It may be that one of the most important criteria of the fundamental nature of research is precisely its apparent nonobviousness, its seeming uselessness, and evident contradictoriness to common sense.
In America by the 1930s, albino rats had become a kind of generic standard in research on physiology and behavior that de-emphasized diversity across species. However, prior to about 1915, the early work of many of the pioneer rat researchers in America and in central Europe reflected a strong interest in species differences and a deep regard for diversity. These scientists sought broad, often medical, generality, but their quest for generality using a standard animal did not entail a de-emphasis (...) of organic diversity. They chose white rats as test animals for two primary reasons. First, rats develop very slowly. They therefore made features of physiological, neural and psychological development accessible to the experimental method at a time when its application to the phenomena of development remained controversial. Secondly, rats were thought to have unusually strong sex drives. For this reason they became central to the experimental study of sexuality and, in the work of the reproductive physiologist Eugen Steinach, sexual development. Connections among three research institutes that stressed experimental approaches to the study of brain and development demonstrate the importance of the rat's institutional role. As the emphasis on experimentation in the study of development grew, two of these institutes bred rats to provide uniform materials. Eventually, however, their reasons for selecting rats were lost; and the ready availability of a uniform test animal led to a shift in scientists' presumptions about diversity, as the standard rat became a tool for assuring generality. (shrink)
Since at least the mid-1980s claims have been made for rationality in rats. For example, that rats are capable of inferential reasoning (Blaisdell, Sawa, Leising, & Waldmann, 2006; Bunsey & Eichenbaum, 1996), or that they can make adaptive decisions about future behavior (Foote & Crystal, 2007), or that they are capable of knowledge in propositional-like form (Dickinson, 1985). The stakes are rather high, because these capacities imply concept possession and on some views (e.g., Rödl, 2007; Savanah, 2012) rationality (...) indicates self-consciousness. I evaluate the case for rat rationality by analyzing 5 key research paradigms: spatial navigation, metacognition, transitive inference, causal reasoning, and goal orientation. I conclude that the observed behaviors need not imply rationality by the subjects. Rather, the behavior can be accounted for by noncognitive processes such as hard-wired species typical predispositions or associative learning or (nonconceptual) affordance detection. These mechanisms do not necessarily require or implicate the capacity for rationality. As such there is as yet insufficient evidence that rats can reason. I end by proposing the ‘Staircase Test,’ an experiment designed to provide convincing evidence of rationality in rats. (shrink)
In 1920, Eugen Steinach and Paul Kammerer reported experiments showing that exposure to high temperatures altered the structure of the gonad and produced hyper-sexuality in "heat rats," presumably as a result of the increased production of sex hormones. Using Steinach's evidence that the gonad is a double gland with distinct sexual and generative functions, they used their findings to explain "racial" differences in the sexuality of indigenous tropical peoples and Europeans. The authors also reported that heat induced anatomical changes (...) in the interstitial cells of the gonad were inherited by the heat rats' descendants. Kammerer used this finding to link endocrinology to his long-standing interest in the inheritance of acquired characteristics. The heat rats supported his hypothesis that the interstitial cells of the double gland were the mechanism of somatic induction in the inheritance of acquired characteristics. The Steinach-Kammerer collaboration, Kammerer's use of Steinach's "puberty gland" to explain somatic induction, and his endocrine analysis of symbiosis reveal Paul Kammerer's late career attempt to integrate endocrinology and genetics with the political ideals of Austrian socialism. With them he developed a bioethics that challenged the growing reliance on race in eugenics and instead promoted cooperation over competition in evolution. I relate his attempt to the controversies surrounding the interstitial cells, to the status of extra-nuclear theories of heredity, and to Kammerer's commitment to Austromarxist social reforms during the interwar period. (shrink)
Mitchell et al. contemplate the possibility of rats being capable of propositional reasoning. We suggest that this is an unlikely and unsubstantiated possibility. Nonhuman animals and human infants do learn about the contingencies in the world; however, such learning seems not to be based on propositional reasoning, but on more elementary associative processes.
: A major shortcoming of the Animal Welfare Act is its exclusion of the species most-used in experimentation-rats, mice, and birds. Considerations of justice dictate that extension of the law to these three species is the morally right thing to do. A brief history of how these species came to be excluded from the laws protecting laboratory animals is also provided, as well as discussion of the implications and significance of expanding the law.
The Effect of Stressor Level Grading on the Stimulus Seeking Behavior of Rats Differing in Emotional Reactivity1 A natural disaster — such as a flood — is a sequence of events: swollen water level leading to the flooding of homesteads — primary stressor and later environmental consequences — secondary stressor syndrome. In order to be valid, an experimental model must ensure similarity of the stress-evoked behavioral symptoms. The most frequently administered behavioral tests measure exploratory behavior in the broad sense. (...) We also included emotional reactivity in the experimental design in order to test the idea that lower emotional reactivity alleviates the consequences of stress and therefore acts preventively. Reduced emotional reactivity and increased stressor intensity additively contribute to increased exploratory behavior. A main handling effect is found for most indices of emotional behavior. The proposed experimental model seems to meet two important criteria: it has face validity and it evokes very clear behavioral consequences, ones which are universal for most indices of exploratory behavior. (shrink)
This paper investigates the way in which the sexuality of women has been posited in relation to rats as experimental subjects, exploring the stakes of a scientific debate that takes the social world of female sexuality as its focus and as a political problem. Studies that purport to understand female sexuality by investigating rat behavior rely on problematic assumptions about sovereign agents motivating sexual behavior. Such studies also aim to do away with so-called deviant sexual behaviors and, as a (...) consequence, gay people. Theories of agential realism and hybridity serve as counterforces to these inherently repressive perspectives by insisting on the multiple determinations of sexuality and subjectivity among women. (shrink)
Warsaw Wild Captive Pisula Stryjek rats - Establishing a breeding colony of Norway Rat in captivity It is believed that the history of laboratory rat dates back to 1820-ies, which is about 300 generations. This relatively short evolutionary distance, drastically different environment and selective breeding could have caused differences in behaviour between the laboratory rat and his wild counterpart - Norway rat. The vast majority of research concerning differences between wild and laboratory rats was conducted over 30 years (...) ago. The knowledge acquired as a result of that research seems far from being complete. Over a quarter of a century could have deepened the described differences. Nowadays the change in experimental approach, in favour of low stress conditions, can give a new insight into this problem. This article describes process of establishing a laboratory line of wild Norway rat, which will take part in a broad series of comparative studies. 16 wild rats were trapped in 5 distant parts of Warsaw. Most of wild rats successfully adapted to captive conditions, mating successfully and producing litters, which have survived to adolescence. (shrink)
The effects of handling on the exploratory activity of rats in settings varying in level of sensory stimulation1 This study tests the assumptions of need for stimulation theory. According the main hypothesis of this theory, the stimulus seeking activity of an organism in an unfamiliar environment is affected by two main temperamental traits: emotional reactivity and need for stimulation. In a familiar setting, the influence of emotional reactivity disappears, while the need for stimulation persists. Two experiments were run in (...) which animals' emotionality was manipulated by means of presence or absence of handling and the level of environmental stimulation was manipulated by varying the intensity of light to which the animals were exposed. Sixty male Wistar rats were tested in the first experiment. Stimulus seeking activity was registered in the Skinner-type chambers where animals could switch the light on by every head dip into one of two holes, the so-called experimental hole. Animals were tested in five 30-minute sessions repeated every 48 hours. As predicted, the effect of emotionality on exploration emerged at the beginning of the experiment, whereas the effect of the level of environmental stimulation on the total number of head-dips emerged in all the experimental sessions. The second experiment involved 40 rats and followed a similar design, but the stimulus seeking activity was measured in the situation where the animals could switch the light off by dipping their heads into the experimental hole. Contrary to predictions, the experimental factors had no significant effect on the animals' stimulus seeking activity. Only the results of the first experiment confirm the assumptions of need for stimulation theory. (shrink)
Response to novelty in rats tested in isolation and in pairs: focus on exploration and play The main goal of the study was to compare investigatory responses towards novelty in 20 Wistar rats divided into two experimental groups. Additionally, relationship between novelty and social play/interaction was analyzed in the dyad group. Procedure involved placing animals in an experimental chamber during fifteen, six minute trials on successive days of the study. On the eleventh session a new object was introduced. (...) The results are summarized within several behavioral categories. Investigatory responses of rats in dyad to novel object in familiar environment were not quantitatively different, than those of isolated animals. The animals from both groups responded to the novel object by focusing their exploratory activity on the source of new stimulation. Amount of social play and social exploration was influenced by the experimental manipulation with important sex differences present. (shrink)
Response to spatial and nonspatial change in wild and Wistar rats The purpose of the experiment was to investigate the effects of domestication on exploration in rats. The comparison was made between wild Warsaw-Wild-Captive-Pisula-Stryjek rats and Wistar laboratory rats. The study used a purpose-built maze divided into zones connected with a corridor. Objects were placed in two out of four zones. Their location and shape were subject to experimental manipulation. Transporter used to move rats to (...) the maze provided the opportunity for spontaneous exploration of the experimental arena. Rats were subjected to a series of 10 sessions, followed by a spatial or nonspatial change in the experimental arena, after which another 5 experimental sessions were conducted. The study revealed that wild rats had much higher exploration latency than their laboratory counterparts. At each analyzed stage, WWCPS rats spent much more time in the transporter than Wistar rats. Wistar rats spent much more time during the experiment on object interaction in the experimental arena. In post-manipulation sessions, however, it was wild rats that explored object zones relatively longer than laboratory rats. No differences in the animals' behavior depending on the type of change were observed. Results suggest that wild rats tend to explore much more cautiously than laboratory rats and are more sensitive to changes in their environment. The underlying cause of these differences is likely to be the higher level of stress in wild rats, resulting from threats in their natural habitat. (shrink)
Hypocretin regulates brain reward function and cocaine consumption in rats. The hypocretinergic (Hcrt) system is implicated in energy homeostasis, feeding and sleep regulation. Hypocretinergic cell bodies are located in the lateral hypothalamus (LH) and project throughout the brain. The aim of the present studies was to investigate the role of the Hcrt system in regulating brain reward function and the reinforcing properties of cocaine in rats. Intracranial self-stimulation (ICSS) thresholds provide an accurate measure of brain reward function in (...)rats. Here we show that a single injection of Hcrt-1 (5 µg icv) induced persistent, long-lasting elevations in ICSS thresholds in drug-naïve rats. Indeed, Hrct-1 elevated ICSS thresholds for 36 h, with peak elevations between 6 and 12 hours after injection. Hrct-1-induced threshold elevations were attenuated by an antibody known to neutralize the binding of hcrt-1 to its receptors. Taken together, these observations suggest that Hrct-1 negatively regulates brain reward function in rats. Because Hrct-1 negatively regulates brain reward function, we hypothesized that it may attenuate the increased brain reward function usually observed after cocaine consumption, and thereby alter cocaine self-administration behavior. A daily injection of Hrct-1 (1 µg icv), for 4 consecutive days, slightly increased cocaine self-administration (0.25 mg/infusion) in rats. Overall, these data demonstrate that Hrct-1 negatively regulates brain reward function, and as such may indirectly alter cocaine self-administration. Given the well-established role of hypocretin neurons in regulating feeding behavior and sleep, we hypothesize that hypocretinergic regulation of brain reward function may provide a mechanism by which appropriate and competing behaviors (e.g. sleep or feeding) may be engaged to maintain energy homeostasis. (shrink)
Elevations in brain stimulation reward (BSR) thresholds have been observed in rats undergoing nicotine withdrawal and have been proposed as a sensitive measure of the negative affective state associated with nicotine withdrawal. mGluR are presynaptic autoreceptors that decrease glutamate release when stimulated. The aim of this study was to examine the role of glutamate neurotransmission in nicotine dependence. The mGluR agonist LY314582 (2.5–7.5 mg/kg) precipitated nicotine withdrawal as measured by elevations in BSR thresholds in nicotine-treated rats but not (...) in controls. It was hypothesized that LY314582 precipitated nicotine withdrawal by decreasing glutamatergic tone at postsynaptic glutamate receptors. Therefore, the effects of MPEP (0.5–2 mg/kg), an mGluR antagonist, and MK-801 (0.01–1 mg/kg), an NMDA receptor antagonist, were examined. MPEP elevated BSR thresholds by an equal magnitude in control and nicotine-treated rats. At low doses, MK-801 (0.01–0.2 mg/kg) lowered BSR thresholds to a similar extent in control and nicotine-treated rats. At higher doses, MK-801 (0.25–1 mg/kg) disrupted performance in nicotine-treated and control rats. These data indicate that mGluR and NMDA receptors regulate BSR in opposite directions in non-dependent animals, and chronic nicotine treatment does not alter these effects. Most importantly, the data demonstrate that the mGluR is involved in nicotine dependence, but mGluR and NMDA receptors do not mediate mGluR actions in nicotine dependence. (shrink)