A simple transmitter mount for short-term telemetric measurement of heart rate in the rat

This article describes a simple technique, not involving surgery, for mounting a small telemetry transmitter on a laboratory rat. The method is useful for collecting heart-rate data in studies of 2 or 3 days’ duration.     

A simple technique for delivering liquids directly to the mouth of an unrestrained rat

A simple surgical procedure is described that makes it possible to deliver liquids directly into the mouth of a freely mobile rat. Data presented show that an 8% sucrose solution delivered by this technique is an effective reinforcer in a variety of simple and discriminative schedules of reinforcement.     

Analysis of arterial blood gases in the curarized,artificially respira ted rat

The present paper describes a simple and accurate technique for the artificial respiration of curarized rats that avoids the trauma involved in a tracheotomy. Success of the technique depends on the proper positioning of a special face mask on the rat. The results of an experiment on arterial blood gases in 48 curarized rats are presented to illustrate the accuracy and effectiveness of the techniques described.     

Babies by bar-press: Maternal behavior in the rat

Pregnant rats were trained to press a bar for food rewards: Postpartum these Ss were tested when each bar-press delivered a rat pup (S’s own or foster) into the food cup. Ss repetitively bar-pressed, snatched up the pup as it tumbled down the chute and retrieved the pup into the adjacent nest box. Ss lived with 6 nursing pups but bar-pressed for hundreds: E removed all but 6 pups from the nest box after S had accumulated about 20. Maximal performance was 684 responses in a 3-h period. This technique is currently being used to study weaning and hormonal factors involved in the rat’s maternal motivation.     

Second-order conditioning of Pavlovian conditioned inhibition

Two experiments are reported which investigated the conditioning of inhibition to a neutral stimulus as a result of its repeated pairing with a previouslyconditioned inhibitor. Both experiments employed a conditioned suppression technique with rat subjects. Experiment 1 detected the second-order inhibition through the retarded acquisition of concurrently administered excitatory conditioning. Experiment 2 found similar retardation in the acquisition of excitatory fear conditioning following previous second-order conditioning of inhibition to the stimulus. Implications are discussed for theories of the nature of inhibition and for second-order conditioning as an assessment technique.     

Prenatal expression of species-typical action patterns in the rat fetus (Rattus norvegicus)

We investigated sensory and behavioral responsiveness of the rat fetus. On Days 19, 20, or 21 of gestation, rat fetuses received intraoral infusions of a biologically important stimulus, milk, or a novel chemical stimulus, lemon. Using a technique to directly observe behavior in utero, we found that rat fetuses discriminate between intraoral infusions of milk and lemon, exhibiting different levels and patterns of overall activity after infusion. Milk was found to evoke a low magnitude, delayed increase in overall fetal activity from Day 19 through Day 21, whereas lemon evoked a high-magnitude, spiked pattern of activity that diminished from Day 19 to Day 21. Late in gestation these two stimuli elicited species-typical action patterns. Milk infusions elicited a stretch response much like the one shown by pups at the nipple; lemon infusions elicited face wiping typical of older pups and adults exposed to aversive gustatory stimuli.     

A technique for chronic recording of systemic arterial blood pressure in the unrestrained rat

A technique is described for the chronic recording of systematic arterial blood pressure, respiration, and heart rate in the unrestrained rat. The surgical implantation and anchoring procedures described are compatible with the delivery of noxious electric shock and/or rewarding intracranial brain stimulation as reinforcement. Data on catheter patency are analyzed in 65 rats participating in a variety of experiments on the instrumental and classical conditioning of blood pressure responses. The results indicate that it is difficult to maintain satisfactory catheter performance beyond 2 weeks.     

The intercalated reinforcement technique: Learning without differential total reinforcement between groups

An intercalated reinforcement technique is described. The method equates number of trials, response topography, sensory exposure, and frequency of reinforcement between reversal Ss overtrained on a discrimination and then trained on reversals and nonreversal Ss similarly overtrained but continued on the same discrimination. In extending previous successful work in the rat, monkeys were trained on spatial discrimination and reversal tasks in the WGTA at 50%, 75%, and 100% reinforcement in order to test the efficacy of learning by this procedure, and to compare the method with learning obtained by a more classical procedure. Learning rates were the same by both procedures. This technique, therefore, appears useful for investigating neurochemical (or other) correlates of learning unconfounded by performance or sensory effects.     

Some properties of conditioned and unconditioned eyelid reflexes in the albino rat

Eyelid responses in the rat were recorded as electromyographic activity (EMG) or as movements detected by a photoelectric technique. Spontaneous blinks, startle responses to acoustic stimuli, unconditioned responses to air puffs, and conditioned responses based on the corneal reflex were recorded under a variety of conditions. Special attention was given to topographical and temporal characteristics of the responses. Some relationships between the EMG and eyelid movements are described, as well as changes in eyelid responses related to habituation, conditioning, and various stimulus manipulations, In addition to the substantive findings, the study suggests that the rat may yet become a useful S in the study of eyelid conditioning.     

Effects of response pacing on conditioned suppression

In this experiment, which employed a balanced design with two rat subjects, the frequency of reinforcement remained constant while the rate of operant responding was varied by means of a response pacing technique. At each of three response rates, 1-min. periods of noise were presented, and, as these periods ended, a slight unavoidable shock was delivered to the rat. This procedure resulted in suppression of the operant responding during the periods of noise. This behavioural change was measured by a suppression ratio, essentially a comparison of the response rates in the presence and absence of the noise. The suppression ratios varied in a systematic way during the experiment, denoting most conditioned suppression when the baseline rate of responding was high, and least suppression when this was low. It is therefore concluded that response rate in one factor determining the degree of conditioned suppression in this controlled experiment. The conclusion is corroborated by absolute measures of responding during the pre-shock periods of noise.     

Cytoarchitecture and histochemical fluorescence studies of the cingulate cortex in the rat

The cingular cortex of the rat was examined by means of Golgi's rapid impregnation technique, the glyoxylic acid technique for the detection of biogenic amines and a ninhydrin reaction in the octanoic milieu for the detection of GABA. Six interneuron types are described, differing with respects to their dendrite configurations and axon morphology. The noradrenaline innervation shows considerable differences as compared to the dopamine fibre system. GABA-containing neurons of various shapes and sizes are concentrated in the laminae II and III. The findings are discussed in connection with the conception according to the which the Gyrus cinguli as part of the limbic system might play a role in the genesis of psychopathological processes.     

Instrumental conditioning of scratching in the laboratory rat

Experiment 1 demonstrates that scratching in the laboratory rat can be instrumentally conditioned with food reinforcement. However, the asymptotic rate of performance of this response is shown to be low, as compared with an instrumental lever press response. It is suggested that one reason for this low rate of responding is that the scratch response can only be performed in the presence of an infrequently occurring itch stimulus. In support of this account the remaining experiments demonstrate that the rate of instrumental scratching can be increased relative to that shown by control groups by using a technique which might be supposed to increase the frequency at which an itch stimulus occurs.     

Detailed analysis of the male copulatory motor pattern in mammals: hormonal bases

Data obtained, using a polygraphic technique, on the characteristics of the motor and genital copulatory responses of male rabbits, rats, mice, hamsters, and guinea pigs are reviewed. This methodology provided detailed information, not accessible to other analyses, on the frequency and dynamic organization of copulatory pelvic thrusting trains of the species studied. This comparative analysis showed that: (1) The male rat may display two types of ejaculatory responses, differing in the dynamic organization of the pelvic thrusting train, and in the duration of the intravaginal thrusting period preceding ejaculation. (2) In the guinea pigs and small rodents, but not in rabbits, pelvic thrusting at ejaculatory responses persists during intromission, and a period of fast intravaginal thrusting is associated with ejaculation. (3) The motor copulatory pattern of the rabbit, but not of the rat, hamster, or guinea pig, is affected by castration and hormone treatment, suggesting that, in rabbits, androgen acts both on motivation and on the spinal neural systems related to copulation.     

Interspecific aggressiveness and reactivity in mouse-killing and nonkilling rats: Compared effects of olfactory bulb removal and raphe lesions

The experiments aimed at uncovering possible correlations between inter-specific aggressiveness and general and emotional responsiveness (appraised by means of the open-field technique) in the rat. Killer rats showed a higher level of emotional responsiveness than nonkillers. Removal of the olfactory bulbs induced an increased reactivity both in the rats which were converted into killers in those whose behavior toward mice remained unchanged. Destruction of the dorsal and medial nuclei of the raphé induced a clear hyperreactivity in most lesioned animals, but provoked initiation of mouse-killing behavior in only one-third. When produced in rats which had remained nonkillers following olfactory bulb removal, the raphé lesion clearly enhanced both the general and the emotional responsiveness; it provoked initiation of mouse-killing behavior in about 75% of the lesioned animals. The discussion bears on the correlations between interspecific aggressiveness and experimentally induced hyperreactivity in the rat.     

Physiological drives investigated by means of injections into the cerebral ventricles of the rat

A technique is described for permanently implanting a cannula in the lateral ventricle of the rat, and the effects on certain physiological drives of various substances injected by this route were investigated.

Food intake was significantly reduced by intraventricular glucose, while intra-ventricular fructose, insulin, glucagon and a lipid-mobilizing agent were without effect. Drinking was elicited by hypertonic saline and suppressed by hypotonic solutions. The intake of salt was not effected by intraventricular low-sodium solutions. Intraventricular procaine, but not alcohol, induced an akinetic state. Intraventricular glucose failed to relieve hypoglycaemic coma.

The significance of some of these findings is discussed in relation to the hypothalamic regulation of hunger.     

Rapid eye movement sleep deprivation affects sleep similarly in castrated and noncastrated rats

Twenty-four-hour recordings of electrophysiological correlates of the sleep-waking cycle in castrated and noncastrated Wistar rats were performed to validate the cuff pedestal technique in the deprivation of rapid eye movement sleep. An undisturbed pattern of sleep was found in both castrated and noncastrated rats when the cuffs were in the raised position. The lowering of the cuff for 4 days virtually abolished REMs in both groups of rats. During neither the dark nor the light period was there any difference between the castrated and noncastrated rats in the total amount of REMs rebound. The results accord with the data obtained by the conventional flowerpot procedure and show that castration does not influence the amount of REMs before, during, and after REMs deprivation in the rat. It is suggested that testicular testosterone, contrary to growth hormone, is not essential for the triggering of REMs sleep, although both have anabolic actions.     

预防性应用盐酸氟桂利嗪对高血糖SD大鼠局部脑缺血再灌注模型bcl-2表达的影响

探讨预防性应用盐酸氟桂利嗪对高血糖Sprague-Dawley(SD)大鼠局部脑缺血再灌注后bcl-2表达的影响,采用高血糖条件下SD大鼠局灶性脑缺血再灌注模型,36只雄性健康SD大鼠,建立高血糖模型后随机分为2组:高血糖组(n=18)、盐酸氟桂利嗪+高血糖组(简称氟桂利嗪组n=18),各组按脑缺血90min再灌注3h(n=6)、6h(n=6)、24h(n=6)分为3个亚组。应用免疫组织化学方法观察bcl-2的表达。结果氟桂利嗪组bcl-2于再灌注3h可见阳性表达,再灌注6h达高峰,至24h逐渐下降,各时间点之间比较差异显著,P0.01。氟桂利嗪组与高血糖组各再灌注时间点比较,缺血区bcl-2表达增加,差异显著,各时间点均为P0.01。证实预防性应用盐酸氟桂利嗪能使损伤脑区bcl-2表达上调,减轻高血糖条件下的局灶性脑缺血再灌注损伤。     

Desire for social contact,not empathy,may explain “rescue” behavior in rats

Ben-Ami Bartal et al. (Science 334:1427–1430, 2011) showed that a rat in an open space (free rat) would touch the front door of a restraining tube to open its rear door, thereby enabling a rat trapped within (trapped rat) to enter a larger space that was farther away from the free rat. Since opening the rear door distanced the trapped rat from the free rat, Ben-Ami Bartal et al. argued free-rat behavior could not be motivated by the pursuit of social contact. Instead, this rat was empathically motivated, its goal being to reduce the presumed distress of the rat trapped in the restraining tube. In two experiments, we show that (a) a free rat will not learn to touch the front door to open the rear door when it is the first condition of the experiment; (b) over time, a trapped rat will often return to a restraining tube despite its presumed aversiveness; and (c) a free rat experienced in touching the front door will continue to touch it even if touching does not free the trapped rat. We explain these results and Ben-Ami Bartal et al.’s in terms of two processes, neophobia and the pursuit of social contact. When first placed in a restraining tube, neophobia causes the trapped rat to escape the tube when the rear door is opened. Across sessions, neophobia diminishes, permitting the rats’ pursuit of social contact to emerge and dominate free- and trapped-rat behavior.