Conditioned-reflex facilitation in young and older adults

Young (18-30 years) and elderly (63-88 years) human subjects received 70 trials of single-cue classical eyeblink conditioning (paired group), or 70 explicitly unpaired presentations of the tone conditioned stimulus (CS) and airpuff unconditioned stimulus (unpaired group). Before and after conditioning, reflex-eliciting white noise and corneal airpuff stimuli were presented alone or paired with the CS to investigate the effects of conditioning on eyeblink reflex amplitude. The results showed increased conditioned responses in the paired group compared to the unpaired group for the young but not the elderly subjects. There was, however, evidence of conditioned facilitation of noise-elicited reflexes in both young and elderly subjects. These data indicate that conditioned facilitation of the startle reflex may be a sensitive indicator of classical conditioning processes in human subjects.     

Exposure to inescapable stress persistently facilitates associative and nonassociative learning in rats.

The present study examined the proactive effects of inescapable stress on aversive Pavlovian conditioning. Stressed rats were restrained and exposed to 90 1-mA tailshocks. Twenty-four hours later, all rats were exposed to 10 conditioned stimuli (CS; 350 ms of white noise at 85 dB). Rats then received either paired training in which the CS coterminated with a 100-ms, 0.7-mA periorbital shock or the same stimuli presented in an explicitly unpaired fashion. After the unpaired exposures, these rats were also exposed to paired training. Previously stressed rats exhibited persistent sensitization to the white-noise stimulus. Stressed rats exposed to unpaired stimuli, and no longer exhibiting a sensitized response, acquired the eyeblink conditioned response at a facilitated rate when these stimuli were presented in a paired fashion. These results also demonstrate that the effect of stress on classical conditioning is long-lasting, in excess of 48 hr. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tolerance to morphine in the rat: Associative and nonassociative effects.

Two experiments were conducted to examine the impact of dose level and interdose interval (IDI) on the development of tolerance to the analgesic effect of morphine. In Exp I, rats were administered a series of low- (5 mg/kg) or high- (30 mg/kg) dose injections of morphine either explicitly paired or unpaired with a distinctive context at a 48-hr IDI. The development of tolerance following this regimen was assessed by shifts in dose-response curves to the right when animals were tested on a tail-flick device in the distinctive context. Only animals that had received morphine paired with the distinctive context were tolerant to morphine; the magnitude of this associative tolerance was a positive function of the level of the conditioning dose. In Exp II, rats were exposed to a high dose of morphine (30 mg/kg) either paired or unpaired with a distinctive context at one of two IDIs (24 or 96 hr). Tolerance testing revealed that at the long IDI, only associative tolerance was evident, whereas at the short IDI, tolerance in the unpaired condition was more pronounced with a corresponding decline in the development of associative tolerance. The relevance of these findings for psychological theories of drug tolerance are discussed. Results are consistent with the predictions of an habituation model of drug tolerance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebellar stimulation as an unconditioned stimulus in classical conditioning.

Implanted rabbits with chronic stimulating electrodes in white matter underlying lobule HVI of the cerebellar cortex. Stimulation elicited movements of the face or neck and, when paired with a tone CS, produced learning comparable to that seen with peripheral unconditioned stimulus/stimuli (UCS). CS-alone trials produced extinction. Reinstatement of paired trials produced reacquisition with savings. Additional groups received either explicitly or randomly unpaired CS–UCS trials before paired conditioning. Low-frequency responding during these sessions indicated that the paired training results were associative and not due to pseudoconditioning or sensitization. Explicitly unpaired sessions retarded learning on subsequent paired trials compared with groups that received either randomly unpaired or no CS–UCS preexposure. These results are interpreted in terms of the role of the cerebellum and associated pathways in classical conditioning of motor responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What to do with significant multivariate effects in multivariate analyses of variance.

Significant multivariate tests in the multivariate analysis of variance are often followed by analyses of the contributions of individual dependent variables to those significant effects. There has been little agreement, however, as to which specific analyses should be performed. The use of the 2 most common techniques, analysis of variance for each dependent variable and discriminant analysis, are discussed and then illustrated in a computer study. It is suggested that the purpose of the user should determine the technique chosen as the 2 methods are not alternative approaches to the same problem. Analysis of variance can be used for hypothesis testing of individual variables and is appropriate for research. The value of discriminant analysis is in prediction and classification, although it can indicate complex relationships between measures in hypothesis testing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

连铸大方坯气瓶钢白点缺陷的防止

介绍电炉—大方坯连铸生产气瓶钢防止白点缺陷的改进措施。连铸大方坯轧制后的气瓶钢坯上经常发现轻微白点缺陷，在连铸中间包的开浇炉上更为明显。白点缺陷存在安全隐患，是气瓶钢中不允许存在的缺陷，为此加强对炼钢原辅材的防潮、VD真空过程以及中间包烘烤时间的管理，同时通过不同缓冷方式的试验，确定最合适的缓冷工艺，有效避免了轧制后钢坯白点现象的发生。在低倍组织检验时这种细小白点缺陷容易漏判，采用超声波探伤检查．对防止白点误判非常重要。     

1,25-Dihydroxyvitamin D3 receptors in the central nervous system of the rat embryo

The major aim was to identify predictors of the large age differences that exist in eyeblink classical conditioning. Eyeblink conditioning was assessed in 190 participants over the age range of 20-89 years, with 150 trained in the paired condition and 40 trained in the explicitly unpaired control condition. Timed-interval tapping was used to assess cerebellar function. Blink reaction time and explicit learning and memory were also assessed. Stepwise multiple regression indicated that the effect of age accounted for the largest proportion of the variance, but the cerebellar measure also predicted eyeblink conditioning at a significant level. Reaction time and explicit memory measures did not account for a significant amount of the variance in eyeblink conditioning. Age-related effects in the cerebellum apparently affect timing and learning in normal adults.     

Classical eyeblink conditioning in two strains of mice: Conditioned responses, sensitization, and spontaneous eyeblinks.

Conditioned eyeblink responses (CRs), sensitization, and spontaneous eyeblinks were studied in C57BL/6J and BALB/c mice. Both strains of mice acquired CRs during 10 days of classical delay eyeblink conditioning. The BALB/c mice reached a higher asymptotic CR level than the C57BL/6J mice. The CRs were extinguished and recovered in both strains following conditioned stimulus-alone and paired conditioned stimulus-unconditioned stimulus training. During 10 days of explicitly unpaired training, the control groups showed no signs of sensitization and low incidence of spontaneous eyeblinks. When switched to paired training, the unpaired groups exhibited significant conditioned inhibition. These results suggest that strain differences must be considered in experimental design and data interpretation for these basic aspects of associative learning and memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predictors of eyeblink classical conditioning over the adult age span.

The major aim was to identify predictors of the large age differences that exist in eyeblink classical conditioning. Eyeblink conditioning was assessed in 190 participants over the age range of 20–89 years, with 150 trained in the paired condition and 40 trained in the explicitly unpaired control condition. Timed-interval tapping was used to assess cerebellar function. Blink reaction time and explicit learning and memory were also assessed. Stepwise multiple regression indicated that the effect of age accounted for the largest proportion of the variance, but the cerebellar measure also predicted eyeblink conditioning at a significant level. Reaction time and explicit memory measures did not account for a significant amount of the variance in eyeblink conditioning. Age-related effects in the cerebellum apparently affect timing and learning in normal adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classical conditioning of proboscis extension in honeybees (Apis mellifera).

Conditioned extension of the proboscis in restrained honeybees with odor as the CS and sucrose solution—delivered to the antenna (to elicit extension of the proboscis) and then to the proboscis itself—as the UCS. In a 1st series of experiments, acquisition was found to be rapid, both in massed and in spaced trials; its associative basis was established by differential conditioning and by an explicitly unpaired control procedure. Both extinction and spontaneous recovery in massed trials were demonstrated. In experiments on the nature of the UCS, eliminating the proboscis component lowered the asymptotic level of performance, whereas eliminating the antennal component was without effect; reducing the concentration of sucrose from 20% to 7% slowed acquisition but did not lower the asymptotic level of performance; and second-order conditioning was demonstrated. In experiments on the role of the UCS, an omission contingency designed to eliminate adventitious response-reinforcer contiguity was found to have no adverse effect on acquisition. In experiments designed to analyze the resistance to acquisition found after explicitly unpaired training in the 1st experiments, no significant effect was found of prior exposure either to the CS alone or to the UCS alone, although the unpaired procedure again produced resistance that was shown to be due to inhibition rather than to inattention; extinction after paired training was found to be facilitated by unpaired presentations of the UCS. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebral amyloid angiopathy and plaques, and visceral amyloidosis in aged macaques

BACKGROUND: We wanted to verify whether the calculations of segmental tubular reabsorption obtained during water diuresis were supported by direct micropuncture measurements. METHODS: Experiments were performed on 18 rats during baseline water diuresis (B) and after the administration of frusemide (F), 10 mg/kg, by whole-kidney clearance measurements and micropuncture collections from early distal (ED) and last proximal (LP) tubular segments. RESULTS: GFR was 957+/-79 in B, 1053+/-77 microl/min in F, P>0.013. SNGFR was 38+/-1 in 166 and 38+/-1 nl/min in 165 tubules respectively, P>0.77. In LP collections the percentage reabsorption was 71+/-2 in B and 76+/-2% during F (P>0.07) in 99 and 95 samples respectively. The absolute proximal reabsorption was not changed by F (27.6+/-1.5 versus 27.7+/-1.3 nl/min, P>0.96) The data were superimposable when the analysis was restricted to paired data. The difference between ED and LP resorption was 17+/-3 during B and fell significantly (P<0.008) to 5+/-3% during F, measured by clearance techniques, and the percentage of GFR excreted during F, measured by clearance techniques, and the percentage delivery of filtrate beyond the proximal tubule, measured independently by micropuncture, were not different (27+/-2 versus 24+/-2%, P>0.10), while they were significantly correlated (P<0.04). The calculations of segmental Na reabsorption along the different nephron segments by clearance techniques were not significantly different from and were significantly correlated with the reabsorptions measured directly by micropuncture. CONCLUSIONS: The present experiments validate the calculations of reabsorption by techniques applicable to human studies of clinical physiology.     

Binomial variability in short-term memory.

Experiments in short-term memory usually collect binary data, e.g., an item is either correctly recalled or not. If the probability of recall is constant for Ss and/or items under a given condition, the proportion based on n observations can be transformed to angles by the arcsin transformation and will have variance 1/n. Violations of the assumptions are discussed and different strategies for pooling are assessed by conventional analysis of variance. Illustrative experiments with distractor and probe techniques, paired-associates and serial presentation, and single-trial free recall are briefly presented. The correspondence between observed and expected results seems good; apparently considerable latitude is possible in pooling Ss or items in data analyses of experiments in short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extracting summary statistics to perform meta-analyses of the published literature for survival endpoints

Meta-analyses aim to provide a full and comprehensive summary of related studies which have addressed a similar question. When the studies involve time to event (survival-type) data the most appropriate statistics to use are the log hazard ratio and its variance. However, these are not always explicitly presented for each study. In this paper a number of methods of extracting estimates of these statistics in a variety of situations are presented. Use of these methods should improve the efficiency and reliability of meta-analyses of the published literature with survival-type endpoints.     

Specific mismatch recognition in heteroduplex intermediates by p53 suggests a role in fidelity control of homologous recombination

We demonstrate that wild-type p53 inhibits homologous recombination. To analyze DNA substrate specificities in this process, we designed recombination experiments such that coinfection of simian virus 40 mutant pairs generated heteroduplexes with distinctly unpaired regions. DNA exchanges producing single C-T and A-G mismatches were inhibited four- to sixfold more effectively than DNA exchanges producing G-T and A-C single-base mispairings or unpaired regions of three base pairs comprising G-T/A-C mismatches. p53 bound specifically to three-stranded DNA substrates, mimicking early recombination intermediates. The KD values for the interactions of p53 with three-stranded substrates displaying differently paired and unpaired regions reflected the mismatch base specificities observed in recombination assays in a qualitative and quantitative manner. On the basis of these results, we would like to advance the hypothesis that p53, like classical mismatch repair factors, checks the fidelity of homologous recombination processes by specific mismatch recognition.     

Coding of spatial location information: An automatic process?

Several researchers have claimed that spatial location information is automatically encoded, a claim supported by studies testing several criteria for the identification of automatic processes. However, a careful look at these studies reveals that some have not used appropriate testing methodology, the results of others have not complied with the criteria, and some criteria have not been examined at all. This article includes four experiments in which five criteria for testing the automaticity of cognitive processes were examined. Results show that memory for spatial location information is influenced by intention, age of subjects, competing task loads, practice, strategy manipulations, and individual differences. These results generally hold for memory of absolute location and for relative location information. The reported results are at odds with the claim that memory for spatial location information is exclusively mediated by automatic encoding processes. The concept of automaticity and the appropriateness of the testing criteria are discussed in light of the current results and recent findings on other features of the environment claimed to be automatically encoded. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A weighted concordance correlation coefficient for repeated measurement designs

The need to quantify agreement between two raters or two methods of measuring a response often arises in research. Kappa statistics (unweighted and weighted) are appropriate when the data are nominal or ordinal, whereas the concordance correlation coefficient is more appropriate when the data are measured on a continuous scale. We develop weighted product-moment and concordance correlation coefficients which are applicable for repeated measurements study designs. We consider two distinct situations in which the repeated measurements are paired or unpaired over time. We illustrate the methodology with examples comparing (1) two assays for measuring serum cholesterol, (2) two estimates of dietary intake, from a food frequency questionnaire and dietary recalls, and (3) two measurements of percentage body fat, from skinfold calipers and dual energy x-ray absorptiometry.     

The "post-mortem" testing of experimental comparisons.

In an experimental design the investigator frequently wishes to go beyond an over-all analysis of variance F test, and seeks to examine specific means or totals from certain groups of treatments. In the a posteriori ("post-mortem") situation, where comparisons are suggested by examining the data, and have not been pre-planned, it is inappropriate to use the tabular F and t values, since these values are not based upon randomly selected observation. A procedure is recommended to handle this situation, one that avoids the danger of erroneous inferences (spuriously significant comparisons). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensory preconditioning in rats following early visual deprivation.

Conducted 3 experiments in which a total of 131 light- and dark-reared (LR and DR) male hooded rats were given sensory preconditioning (SPC). In each experiment, Ss were presented with 2 stimuli either paired or unpaired, followed by conditioning to 1 and extinction on the other. 2 auditory stimuli were used in Exp. I. SPC was found for both LR and DR Ss, with no significant difference due to rearing condition either in acquisition or in the SPC test. In Exp. II, light and tone were employed; SPC was demonstrated and was more effective for LR than DR Ss. In Exp. III, rectangle stimuli were employed. The effect of SPC was evidenced in LR Ss; however, performance of DR Ss was not significantly different from that of controls. Results are discussed in terms of the effect of early visual deprivation on information-processing mechanisms. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term chronoamperometric screening of chlorpromazine-package interactions

A new electroanalytical method has been developed to measure and predict solute sorption interactions with solid surfaces. By maximizing surface-to-volume ratios, this method significantly reduces the study time of drug-package interactions and allows prediction of possible long-term effects. Chronoamperometry experiments were run in 40 microL drops of solution containing drug placed on a solid substrate disk of about 7 mm diameter in a sample cell designed to accommodate a miniaturized three-electrode setup. Logarithmic current signatures obtained by computing Delta(ln i)/Delta(ln t) were used to define the experimental conditions necessary to avoid the kinetic complications of chlorpromazine oxidation in the interpretation of the results of the chronoamperometric analysis. Results of sorption studies of chlorpromazine to glass, polypropylene, high density polyethylene, poly(ethylene terephthalate), ethylene vinyl acetate, and poly(vinyl chloride) are presented. The small volume sorption experiments demonstrated that chlorpromazine interacts most quickly with PVC and HDPE and least with glass and polypropylene. Long term stability tests confirmed these predictions, thereby indicating that the small volume method makes drug-package interaction studies feasible in early development. The generation and analysis of Delta(ln i)/Delta(ln t) signature curves extends the usefulness of the electroanalytical method to other systems by accurately identifying the appropriate time domains for steady state or Cottrell behavior.     

Affective learning increases sensitivity to graded emotional faces.

How does the affective significance of emotional faces affect perceptual decisions? We manipulated affective significance by pairing 100% fearful faces with aversive electrical stimulation and hypothesized that increasing the significance of a stimulus via its prior history would lead to enhanced processing. After fear conditioning, participants viewed graded emotional faces that ranged from neutral to fearful. Faces were shown either in a color that was previously paired with shock or a color not paired with shock during conditioning. Increases in the frequency of "fearful" responses for faces shown in the shock-paired color were most robust for faces at intermediate intensity levels (40-60% fearful). Psychometric fits to the data revealed significant increased sensitivity for shock-paired relative to unpaired faces. Thus, despite identical physical features for shock-paired and unpaired stimuli (aside from the color, which was counterbalanced), more frequent (and faster) "fearful" responses were made when participants viewed affectively significant stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)