Fifteen male mice from each of 4 inbred strains (C57BL/6J, BALB/cJ, CBA/J, and DBA/2J) were tested to determine their voluntary self-selection of a 10% solution of 1,2 propanediol (1,2 PD), A 3-carbon alcohol of low toxicity. As with ethanol, the C57BL/6J strain consumed significantly greater amounts that the 3 other low ethanol-selecting strains. A second experiment determined that the 3 low selecting strains suffered significantly greater depression of the central nervous system from 1,2 PD than the high selecting C57BL strain. It was also found that ethanol is a much more potent depressant that 1,2 PD. These results are discussed in terms of the possible role of neural sensitivity in regulating consumption levels of the 2 alcohols.
The salivary response in dogs was classically conditioned in 3 groups differing with respect to the number of acid reinforcements received. For 1 group, the US was paired with the CS on 100% of the trials; for the 2 other groups the US occurred on 25% and 50% of the trials, respectively. The principal findings were that: (a) the consistently reinforced Ss showed superior acquisition performance and faster extinction than partially reinforced Ss, (b) the distibution of drops during CS was essentially the same for all groups, and (c) a significant increase in the UR over acquisition training was observed for each group.
Confined 4 young male rhesus monkeys in vertical chambers for 6 wk. Ss' subsequent behavior over a 9-mo period in both a home-cage and playroom situation was compared with that of 4 controls housed individually or in pairs. In comparison to both control groups, chambered Ss exhibited excessive amounts of self-clasp and huddle behavior, abnormally low levels of locomotion and exploration, and an absence of social interaction with other monkeys. Implications for production and study of depressive behavior in monkeys are discussed. (26 ref.)
When shock was given in a circular runway, a single shock from a moving shock prod produced reliable prod avoidance and reliably decreased intertrial interval activity for 24 naive male albino rats. Also, a reliable positive correlation was obtained for avoidance scores and intertrial activity in these Ss. Ss shocked by the prod outside the runway were more active in the runway and had higher prod-avoidance scores than Ss shocked in the runway. Results indicate that fear may be conditioned in a single shock trial, and that fear produces reactions which vary with certain characteristics of the fear-eliciting stimulus: fearful situations produce immobility, while discrete approaching stimuli which elicit fear produce active avoidance. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Initially, any depressions in the rate of bar pressing of 1 rat during the pain responses of another adapted rapidly. When rats were given 6 1-sec. electric shocks, each following 30 sec. of shock to another rat, "Ss showed a dramatic depression in the rate of bar pressing to the pain response of another rat. This depression, considered a measure of anxiety, gradually extinguished, but it was still significantly present after 10 days." Unshocked control Ss did not show this depression. Control rats given shock, but unassociated with the pain responses of another, showed a lesser depression than that of the experimental group. From Psyc Abstracts 36:01:1EF32C.
10 rats with electrodes aimed at medial forebrain bundle-posterior hypothalamus (MFB), and 4 rats with electrodes aimed at septal area were trained to press for food for 1 hr/day. Food was available only during this session. After stable weight levels were demonstrated, rewarding brain stimulation was made available during the 1-hr feeding session. All septal Ss and 4 hypothalamic Ss maintained their weight on this regimen. The other 6 hypothalamic Ss essentially ignored food, spending most of the session self-stimulating, and "self-starved." Self-starving Ss had their electrodes extensively in MFB while surviving hypothalamic Ss had their electrodes in more lateral areas.
2 groups of 10 rabbits received classical, eyelid conditioning and extinction training. 1 group was given 220 acquisition trials and reinforced 100% of the time. A 2nd group was given 440 acquisition trials and reinforced 50% of the time. Partial reinforcement produced a decrement in acquisition performance, but no greater resistance to extinction than continuous reinforcement.
Virtually total depletion of cortical and hippocampal noradrenaline by stereotaxic injection of 6-hydroxydopamine into the fibers of the dorsal noradrenergic bundle produced no impairment in acquisition learning of a runway response for food reward. Extinction of this response, once learned, was markedly slower in the treated group than in controls, the treated animals perseverating in rapid running to the goal box even with no food present there. Similarly, no impairment was found on acquisition of a continuously reinforced lever-pressing response for food. Extinction of this response, however, was again slower in the treated group. Subsequent acquisition of a successive light-dark discrimination task was also slower in the treated group, with these animals perseverating in responding to the negative stimulus. Although selective forebrain noradrenaline loss does not impair the acquisition of appetitive responses, the suppression of responses in the absence of reward is impeded. A parallel is drawn with those effects found classically after surgical lesion to the hippocampus.
In Experiment 1, six age groups of rats were trained to run an alley for either partial (PRF) or continuous reinforcement (CRF). Training was during a 2-day period starting at six different ages, and extinction was initiated about 12 hr later. There was a clear partial reinforcement extinction effect (PREE) at all ages and, particularly after PRF training, an inverse relationship between resistance to extinction and age. In Experiment 2, retention and durability of persistence as well as immediate persistence were tested following acquisition at three different ages. The immediate extinction tests confirmed the results of Experiment 1. In the delayed extinction tests, greater resistance to extinction following PRF than following CRF was found in all age groups after both the retention and durability manipulations. In neither test was there an effect of age in original acquisition on the magnitude of adult persistence. These experiments confirm earlier findings of remarkable persistence in rats trained and tested at weanling age, show that the persistence is even greater in pre-weanlings, and show that it is retained into young adulthood.
CEREBRAL CORTEX PROJECTS IN A TOPOGRAPHICAL MANNER TO THE CAUDATE NUCLEUS. THE TAIL OF THE CAUDATE NUCLEUS RECEIVES FIBERS FROM THE INFEROTEMPORAL CORTEX; THE VENTROLATERAL PART OF THE HEAD OF THE CAUDATE NUCLEUS RECEIVES FIBERS FROM THE ORBITAL FRONTAL CORTEX; AND THE ANTERODORSAL PART OF THE HEAD OF THE CAUDATE NUCLEUS RECEIVES FIBERS FROM THE DORSOLATERAL FRONTAL CORTEX. IN THE MONKEY THESE SECTORS OF THE CAUDATE NUCLEUS SUBSERVE THE FUNCTIONS OF THE CORTEX FROM WHICH EACH RECEIVES PROJECTIONS, SUGGESTING THAT THE CAUDATE MAY BE EQUIPOTENTIAL WITH THE CEREBRAL CORTEX AND CAPABLE OF ASSUMING CORTICAL FUNCTIONS. IT ALSO SUGGESTS THAT THE STRIATUM IS THE 1ST LINK IN A MAJOR PATHWAY PROVIDING FOR CORTICAL REGULATION OF LOWER CENTERS. (28 REF.)
Presents a biography of Zing-Yang Kuo, who died in 1970. During his turbulent career he stood at the center of several important metatheoretical controversies and made unique investigative contributions to the study of behavior and the nervous system, particularly from the standpoint of developmental analysis. (46 ref.)
Injection of poison into rats after they drank in the presence of stimulus compounds of a drug state and a flavor resulted in little stimulus control by the drug state. In Experiment 1, half of the rats were poisoned after drinking salt water while stimulated with amphetamine and after drinking sugar water while sedated with pentobarbital, but they were not poisoned after salt-pentobarbital or sugar-amphetamine combinations. The other half were subjected to counterbalanced procedures. In abstract language, poisoning occurred after AX and BY stimulus combinations but did not occur after AY and BX combinations. In Experiment 2A, rats were poisoned only after consuming a particular flavored solution (salt or vinegar) in a particular state (pentobarbital or undrugged); that is, if AX was poisoned, BX, BY, and AY were experienced without poisoning. There was complete counterbalancing of flavors and drug states. Experiment 2B was similar except that amphetamine was used instead of pentobarbital. In both experiments, there was some discrimination learning based on the drug state, gut it was extremely weak.
Examined whether the delay, the spatial features, or a combination of the 2 is the critical factor giving rise to the delayed-alternation deficit produced by ablation of the principal sulcus in the monkey. 3 unoperated rhesus monkeys and 13 with fractional prefrontal lesions were compared on delayed response and place reversal, 2 tests which involve both factors, and go, no-go alternation, which involves only the delay factor. Results together with those from a previous study indicate that lesions of the dorsolateral prefrontal cortex produce 2 dissociable disorders, the 1 classically associated with the frontal lobes having its cortical focus in the principal sulcus, and the other, as yet poorly understood, with its focus in the arcuate sulcus. The classical disorder appears to be related to the combination of mnemonic and spatial factors rather than to either factor alone.
The copulatory performance of male rats, tested in a large seminaturalistic environment, was assessed to determine the relation between 22-kHz ultrasonic vocalizations and a range of sociosexual behaviors. The male rats were tested until sexual exhaustion. Such ultrasonic signals were shown to occur in a wider range of sociosexual circumstances than previously reported; for example, the calls occcurred in particular social circumstances during the preejaculatory period as well as during the postejaculatory interval. There was no consistent evidence that the emission of this call during the postejaculatory period consistently functions to keep the female away from the male. The nature and occurrence of postejaculatory ultrasonic signals showed increasing variability in successive ejaculatory series. The results of this and previous studies are interpreted within a semiotic theory of communication. The 22-kHz call is described as a message that makes available the information that the sender is in a socially depressed and withdrawn state.
Rats adjustment to 23-hr. food deprivation regime was measured by body weights, food and water intakes, 24-hr. revolving wheel activity, and activity during the last pre-feeding hour. Progressive changes in all measures continued for at least 15 days and pre-feeding activity was still increasing at 35 days.
After 23.5 hr. of deprivation rats received water for 30 min. When single deprivations were separated by recovery periods, the usual increases in consumption did not appear over drinking periods. When 2 complete adaptations to the drinking schedule were given, separated by a recovery period, the adaptation data were almost identical. It is concluded that rats drink more on successive days of a continuous deprivation schedule "because they need more water to serve their metabolic needs." (PsycINFO Database Record (c) 2006 APA, all rights reserved).
Effects of bilateral frontal lesions on locomotor activity were studied under various stimulus conditions. 8 monkeys were tested after, and 13 monkeys before and after, partial ablation of lateral frontal granular cortex or as unoperated controls. Ss with lesions that included sulcus principalis were hyperreactive to light. Their locomotor activity in light as well as darkness was more enhanced by relatively familiar auditory stimuli, and more depressed by relatively novel stimuli than that of unoperated Ss, or of Ss with lateral frontal lesions which spared sulcus principalis.
Studied the "clock" which in Norway rats, and many other organisms, measures time in units of 24 hr. and subunits of 12 hr. Under ordinary conditions, this device keeps time independently of all external and internal disturbances except light. To determine whether exposure to alternating periods of light and darkness of day and night plays any role in establishing this clock, tests were made on 20 rats blinded just after birth and on 6 congenitally blind rats. Both groups manifested this clock by alternating 12-hr phases of activity and inactivity. Results indicate that (a) the clock is inherent; (b) that it must have been built into the nervous system by a survival process in relation to alternating periods of light and darkness of day and night; and (c) that it must have originated in early evolutionary eras in the tropics where day and night have the same length, i.e., 12 hr.
Administered 0, 10, 25, or 40 trials in a shock-escape straight alley to 128 Swiss-Webster mice (Mus musculus) when 7 or 9 days old. All groups received an additional 25 training trials 24 hrs later. During original training, both age groups improved escape performance as a function of number of training trials. However, during retention testing, only the Ss trained when 9 days old displayed differences in performance due to amount of original training. Results support earlier research suggesting that the capacity for 24-hr retention of the escape response develops between 7 and 9 days of age in mice.
The isolated abdominal ganglion of the sea hare (Aplysia californica) contains an identifiable neuron which has a circadian rhythm in the frequency of its autorhythmic spikes. It was found that: (1) the phase of the rhythm has a seasonal modulation such that during the cool season the maximum spike rate occurs near the time of projected dawn or dusk while during the warm season the maximum spike rate occurs near the time of projected midday or midnight; (2) the cellular rhythm can be entrained to environmental light cycles having periods of 21, 24, or 27 hr.; (3) 27-hr light cycles reduce the cell's mean level of activity. (15 ref.)
The purpose of this study was to determine whether behavioral sparing would be demonstrated when septal lesions occurred prior to the age at which the tested behavior first appears in normal rats. Rats given septal lesions at 1 day or 7 days after birth performed at approximately chance on the Maier three-table task when tested at 90 days of age. Rats that had control electrode insertions at the same ages performed at a level similar to normal animals. Animals given septal lesions at either age explored significantly more than did control animals. Results are discussed in terms of the constancy over time of the septal contribution to performance on the three-table task and the involvement of the septum and hippocampus in the processing of spatial information.
In Exp I, 40 male Sprague-Dawley-derived rats subjected to apomorphine-induced malaise following a 2-min placement in a black compartment avoided this black compartment significantly more than 10 controls in a choice situation. The degree of aversion, however, was substantially reduced when Ss were provided water (or saccharin) in the black compartment during conditioning and testing. Ss learned to suppress consumption of fluid in the black compartment. In Exp II, 10 Ss were made ill in the black compartment. Later, when drinking saccharin (or saline) preceded placement in the black compartment, Ss learned to suppress consumption of that fluid. The black compartment had become a conditioned reinforcer for taste aversion. (19 ref.)
8 mongrel dogs were trained to press 2 panels on a Sidman avoidance schedule and then received Pavlovian fear conditioning in which CS1 signaled a shock USC. On some trials, CS2 occurred in place of shock. Returning to the avoidance task, CS2 was made contingent upon pressing 1 panel; a neutral CS followed presses on the other panel. Ss distributed their responses to produce CS2 more often than the neutral CS, but not increasing their overall response rate. This proves that CS2, a stimulus contrasted with shock, becomes a positive reinforcer.
EXPOSURE OF DOGS TO INESCAPABLE SHOCKS UNDER A VARIETY OF CONDITIONS RELIABLY INTERFERED WITH SUBSEQUENT INSTRUMENTAL ESCAPE-AVOIDANCE RESPONDING IN A NEW SITUATION. USE OF A HIGHER LEVEL OF SHOCK DURING INSTRUMENTAL AVOIDANCE TRAINING DID NOT ATTENUATE INTERFERENCE; THIS WAS TAKEN AS EVIDENCE AGAINST AN EXPLANATION BASED UPON ADAPTATION TO SHOCK. SS CURARIZED DURING THEIR EXPOSURE TO INESCAPABLE SHOCKS ALSO SHOWED PROACTIVE INTERFERENCE WITH ESCAPE-AVOIDANCE RESPONDING, INDICATING THAT INTERFERENCE IS NOT DUE TO ACQUISITION, DURING THE PERIOD OF EXPOSURE TO INESCAPABLE SHOCKS, OF INAPPROPRIATE, COMPETING INSTRUMENTAL RESPONSES. MAGNITUDE OF INTERFERENCE WAS FOUND TO DISSIPATE RAPIDLY IN TIME, LEAVING AN APPARENTLY NORMAL S AFTER ONLY 48 HR.
2 EXPERIMENTS ON DIFFERENCES BETWEEN STRAINS OF HOUSE MICE IN CHARACTERISTICS RELATED TO PROCESSES OF MEMORY TRACE FORMATION ARE REPORTED. IN EXP. I, PERFORMANCES ON ACTIVE SHOCK-ESCAPE AND PASSIVE SHOCK-AVOIDANCE TASKS WERE OBSERVED UNDER MASSED AND DISTRIBUTED PRACTICE CONDITIONS; ON BOTH TASKS STRAIN DBA/2J MICE WERE SUPERIOR WHEN LEARNING TRIALS WERE MASSED, WHILE STRAIN C57BL/6J MICE WERE SUPERIOR WHEN TRIALS WERE DISTRIBUTED. IN EXP. II, IMMEDIATE POSTTRIAL ETHERIZATION FACILITATED LEARNING OF BOTH TASKS FOR STRAIN DBA/2J MICE, BUT HAD NO EFFECT ON STRAIN C57BL/6J. (25 REF.) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Housed 300 dba/2j mice, genetically susceptible to audiogenic seizures, from weaning day 21 until testing day 26 either 1, 2, 3, 4, or 5/cage. Each s within each cage was then individually tested for its seizure response to intense acoustic stimulation. There were no effects on susceptibility to audiogenic seizures in an individual s as a result of immediate prior handling of its cagemates for testing. Increased crowding conditions led to a decrease in the average seizure response. This decrease was accounted for by finding that, on the average, only 1 s/cage manifested a full tonic seizure. Once a seizure onset occurred, the probability of the seizure terminating in the death of the s increased with more crowded conditions.
Male C57BL/6N (C57) and DBA/2N (DBA) inbred mice were found to differ in open-field behavior after an acute ip injection of ethanol and in the development of tolerance to repeated injections. DBA mice showed only increased activity for 28 min after ethanol doses up to 2.67% g/kg when compared with saline-injected controls. Under the same conditions, C57 mice showed dose-related increases in activity during the first 4 min, followed by dose-related decreases in activity. The effects endured for at least 60 min after injection in both strains. In a third experiment, mice were injected daily with saline or 2.0 g/kg ethanol and tested on Days 1, 5, 9, and 13 for open-field activity. On the 17th day, all mice were tested after an ethanol injection. Neither strain showed tolerance to the activity-stimulating effect of ethanol. Some evidence for tolerance to the effect of ethanol to reduce activity in C57 mice was found. In a fourth experiment, twice-daily injections of ethanol for 10 days produced marked tolerance to the depressant effect of an injection on the 11th day in C57 mice, compared with those in a control group given ethanol for the first time on the 11th day. No tolerance to the stimulant effect of ethanol was seen in C57s. DBA mice were injected twice daily for 19 days but did not display tolerance when tested on Day 10 or on Day 20, Indeed, DBA mice chronically treated with ethanol exhibited more marked stimulation of activity after ethanol than mice treated chronically with saline. Differences in blood ethanol concentrations between the strains could not account for any of the observed differences. Implications for the genetic control of responses to ethanol are discussed.
19 rats with electrodes implanted in lateral hypothalamus and other diencephalic, mesencephalic, and forebrain structures were tested for electrically evoked behavior and self-stimulation (SS). Some consummatory behaviors were selectively associated with SS. Locomotor exploration (LE), observed at 28 points, was the most consistently evoked behavior associated with SS. Significant positive correlations were found between maximum scores and thresholds of LE speed and SS rates. SS-LE points were located primarily in the medial forebrain bundle. The findings show that reinforcement is associated with excitation of neural mechanisms mediating approach sequences consisting of forward locomotion and consummatory reactions.
Chronic injections of high doses of progesterone (5 mg) and low doses of estradiol benzoate (EB; 2 microgram) resulted in less sexual behavior than did low doses of progesterone (.5 mg) and low doses of EB. In a typical procedure for inducing sexual behavior, EB and progesterone were given sequentially, separated by 42 hr. High levels of progesterone (2.5 and 5 mg) administered concurrently with EB inhibited the induction of sexual receptivity. Increasing the dose of EB from 2 microgram to 6 microgram or 10 microgram offset this inhibition. High doses of progesterone (5 mg) administered simultaneously or 2-16 hr prior to EB inhibited the induction of sexual behavior, but the inhibition waned when progesterone was administered 48 hr prior to EB. A single injection of progesterone (1 mg) that did not inhibit the induction of sexual behavior when administered concurrently with EB did inhibit lordosis when distributed into five injections (.2 mg) every 4 hr. The results of two experiments in which progesterone did not inhibit the uptake or retention of [3H]estradiol by brain cell nuclei suggest that the antiestrogenic action of progesterone in the central nervous system is not to interfere with the binding of estradiol.
The responses of monkeys with lesions of the frontal cortex and monkeys with lesions of the caudate nucleus were impaired (compared to unoperated controls) on alternation and delayed response tests presented in the Wisconsin General Test Apparatus, the deficit of the frontal monkeys being greater. From Psyc Abstracts 36:01:1DC00B. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Bilateral aspiration of the dorsal hippocampus produced a disrupttion of blocking of the rabbit's nictitating membrane response in Kamin's two-stage paradigm (Experiment 1) but had no effect on the formation of a Pavlovian conditioned inhibitor (Experiment 2). The results of Experiment 1 indicated that normal animals and those with cortical lesions given conditioning to a light-plus-tone conditioned stimulus (CS) gave conditioned responses (CRs) to both the light and the tone during nonreinforced presentations of each (test phase). If, however, compound conditioning was preceded by tone acquisition, only the tone elicited a CR during testing; that is, blocking was observed. In rabbits with hippocampal lesions, however, CRs were given to both the light and the tone during testing whether or not compound conditioning was preceded by tone acquisition. The data from Experiment 2 showed that rabbits with hippocampal lesions could discriminate as well as normal rabbits and those with cortical lesions between a light (CS+) and light plus tone (CS-). In addition, when the inhibitory tone was subsequently paired with the unconditioned stimulus in retardation testing, animals in all three lesion conditions acquired the CR at the same rate. Thus, it appears that hippocampal lesions do not disrupt conditioned inhibition. The results of these experiments were taken as support for the view that the hippocampus is responsible for "tuning out" stimuli that have no adaptive value to the organism.
SS MAINTAINED ON 23-HR FOOD DEPRIVATION CYCLES WERE HOUSED IN ACTIVITY WHEELS (EXPERIMENTAL) OR STANDARD LABORATORY CAGES (CONTROL). EXPERIMENTAL SS WERE UNABLE TO MAINTAIN BODY WEIGHT AND DIET; DESPITE HIGH LEVELS OF ACTIVITY, EXPERIMENTAL SS ATE SIGNIFICANTLY LESS THAN CONTROLS. INTERPOSING A 3-HR PERIOD BETWEEN RUNNING AND FEEDING, ADAPTING SS TO AREA OF FEEDING, OR ADMINISTERING PENTOBARBITAL (4 MG/KG) HAD LITTLE INFLUENCE ON THIS FOOD-INTAKE REDUCTION ("SELF-STARVATION"). CHLORPROMAZINE ADMINISTRATION (1 MG/KG) REDUCED ACTIVITY AND DID HAVE A SIGNIFICANT EFFECT ON SELF-STARVATION. HYPOTHALAMIC INVOLVEMENT IS DISCUSSED IN RELATION TO THERMO- AND GLUCOSTATIC THEORIES OF FEEDING AND A GENERAL EXCITABILITY FACTOR. (26 REF.)
Conducted 6 experiments with a total of 69 male Holtzman albino rats. The temporal functions relating inhibition and facilitation of the startle reaction, elicited by an intense auditory stimulus, to momentary and to prolonged acoustic and visual stimuli were studied. The extent of inhibition was positively related to the intensity of the stimulus in both modalities. The extent of facilitation was positively related to the intensity of the visual stimulus but nonmonotonically related to the intensity of the auditory stimulus, a relationship confirmed in a study of the effects of background noise level on startle behavior. Data are correlated with physiological processes which provide similar effects at the electrophysiological level. Some implications drawn for experiments on classical conditioning and habituation are discussed. (46 ref.)
In a study with 71 male Charles River rats, 20 out of 21 electrodes in the almost-exclusively noradrenergic cell concentrations of the locus coeruleus supported high and stable rates of self-stimulation. Locus coeruleus self-stimulation was facilitated by dextroamphetamine-sulphate and suppressed by chlorpromazine hydrochloride and a-methyl-p-tyrosine, but pimozide at relatively high doses had almost no effect. Results demonstrate that self-stimulation can be localized in a relatively homogeneous noradrenergic site and provide presumptive evidence that at least some noradrenergic neurons specifically mediate rewarding effects. (54 ref)
Grooming reflexes are induced by frontal neocortical, pontile, or spinal lesions in dogs and cats. In intact cats, the combined treatments of adrenalectomy and para-chlorophenylalanine administration induce grooming reflexes. Two other ways of depleting serotonin (with 5,7-dihydroxytryptamine and raphe lesions) were combined with adrenalectomy in the present study as further tests that serotonin and glucocorticoid hormones are the critical factors in the induction of grooming reflexes. Because the deficit in serotonin is confined to the superior colliculi in cats with frontal and pontile lesions, 5,7-dihydroxytryptamine (5,7-DHT) was injected directly into the superior colliculi at eight sites, 2 microgram/site (1 microliter at .5 microliter/min). Electrolytic dc lesions of the dorsal and superior central raphe nuclei were made in another group, and then both groups were adrenalectomized. There were three control groups: (a) a group with vehicle injections in the superior colliculi and laporatomies, (b) a group with 5,7-DHT injections in the superior colliculi, and (c) a group with the raphe lesions. Large receptive fields for grooming reflexes occurred only in the groups with combined treatments. Thus the mechanism of induction of grooming reflexes by central nervous system lesions involves independent changes in a hormonal and a neurotransmitter system which combine to effect the change in behavior.
Rats, like dogs, fail to escape following exposure to inescapable shock. This failure to escape does not dissipate in time; rats fail to escape 5 min, 1 hr., 4 hr., 24 hr., and 1 wk. after receiving inescapable shock. Rats that first learned to jump up to escape were not retarded later at bar pressing to escape following inescapable shock. Failure to escape can be broken up by forcibly exposing the rat to an escape contingency. Therefore, the effects of inescapable shock in the rat parallel learned helplessness effects in the dog.
A series of experiments assessed whether the ability of the antiestrogen CI-628 to inhibit estrogen-stimulated lordosis in adult ovariectomized rats depends upon its interference with the synergistic effects of estrogen with progesterone. In Experiment 1, the effect of CI-628 was contrasted in rats brought into estrus by a single subcutaneous injection of estradiol benzoate (EB) combined with an injection of progesterone (P) 42 hr later versus four daily injections of EB (without any P). CI-628 was given at the time of EB injection(s). CI-628 substantially and equally effectively antagonized lordotic responding in both conditions. In the absence of CI-628, rats receiving progesterone had significantly higher lordosis scores than the 4-day EB control animals. In Experiment 2, rats receiving CI-628 on only the first 2 of 4 days of EB injections had significantly decreased lordosis scores unless P was also given on the day of testing. This suggested that the EB from the latter injections was not acting as a progestin "mimic." In Experiment 3, lordotic responding stimulated by EB (without P) was inhibited by CI-628 in rats that were both ovariectomized and adrenalectomized. This suggested that adrenal progestins were not involved in the ability of CI-628 to inhibit lordosis. Taken together, the results suggest that the mechanism of action of CI-628 for the inhibition of lordosis does not depend upon its ability to antagonize an estrogen-induced increase in neural progestin receptors. Implications of this for estrogen-mediated behaviors, for which CI-628 has little or no antagonistic effects, are discussed.
Groups of mice were briefly exposed to a one-octave band of noise at 14, 18, 28, 38, or 58 days of age. Five days later the groups were divided, and some mice were behaviorally tested for audiogenic seizures by reexposing them to the same sound. The round window cochlear microphonic potential was measured in the remaining animals and compared with that observed in unprimed control subjects. Seizure behavior occurred in all animals primed on Day 18 but rarely for subjects in the other age groups. Cochlear microphonic threshold curves in mice primed on Day 18 showed a 30-dB loss in sensitivity, while all other primed groups showed little change. These data were discussed in terms of the "disuse-supersensitivity" hypothesis previously proposed to account for the physiological effects of priming in mice.
A cross-sectional design was used to study the development of acoustic startle behavior in C57BL/6J mice from the approximate onset of hearing (12 days) to 17 days of age. Startle incidence and latency were recorded in response to 5-, 7-, 10-, 15-, and 20-kHz tones each presented at 80, 90, and 100 dB (SPL). From 12 to 17 days of age, higher frequency and lower intensity tones became increasingly effective in eliciting the acoustic startle response. In addition, startle latency decreased substantially, and response incidence became more sensitive to changes in tone intensity and tone frequency. This rapid ontogeny of the acoustic startle response closely parallels previously demonstrated neurophysiological development of the mouse pup auditory system.
Mice of the C57BL/6J strain became hyperactive to increasing doses of morphine sulfate. This response was similar to locomotor hyperactivity induced by amphetamine. Lesions and chemical blockade of posterior n. accumbens abolished amphetamine-induced hyperactivity and reduced but did not abolish the morphine response. These experiments demonstrate that the response to the two drugs is mediated by overlapping but noncongruent neural systems.
It has been hypothesized that the emotionality of the female rat is reduced at estrus. In confirmation of previous research, it was found that administration of estradiol benzoate (EB;20 mug/kg) to female rats of the Maudsley Reactive (MR) strain increased open-field activity and decreased open-field defecation. In addition, ovariectomy increased open-field defecation in MR females. Supporting the generality of these findings, hormone administration reduced open-field defecation and increased open-field activity in intact females of a genetically heterogeneous background. Additional studies suggested that the decrease in open-field defecation at estrus is dependent on estrogenic suppression of food intake. Hormone replacement decreased food intake in the period preceding the open-field test, and colonic contents were also lower in rats treated with EB+P (progesterone) immediately after the completion of the open-field test. These changes were seen in both MR and genetically heterogeneous females. It was concluded that the decrease in open-field defecation at estrus may be mediated by a reduction in food intake and a consequent decrease in colonic contents and that the validity of the defecation response as a measure of emotionality may be seriously questioned under these circumstances.
Small colonies of rats were established, using adult animals that had either received continuous social experience or had been isolated since weaning. Unfamiliar "intruder" rats--with or without postweaning social experience--were exposed individually to the colonies for a 21-hr. period. Behavioral observations and an assessment of the intruder's physical condition indicated that serious fighting, physical injuries, and large weight losses occurred only when an isolation-reared intruder was placed into a colony of socially experienced rats. These results demonstrate that aggression is a joint function of the rearing history of both the colony and the intruder and that social experience plays an important role in the behavioral development of this species.
No neurological or behavioral effects of 62 hours exposure to the effects of primary cosmic radiation were noted in two Java monkeys, whose postexposure performances on behavioral tests were equal to or better than those of non-exposed controls.
The fluorescence intensity of the catecholamine cell bodies of the A2 group--as determined by microfluorimetry--increased significantly due to exposure of the rats to the following environmental events: placement of a rat from the colony cage into a cold (4 degree C) room for a period of 10 min, isolation of a rat from the colony for 6--7 days, and satiation of gouped rats by allowing them access to sweetened milk for 15 min. The following events failed to affect the intensity of the cells of A2: reduction of the group colony size from eight to three rats per colony for 6--7 days and presentation of water instead of milk after the rats had experienced 6--7 days of milk satiation. These results indicate that aversive as well as rewarding environmental events activate the catecholamine cells of A2.
The display of lordosis by an estrous female guinea pig in response to manual stimulation of the rump or in response to mounting by a male is terminated by the experience of coitus. Ss were 50 intact and 118 ovariectomized female guinea pigs. Without the experience of coitus, lordosis can be elicited repeatedly for 6-8 hr. when S is in either spontaneous or induced estrus. Mechanical stimulation of the vagina and/or cervix by a glass rod duplicates the abbreviating effects of coitus. Moreover, abbreviation of the receptive period by either coital or mechanical stimulation is independent of the ovary, of the amount of estrogen and progesterone used to induce lordosis, of the pituitary, and of the amoung of pituitary hormone injected during estrus. Results suggest that the inhibitory effects of vagino-cervical stimulation are neurally mediated and hormonal mechanisms are not necessary for the influence of the sensory experience. (36 ref.)
The role of the pelvic nerves in the postmating abbreviation of behavioral estrus in domestic female rats was investigated. Mating during a period of 40 min at the beginning of hormonally induced estrus in spayed female rats resulted in a rapid decrease in receptivity as measured hourly by the lordosis response. Moreover, the length of the receptive period was significantly shortened by mating at the start of the period. Bilateral pelvic nerve transection completely abolished these effects of mating. Continuous exposure to sexually active males throughout the period of receptivity resulted in a more pronounced decline in receptivity but again was without effect in pelvectomized females. Apparently genital stimuli mediated by the pelvic nerves are responsible for the postcopulatory decrease in receptive behavior in the female rat.
Rats with complete subdiaphragmatic bilateral transection of the abdominal vagus (Vgx-C) showed disordered food-related drinking when drinking water in temporal association with a meal of dry food after 5-hr food deprivation and when drinking water in association with a liquid meal after 24-hr food deprivation. The Vgx-C rats drank after significantly longer latencies and drank significantly less water in 1 hr than did sham-vagotomized (Sham) rats after eating the same size meal (solid or liquid) as Shams. Rats with incomplete vagal transection (Vgx-I) ate and drank like Shams. Water intake of Sham and Vgx-I rats correlated positively with the meal size of solid food, but the water intake of Vgx-C rats did not. The failure of Vgx-C rats to drink water normally when food was ingested was not due to failure of a food stimulus to reach the intestine, because Vgx-C and Sham rats emptied equivalent volumes of liquid food from the stomach into the intestine within 10 min of food entering the stomach. These results indicate that the abdominal vagus is an important neurological substrate for food-related drinking in the rat.