Memory facilitation by posttraining and pretest ACTH, epinephrine, and vasopressin administration: Two separate effects.

Rats were trained in a step-down inhibitory avoidance task using a 0.3-mA, 2-s, 60 Hz footshock and tested 24 hr later. The animals received, 1 min after training and/or 5 min before testing, an ip injection of saline, ACTH1–24 (0.2 μg/kg), lysine-vasopressin (10 μg/kg), epinephrine (5 μg/kg), naloxone (0.4 mg/kg), or a combination of naloxone with one of the hormones. Both the posttraining and the pretest injection of the hormones enhanced retention test performance; the enhancement was larger in animals that received the two treatments. Posttraining, but not pretest, naloxone administration also caused an enhancement. However, posttraining naloxone potentiated, and pretest naloxone antagonized, the effect of the concomitantly injected hormones. These data show that the posttraining and the pretest effect of the hormones are independent, are due to different mechanisms, and can be additive. In addition, it does not seem possible to explain posttraining memory facilitation by the hormones as owing to an addition to the reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned facilitation of brain reward function after repeated cocaine administration.

Cocaine lowers brain reward thresholds, reflecting increased brain reward function. The authors investigated whether, similar to acute cocaine administration, cocaine-predictive conditioned stimuli would lower intracranial self-stimulation (ICSS) thresholds. Rats received a saline injection for 5 days, a cocaine injection (10 mg/kg) for 20 consecutive days, then saline for 5 additional days. Thresholds were measured immediately before and 10 min after each injection. The initial 5 saline injections had no effect on thresholds, whereas cocaine significantly lowered thresholds for 20 days. There was no tolerance or sensitization to this effect of cocaine over days. During the last 5 days when cocaine administration was substituted with saline, rats demonstrated a conditioned lowering of thresholds during the 2nd daily ICSS session. These data demonstrate that cocaine-predictive conditioned stimuli induce a conditioned facilitation of brain reward function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory impairment in monkeys following lesions limited to the hippocampus.

Investigated the degree of memory impairment produced by a lesion limited to the hippocampus in 13 cynomolgus monkeys (Macaca fascicularis) with circumscribed hippocampal lesions who were tested on the delayed-nonmatching-to-sample task, a test of recognition memory that is sensitive to amnesia in humans. Ss were given no preoperative training and were given no postoperative experience prior to training on the task. A marked deficit was observed. The results, taken together with those from previous studies, also provide information about the role of factors that could potentially influence the level of memory impairment following hippocampal lesions. The level of impairment does not appear to be due to any of the following factors: time of testing after surgery, prior postoperative testing, surgical techniques, species differences, or behavioral training methods. However, preoperative training experience does appear to reduce the severity of the impairment, and this factor may account for the observation that the memory impairment associated with hippocampal lesions is sometimes mild. A recent case of human amnesia is discussed in which a bilateral lesion limited to a portion of the hippocampus produced a well-documented memory deficit. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extinction of facilitation.

Five experiments, with 80 female Carneaux pigeons, used an autoshaping preparation to explore the conditions that remove previously trained facilitation. Facilitation training consisted of arranging for a key light to be followed by grain only in the presence of a diffuse stimulus. The diffuse facilitator greatly enhanced pecking at this and other key lights. This enhancement was removed by several procedures that nonreinforced an excitatory stimulus during the facilitator, but enhancement was not eliminated when the facilitator was nonreinforced alone or together with a nonexcitatory key light. Furthermore, arranging for reinforcement to follow a key light both in the presence and absence of the facilitator did not reduce its power. Results are interpreted in terms of conditioned facilitation being the converse of some instances of conditioned inhibition. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory improvement following cardiac transplantation

Seventeen patients with severe cardiomyopathy underwent neuropsychological evaluation prior to and at least 1 year after successful heart transplantation. Study candidates were screened, and individuals with a history of stroke, cardiac arrest, or medical and neurological conditions which might affect brain function were excluded. Pre-transplant testing revealed normal intelligence and normal attentional, language, and executive abilities but impaired recent memory. Following heart transplant, memory functioning improved significantly, reaching normal levels. Other cognitive abilities remained unchanged. Results suggest that cardiomyopathy is associated with mesial temporal dysfunction, possibly attributable to inadequate or reduced cerebral blood flow and related hypometabolism. This cerebral dysfunction is potentially reversible following successful transplantation, which restores cardiac output and cerebrovascular perfusion.     

Memory distortion following exposure to false information in hypnosis.

92 Ss preselected for hypnotic responsiveness on the Harvard Group Scale of Hypnotic Susceptibility—Form A were tested in strict application of the real–simulating model of hypnosis to examine the hypothesis that hypnotic Ss distinctively incorporate false material into their memories when that material is introduced after, rather than before, hypnotic induction. Both real (n?=?46) and simulating (n?=?46) Ss were either exposed or not exposed to misleading information after receiving induction instruction. Procedures for testing were otherwise identical to those adopted in an earlier study by the 1st author and J. Tilden (see record 1984-14147-001) in which false information was presented prior to hypnosis. Results confirm the hypothesis and show that hypnotic Ss differed appreciably from simulating Ss by incorporating more misleading material into their memory. Findings highlight the possibility of distinctive processing in hypnosis and implicate lowered critical assessment by hypnotic Ss of information they confidently accepted in the hypnotic context. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cutaneous toxicity following the administration of dactinomycin

The author describes a patient who has a successful coronary artery bypass. Six weeks later, after a physical examination of the chest, she had unbearable sharp, stabbing pain around the incision which was not responding to nerve blocks, analgesics, nonsteroidal anti inflammatory agents, and epidural blocks. The pain was responsive to mexilitine and disappeared after three weeks of treatment.     

Increased baseline sway contributes to increased losses of balance in older people following triazolam

Flow limiting dissection may occur after rotational atherectomy and require urgent management. Important questions about the safety and effectiveness of bail-out stenting in this setting remain to be answered. We have observed that emergent stenting after rotational atherectomy can be accomplished successfully in most patients, high pressure stent dilatation is both necessary and well tolerated, and lesion debulking facilitates movement of stents into diseased arterial segments.     

Reduction of stimulus-bound food consumption in the rat following amphetamine administration.

Studied the effects of intraperitoneal administration of dextroamphetamine on stimulus-bound food consumption in 30 male sated rats. Lateral hypothalamic stimulation which resulted in feeding was either programed to occur at regular intervals or delivered by the S's response (self-stimulation). Stimulus-bound food intake was reduced by dextroamphetamine, 3.0 or 4.0 mg/kg dosages being sufficient to cause almost complete anorexia. Reflexive sniffing and chewing of food and self-stimulation behaviors were unaffected. Results indicate that amphetamine selectively interacts with the adrenergic feeding system of the lateral hypothalamus to produce an inhibition of food consumption. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

No evidence of hemispheric facilitation following the induction of negative and positive affect

A dichotomy is thought to exist between the hemispheres whereby the right hemisphere is specialized for the processing of negative emotions and the left hemisphere is specialized for positive emotions. Van Strien and Morpurgo (Neuropsychologia, 1992, 30, 845-848) demonstrated that the activation of negative and positive emotional states resulted in the allocation of attentional resources to the contralateral hemispace. In the present experiment we sought to replicate this effect and improve upon certain methodological features of the experiment. The effect of positive and negative emotions on performance in the left and right visual fields was investigated in 30 dextral students. Positive and negative emotional states were generated by presenting subjects with an emotive word prior to each trial and subsequently requiring them to use that word within a sentence. Performance within the left and right fields was measured using a gap detection task which was neutral in relation to functional asymmetry. No evidence of right or left visual field facilitation was found for the positive or negative conditions, respectively. These results are not interpreted as a refutation of hemispheric specialization for emotional valence. Instead, they are seen to highlight the frailty of hemispheric facilitation effects.     

Memory facilitation and stimulation of endogenous nerve growth factor synthesis by the acetylcholine releaser PG-9

This paper provides an overview of thermal injury resulting in death or hospitalization in New Zealand adults, defined as age 15 years and over. For the 10-year period 1978-1987, there were 493 adult thermal injury deaths resulting in an overall rate of 2.1 per 100000 person-years (95%CI: 1.9-2.3). For the year 1988, there were 644 hospitalizations resulting in a rate of 25.1 per 100000 (95%CI: 23.2-27.1). The highest rates of death and hospitalization were observed in the elderly (65 years of age and over). Young males (15-29 years) also had a very high rate of hospitalization. Residential fire was the most common type of burn event resulting in death (44%), and smoking materials were the most common source of ignition in fatal residential fires (37%). Hot liquids were the most common source of thermal energy for the hospitalized injuries (34%). Typical scenarios involved burns from hot water expelled from automobile radiators, from hot water use in the workplace, from hot beverages, and from household hot tap-water. The epidemiology of the adult thermal injuries in New Zealand is similar to that reported in other developed countries. Opportunities and strategies for the prevention of these injuries are discussed.     

The effects of triazolam on aggression in men.

To assess the effects of triazolam on human aggression, 46 male participants received either placebo or 0.25 mg triazolam using double-blind procedures. Approximately 60 min after drug ingestion, participants were given the opportunity to administer electric shocks to an increasingly provocative fictitious opponent during a competitive reaction time task. Aggression was defined as the level of shock the participant was willing to administer to the opponent. The results suggest that triazolam consumption was associated with increased levels of aggression. On average, participants who received triazolam set more intense levels of shock for the opponent, and selected the most extreme shock response available more frequently, than participants who received placebo. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dose effects of triazolam and scopolamine on metamemory.

The present study compared the acute dose effects of the benzodiazepine triazolam and the anticholinergic scopolamine on metamemory (knowledge and awareness of one’s own memory) in a two-phase paradigm designed to assess effects on both monitoring and control components of metamemory in both semantic (general knowledge) and episodic memory (cued-recall) tasks. Placebo and 2 doses each of triazolam (0.125, 0.25 mg/70 kg, oral) and scopolamine (0.25, 0.50 mg/70 kg, subcutaneous) were administered to 80 healthy volunteers (16 per group) in a double-blind, double-dummy, independent groups design. Both triazolam and scopolamine impaired episodic memory (quantity and accuracy) but not semantic memory. Results suggested that both drugs impaired monitoring as reflected in absolute accuracy measures (impaired calibration in the direction of overconfidence) and control sensitivity (the relationship between confidence and behavior). Overall, the results did not provide evidence for differences between triazolam and scopolamine in memory or metamemory. In addition to the clinical relevance of the observed effects, this study adds to the accumulating body of cognitive psychopharmacological research illustrating the usefulness of drug-induced amnesia as a vehicle to explore memory and metamemory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute abstinence effects following smoked cocaine administration in humans.

Acute abstinence symptomatology following multiple deliveries of smoked cocaine was examined. Twelve crack cocaine users (male and female) participated in an inpatient study. Participants smoked 7 deliveries of cocaine on each of 4 experimental days, with each participant being exposed twice to 2 dose sizes of cocaine (0.40 vs. 0.07 mg/kg "placebo"). Symptoms of cocaine abstinence were measured for 6 hr following cocaine administration and again the following morning. Participants reported feeling increased craving, anxiety, and uncertainty 30 min after the 7th delivery of 0.40 mg/kg cocaine, when cocaine plasma levels were still on the descending curve. It is not clear whether these were true abstinence effects or were due to residual effects of cocaine. No significant differences were found at subsequent abstinence-assessment points. These data indicate that acute abstinence effects from smoked cocaine in a laboratory setting may be minimal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory impairments following lesions to the mammillary region of the rat

The contribution of the mammillary region to learning and memory was investigated. It was demonstrated that lesions of this region impair performance on tasks that require memory for spatial information but that the deficit depends both on the amount of damage within the region and the difficulty of the task. A dissociation in the effect of such lesions on performance of comparable spatial and non-spatial memory tasks was shown. In contrast to the deficits observed on spatial memory tasks, the acquisition and retention of a complex non-spatial memory task was not impaired after extensive damage to the mammillary region. Such lesions also did not impair performance in a conditioned taste aversion task. These experiments suggest that the mammillary region may be selectively involved in spatial learning and memory.     

Increased expression of peripheral benzodiazepine receptors in the facial nucleus following motor neuron axotomy

Peripheral benzodiazepine receptors (PBRs) are expressed in a variety of tissues but are normally found at low levels in the brain. Following various types of nerve injury, a reactive gliosis results that exhibits a high expression of this receptor. To further characterize the expression of PBRs following neuronal injury, we evaluated PBR expression in the facial nucleus following facial nerve axotomy (FNA). Injury to a peripheral nerve results in a complex series of metabolic and morphological changes around the injured neuron. Transections of the facial nerve results in a rapid activation of both astrocytes and microglia around axotomized motor neurons. FNA resulted in an increase in the staining for both astrocytes (glial fibrillary acidic protein) and activated microglia (OX42). There was also a reduction in synaptic contacts with the motor nucleus as evidenced by reduced staining for the synaptic marker, synaptophysin. In sections labeled with [3H]-PK11195, the subsequent autoradiograms displayed marked increases in the labeling for PBRs. This increase was observed at 5, 7 and 10 days after nerve transection. The increase was primarily in the level of expression (Bmax), with no change in the affinity of the ligand (Kd). The increase in PBR expression after FNA supports the hypothesis that PBRs can be used as a sensitive marker for CNS injury.     

Effect of the problem space on subgoal facilitation.

Two experiments with a total of 116 undergraduates, using 2 versions of the missionary and cannibal problem, investigated the conditions under which the specification of a subgoal would facilitate problem solving. The specification of a subgoal significantly improved total performance only on the problem having the larger problem space. Specification of a subgoal in the smaller problem space significantly improved performance only in reaching the subgoal, and this occurred only when the subgoal was not too distant from the initial state. (PsycINFO Database Record (c) 2010 APA, all rights reserved)