rat vision for investigators.

This chapter describes maternal behavior of the laboratory rat and outlines various methods of observing and quantifying this behavior. Although in some rodent biparental species males also show parental behavior, this is not the case for most rodents, including R. norvegicus. However, under certain experimental conditions, males also show many of the components of behavior normally shown by the mother rat. The general and specific methods for the testing of maternal behavior are described. Several environmental and situational factors that affect the expression of maternal behavior are considered.

This chapter begins with a brief review of the literature on social influences on food choices of Norway rats. It describes fieldwork strongly suggesting that interactions between adult free-living rats and their young can determine which foods the young come to eat. It then describes several behavioral processes that have been shown in the laboratory to be sufficient to influence food choice in young rats. Finally, it discusses a type of social influence on rats' food preferences that has already proved to be useful in studies of the physical substrates of learning and memory.

This chapter provides an overview of the reproductive systems and the neural systems that mediate sexual behavior, and discusses how to study sexual behavior in male and female rats. It shows that the male and female rat share many commonalities in terms of the anatomical substrates of sexual behavior. Another common feature in the sexual behavior of males and females is the role that the striatum and nucleus accumbens (NAcc) play in mediating sexual behavior and motivation.

This chapter discusses the salient features of rat feeding behavior relevant to laboratory-based studies of this species. Topics covered include lifetime patterns of intake, daily patterns of intake, meal patterns, behavior that anticipates feeding, feeding and the behavior that follows feeding, diet choice, and neophobia and diet variety.

This chapter discusses aggressive behavior in rats. Aggressive behavior, although infrequent, is part of life in a colony, particularly during its formation, and these interactions within the group are referred to as dominance or within-group aggressive behavior. As in their feral counterparts, the most potent trigger for aggressive behavior in resident male laboratory rats is the intrusion by an unfamiliar adult male, and these interactions are called resident-intruder aggression. Aggressive behavior by a female resident is more likely in the initial postpartum period, at which time the dam attacks both male and female intruders (maternal aggression).

The “Norway rat” (Rattus norvegicus), known also as the “brown rat” is rivaled as a pest only by the house mouse (Mus domesticus vel musculus) and the “ship” or “black” rat (Rattus rattus). R. norvegicus also displays peculiar features that make it of special interest to both ethologists and experimental psychologists. This chapter provides an overview of the ecology of the wild R. norvegicus.

This chapter begins by describing the appearance of motor abilities, social and play behavior, sexual maturity, and sensory function in laboratory rats. It then discusses cognitive function, the development of simple stimulus associations made in conditioned taste aversion, and complex associations necessitated in spatial memory. The development of brain structures and their possible role in these behaviors are also discussed.

This chapter provides an overview of the seven main categories of behavioral assessment and describes some individual tests of behaviors in each category. It is broken into seven sections that provide overviews on a selection of behavioral tests useful in assessing that behavioral category. Representative references are provided for each test, but the reader is directed to specific chapters earlier in the book for more extensive reference lists. The test descriptions are intended to present a summary of a given test procedure rather than presenting the apparatus and procedural details; these can be obtained in cited methods references.

This chapter discusses the study of olfaction in rats. It argues that rats and other rodents live in an olfactory world and any attempt to understand rodent biology must take into account the importance of olfaction for social behavior, feeding, learning, and orientation in the environment. The role of odors in the control of rodent behavior has long been a primary topic in ethologically oriented studies of rat behavior, and the relatively simple tests used in these studies have served to demonstrate the influence and importance of odors. However, recent advances in odor control of learning and in the molecular biology of olfaction have required the use of more sophisticated test procedures and better control and understanding of the stimulus.

Studies with rats have been central to the understanding of postural support mechanisms. This chapter uses examples from this research to illustrate the importance of looking carefully at states of immobility, identifying the sensory controls guiding postural responses, and fractionating such responses into independent modules. For the latter, one type of postural support response, righting, is examined in detail to illustrate the need for using highly specific tests to evaluate these independent modules.

This chapter discusses foraging behavior in rats. It describes eating behavior, food protection and theft, food carrying, and some aspects of their neural control. The rich array of behaviors related to food handling in the rat provides a challenge to investigators of the neural control of behavior. Eating behavior can also be a useful measure in a wide range of studies, including those related to addiction, eating disorders, individual differences, and spatial and temporal behavior.

This chapter discusses defensive behavior in rats. Topics covered include specific defensive behaviors (e.g., flight, hiding, freezing, alarm cries, defensive attack), stimuli that elicit defense, the role of “expediting” stimuli in controlling specific defenses, the role of threat intensity in controlling specific defenses, outcomes of defensive behaviors, and laboratory models of rat defensive behaviors.

This chapter provides an overview of the contexts, mechanisms, and suggested functions of rat vocalizations. Topics discussed include frequency and temporal characteristics of vocalizations, environmental contexts associated with ultrasonic vocalizations, anatomical considerations, functional significance of ultrasonic vocalizations, and the vocalizing rat as a model of human psychological disorders.

This chapter discusses object recognition in rats. It describes the two paradigms most often used to assess object recognition in rats: delayed nonmatching-to-sample (DNMS) and novel-object-preference (NOP). It shows that despite superficial similarities, DNMS and NOP tests engage different behavioral and motivational systems and therefore entail different procedural pitfalls and interpretational challenges. Still, findings from lesion experiments using either task have so far been fairly consistent, suggesting that the hippocampus is not critical for object-recognition memory, whereas the perirhinal cortex plays a more significant role. These conclusions are consistent with findings of changes in single-unit responses and c-fos expression within the perirhinal cortex produced by repeatedly presented visual stimuli.

This chapter discusses the modeling of human pain in rats. Topics covered include models of chronic pain, behavioral reactions, stimulus and response, requirements for models of nociception, tests based on the measurement of reaction time for escape behavior, test based on the measurement of threshold for escape behavior, and tests based on the observation of behavior.

This chapter discusses the skilled movements of the laboratory rat. Topics covered include limb structure and movement, food handling, sensory control, reaching movements, arpeggio movement, strain differences in skilled movements, and skilled movement in neuroinvestigation and disease.

This chapter presents brief overviews of the growth of the Norway rat pup and differentiation of behavioral systems. There follows a kind of “ethogram” of early postnatal behavior in Rattus norvegicus, intended to put into a more natural context some of the processes of sensory and motor development, with an emphasis on information that can be used for designing and interpreting tests with immature rats.

This chapter describes behavioral tests that have been useful for examining the potential clinical efficacy of interventions that might be beneficial for neurological disorders. It is important to distinguish whether an intervention promotes brain repair mechanisms, saves cells, enhances motor learning and retraining, or reduces the extent of secondary degeneration of tissue. The chapter includes a subset of sensorimotor tests that are considered to be reliable, sensitive, quantitative, and easy to use in rat neurological models. The tests also cover the range of cellular degeneration typical of focal ischemic injury, nigrostriatal terminal loss, and cervical spinal trauma.