Effect of electroconvulsive shock on an extinguished "fear" response

To test Gellhorn's hypothesis that electroconvulsive shock reinstates extinguished responses, a conditioned "anxiety" response was established and then extinguished in rats. A series of treatments did not restore the extinguished "anxiety" response; in fact, control animals showed appreciable spontaneous recovery of the "anxiety" response while treated animals did not.     

Behavioral method for study of pain in the monkey

A behavioral method is described in which increasing intensities of electric shocks were applied to the gasserian ganglia of alert monkeys. The animals were trained to press a lever to regulate the shock level. "Pain thresholds" were thereby obtained, and these thresholds were modified by varying the shock duration and by administration of morphine.     

Infant handling: effects on avoidance learning, brain weight, and cholinesterase activity

Infant rats were "handled" by removing them periodically from their home cages. "Non-handled" rats were left undisturbed. Half of the animals were killed at weaning, and weights and cholinesterase activity were determined on four different sections of the brain. The remaining animals were conditioned to avoid an administered shock. Handling increased ventral-cortex and subcortical weights and decreased subcortical cholinesterase. No differences in avoidance conditioning were observed.     

Recovery from retrograde amnesia: a learning process

Retrograde amnesia was produced in rats by electroconvulsive shock. Memory recovered if the animals were given repeated test trials. Memory did not recover if steps were taken to reduce the conditioning properties of the test trials; the manipulations included eliminating the response, altering the apparatus cues, or extinguishing conditioned "fear" by confining animals to the apparatus during the first test trial.     

Retrograde amnesia produced by electroconvulsive shock after reactivation of a consolidated memory trace

Rats had a memory loss of a fear response when they received an electroconvulsive shock 24 hours after the fear-conditioning trial and preceded by a brief presentation of the conditioned stimulus. No such loss occurred when the conditioned stimulus was not presented. The memory loss in animals given electroconvulsive shock 24 hours after conditioning was, furthermore, as great as that displayed in animals given electroconvulsive shock immediately after conditioning. This result throws doubt on the assertion that electroconvulsive shock exerts a selective amnesic effect on recently acquired memories and thus that electroconvulsive shock produces amnesia solely through interference with memory trace consolidation.     

Theta rhythm: a temporal correlate of memory storage processes in the rat

We examined the amount of theta rhythm (4 to 9 hertz) in cortical electroencephalograms of rats for 30 minutes after training in one-trial tasks. Some animals received electroconvulsive shock after training. The amount of theta in the electroencephalogram after training was positively correlated with the degree of subsequent retention of a footshock, whether animals had received electroconvulsive shock or not.     

Retrograde amnesia: electroconvulsive shock effects after termination of rapid eye movement sleep deprivation

Mice that were deprived of rapid eye movement sleep for 2 days immediately after one-trial training in an inhibitory avoidance task and were given an electroconvulsive shock after deprivation displayed retrograde amnesia on a retention test given 24 hours later. Electroconvulsive shock produced no amnesia in comparable groups of animals that were not deprived of rapid eye movement sleep.     

热激处理对番茄幼苗抗冷性的影响

试验以"月光"番茄为试材,研究了热激处理对番茄幼苗抗冷性的影响。结果表明,番茄幼苗经过44℃、2h的热激处理后其抗冷性明显增加。热激处理提高了番茄幼苗叶片内的可溶性蛋白质含量,使幼苗在经低温伤害后其可溶性蛋白质含量仍保持一个较高的水平。经过热激处理的幼苗在经受低温伤害时其相对电导率和丙二醛含量显著低于对照。     

Paradoxical fear-increasing effects of tranquilizers: evidence of repression of memory in the rat

Conditioned suppression of feeding, an index of fear, was increased rather than decreased by the administration of benzodiazepine tranquilizers or amobarbital. The drug-induced increase in conditioned fear varied directly with the intensity of the shock used in fear conditioning. The drugs had no fear-increasing effect in unshocked controls or in rats made amnesic by electroconvulsive shock given immediately after fear conditioning. These observations in animals are reminiscent of clinical reports that intraveneous amobarbital facilitates the recall of repressed traumatic experiences. The retrieval of painful memories may be inhibited or repressed in animals as well as in humans. In both cases, tranquilizers may counteract repression by disinhibition of the act of retrieval.     

Reinforcement magnitude as a determinant of performance decrement after electroconvulsive shock

The intensity of a foot shock may be a determinant of the rate at which an avoidance response becomes resistant to disruption by electroconvulsive shock. Mice were trained, one trial a day, in a passive avoidance learning task, with one of three foot-shock intensities. Electroconvulsive shock was administered at various intervals after each trial. At all foot-shock intensities, electroconvulsive shock given 10 seconds after each training trial was eflective in disrupting learning. Where electroconvulsive shock was given at longer intervals after each trial, those animals learning at low intensities of foot shock showed greater impairment of performance than those learning at high intensities.     

Puromycin and retention in the goldfish

A first experiment compared the behavior of goldfish injected with puromycin immediately after each of a weekly series of brief discriminative training sessions in the shuttlebox to that of appropriate controls. Discrimination was not prevented, nor was escape from shock impaired, but probability of response to the conditioned stimuli, both positive and negative, was reduced substantially. These results suggest that puromycin interferes with the consolidation of conditioned fear. The null outcome of a second experiment, in which all training was given in a single long session instead of a series of short sessions, suggests (contrary to recent indications) that consolidation begins in the training session. The conditioned-fear hypothesis is supported by the results of a third experiment in which the animals were shocked upon entering a goalbox to which they had previously learned to swim for food; animals injected with puromycin, immediately after the shock, entered the goalbox more readily 1 week later than did appropriate controls.     

Retrograde amnesia: production of skseletal but not cardiac response gradient by electroconvulsive shock

Rats given a single electroconvulsive shock immediately after but not 60 seconds after an aversive conditioning trial exhibited behavioral retention deficits 24 hours later in a one-trial passive avoidance task. In contrast to these differential performance deficits, similar heart-rate changes, indicative of fear retention, were seen in punished animals irrespective of the time of delivery of the shock. These data suggest retention of a generalized fear to the training experience that was not revealed by the behavioral measure. The potential usefulness of concomitant behavioral and physiological response assessment in consolidation research is discussed.     

Sleep: changes in threshold to electroconvulsive shock in rats after deprivation of "paradoxical" phase

Rats were deprived of paradoxical (radid eye movement or REM) sleep for a 6-day period but were allowed substantial non-REM (slow wave) sleep. Thresholds for electroconvulsive shock dropped significantly after deprivation in all these animals, but thresholds in control animals treated in a similar manner, but allowed REM sleep exhibited no change. Deprivation seems to heighten neural excitability.     

Tissue levels of norepinephrine and epinephrine in hemorrhagic shock

Severe depletion of endogenous norepinephrine was observed in the brain, heart, liver, and spleen of albino rabbits in which hemorrhagic shock had been induced. On the other hand, the epinephrine content of these tissues was significantly elevated above the levels in tissues of control animals. The norepinephrine and epinephrine levels of skeletal muscle in shocked animals remained unaffected.     

Interanimal "memory" transfer: results from brain and liver homogenates

Sixty mice received either shock or no shock in a shuttle box, or nonspecific stress in another apparatus. Brain and liver homogenates from these animals were then injected into 120 naive recipients, who were all tested in the shuttle box. Subjects receiving brain or liver from shocked or stressed donors had significantly higher latencies than control counterparts. These results are interpreted in terms of stress, rather than a memory transfer hypothesis.     

Ether-induced retrograde amnesia for one-trial conditioning in mice

Mice were tested in a situation permitting them to step readily from a small, restrictive platform to a larger one. Conditioned avoidance was established by a single training trial when animals received a shock by stepping from one platform to another. At various intervals after the single punishing shock, subjects were anesthetized with diethyl ether. Interference with retention, tested 1 day later, was shown for intervals up to 24 minutes, at which time ether no longer appeared to influence the subsequent response.     

Earth's Bow Shock: Elapsed-Time Observations by Two Closely Spaced Satellites

Coordinated observations of the earth's bow shock were made as Vela 3A and Explorer 33 passed within 6 earth radii of each other. Elapsed time measurements of shock motion give directly determined velocities in the range 1 to 10 kilometers per second and establish the existence of two regions, one of large amplitude magnetic "shock" oscillations and another of smaller, sunward, upstream oscillations. Each region is as thick as 1 earth radius, or more.     

Classical conditioning of pain-elicited aggression

Unconditioned aggression between paired animals in response to electric shock has been previously demonstrated. In this study, with the use of classical Pavlovian conditioning procedures, aggression was produced between paired rats as a response to a tone stimulus.     

Relationship of stress-induced histidine decarboxylase to circulatory homeostasis and shock

Histidine decarboxylase activity of mouse tissues is increased by stress and by injection of epinephrine and norepinephrine, suggesting a balance between histamine and catechol amines producing a component of circulatory homeostasis. Imbalance during intense stress might lead to failure of circulatory homeostasis and to shock. Reasons for discounting histamine as "shock toxin" may be invalid.     

Distinct "feeding" and "hunger motivating" systems in the lateral hypothalamus of the rat

Electrodes were implanted in the middle hypothalamus of rats to determine the neural organization of the "feeding" centers. Stimulations of the farand midlateral hypothalamic area produced feeding responses in sated animals, but only the former caused sated animals to cross an electrified grill to press a lever for food. After lesions had been made in the medial forebrain bundle, however, stimulations in the far-lateral hypothalamic area resulted in feeding in sated animals but failure to cross the electrical barrier to press a lever for food. Simultaneous far-lateral and "satiety" center stimulations produced feeding in sated animals but failed to "motivate" grill-crossing behavior.