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The present study focuses on the role of frequency bias and expected value on the learning processes driving performance on the Iowa Gambling Task (IGT) in individuals between 5 and 89 years of age. As in previous studies, children performed poorly on the IGT, were increasingly influenced by frequency of losses during learning, and constantly changed their decisions. Decision-making strategies changed after childhood from erratic behavior to more consistent strategies that promoted expected value of deck choices. Performance deficits as well as a loss frequency bias were found in older adults. However, age-related deficits were distinct between children and older adults. Cognitive modeling analysis indicated that older adults were more likely to forget about recent outcomes and were more consistent than children when selecting decks. Cognitive ability was associated with a modeling parameter for memory as well as IGT performance, suggesting the involvement of a cognitive component in young and middle-aged adult decision making. The interactions of modeling parameters suggested that cognitive changes were the cause of lowered performance in older adults. These analyses suggest critical developments in decision processes during the adolescent years and decline in a cognitive process leading to decision-making deficits after age 60., (PsycINFO Database Record (c) 2014 APA, all rights reserved.)

Objectives: To investigate the concurrent validity of the Saint Louis University Mental Status examination (SLUMS) by comparing the ability of the Mini-Mental State Examination (MMSE) and the SLUMS to predict performance on standard neuropsychological measures of memory and executive functioning., Design: Cross-sectional., Setting: University-based research clinic., Participants: Community-dwelling adults (N = 170) age 60 years and older (Mage = 73.08; SD = 8.18)., Measurements: The Trail Making Test (TMT), Rey Auditory Verbal Learning Test, Wisconsin Card Sorting Test (WCST), MMSE, and SLUMS., Results: The distributional properties of the SLUMS and the MMSE were directly compared. The SLUMS showed statistically a smaller mean, lower rank scores, and less skewness than the MMSE. Comparisons of the correlations of the screening tests with the neuropsychological measures indicated that the SLUMS demonstrated stronger relationships with the TMT compared with the MMSE. Multiple regression analyses were conducted to determine the ability of the SLUMS and the MMSE to predict scores on common neuropsychological tests after controlling for demographic variables. Results demonstrated that the SLUMS significantly predicted performance across all measures over the MMSE and demographic variables, with the exception of the WCST's perseverative errors. However, the MMSE does not add to the prediction of neuropsychological functioning over the SLUMS., Conclusion: Although the SLUMS and the MMSE are strongly correlated, the SLUMS significantly adds to the prediction of neuropsychological measures beyond the MMSE scores. Our findings suggest that the SLUMS may be an appropriate measure to use as a screening tool among older adults and may have fewer ceiling effects than the MMSE., (Copyright © 2013 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.)

Air-water interfaces interact strongly with colloidal particles by capillary forces. The magnitude of the interaction force depends on, among other things, the particle shape. Here, we investigate the effects of particle shape on colloid detachment by a moving air-water interface. We used hydrophilic polystyrene colloids with four different shapes (spheres, barrels, rods, and oblong disks), but otherwise identical surface properties. The nonspherical shapes were created by stretching spherical microspheres on a film of polyvinyl alcohol (PVA). The colloids were then deposited onto the inner surface of a glass channel. An air bubble was introduced into the channel and passed through, thereby generating a receding followed by an advancing air-water interface. The detachment of colloids by the air-water interfaces was visualized with a confocal microscope, quantified by image analysis, and analyzed statistically to determine significant differences. For all colloid shapes, the advancing air-water interface caused pronounced colloid detachment (>63%), whereas the receding interface was ineffective in colloid detachment (<1.5%). Among the different colloid shapes, the barrels were most readily removed (94%) by the advancing interface, followed by the spheres and oblong disks (80%) and the rods (63%). Colloid detachment was significantly affected by colloid shape. The presence of an edge, as it occurs in a barrel-shaped colloid, promoted colloid detachment because the air-water interface is being pinned at the edge of the colloid. This suggests that the magnitude of colloid mobilization and transport in porous media is underestimated for edged particles and overestimated for rodlike particles when a sphere is used as a model colloid.

Older adults have been shown to exhibit a positivity effect in processing of emotional stimuli, seemingly focusing more on positive than negative information. Whether this reflects purposeful changes or an unintended side effect of declining cognitive abilities is unclear. For the present study, older adults displaying a wide range of cognitive abilities completed measures of attention, visual, and verbal memory; executive functioning and processing speed; as well as a socioemotional measure of time perspective. Regression analyses examined the ability of these variables to predict neural responsivity to select emotional stimuli as measured with the late positive potential (LPP), an event-related brain potential (ERP). Stronger cognitive functioning was associated with higher LPP amplitude in response to negative images (i.e., greater processing). This does not support a voluntary avoidance of negative information processing in older adults for this particular measure of attentional allocation. A model is proposed to reconcile this finding with the extant literature that has demonstrated positivity effects in measures of later, controlled attentional allocation.

Temporal processing, or processing time-related information, appears to play a significant role in a variety of vital psychological functions. One of the main confounds to assessing the neural underpinnings and cognitive correlates of temporal processing is that behavioral measures of timing are generally confounded by other supporting cognitive processes, such as attention. Further, much theorizing in this field has relied on findings from clinical populations (e.g., individuals with schizophrenia) known to have temporal processing deficits. In this study, we attempted to avoid these difficulties by comparing temporal processing assessed by a pre-attentive event-related brain potential (ERP) waveform, the mismatch negativity (MMN) elicited by time-based stimulus features, to a number of cognitive functions within a non-clinical sample. We studied healthy older adults (without dementia), as this population inherently ensures more prominent variability in cognitive function than a younger adult sample, allowing for the detection of significant relationships between variables. Using hierarchical regression analyses, we found that verbal memory and executive functions (i.e., planning and conditional inhibition, but not set-shifting) uniquely predicted variance in temporal processing beyond that predicted by the demographic variables of age, gender, and hearing loss. These findings are consistent with a frontotemporal model of MMN waveform generation in response to changes in the temporal features of auditory stimuli., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Unlabelled: BACKGROUND/STUDY CONTEXT: Previous tests of the relationship between subjective organization during encoding, aging, and recall have produced inconsistent findings. The present study investigates subjective organization and the acquisition and recall of verbal material across the life span (from 5 to 89 years of age) using two measures, the intertrial repetition paired frequency (PF) measure and the unidirectional subjective organization (SO) measure., Methods: Participants (N = 2656) were administered a version of the Rey Auditory Verbal Learning Test, including a delayed recall trial. Analyses of variance (ANOVAs) were performed to examine the relationship between age and subjective organization and between age and recall. Mediation and growth curve analyses were performed to further examine the relationship between age, verbal acquisition, and subjective organization., Results: Subjective organization was not predictive of verbal forgetting. Deficits in verbal acquisition and subjective organization were detected among children and elderly adults. Mediational analyses showed that age affected the number of words recalled as well as subjective organization, and that subjective organization affected the number of words recalled in children, young adults and elderly. Latent growth curve modeling suggests that increases in subjective organization over time are related to increases in recall over time for each age group., Conclusion: Subjective organization is predictive of recall, and both subjective organization and recall are lowest among children and elderly individuals. Age has direct effects on recall but this effect is partially mediated by subjective organization. Brain imaging studies showing increased prefrontal cortex activation during encoding of remembered words bolster our findings that age affects the relationship between verbal learning and organization of material during encoding.

The present study aimed to investigate changes in facial expression recognition across the lifespan, as well as to determine the influence of fluid intelligence, processing speed, and memory on this ability. Peak performance in the ability to identify facial affect was found to occur in middle-age, with the children and older adults performing the poorest. Specifically, older adults were impaired in their ability to identify fear, sadness, and happiness, but had preserved recognition of anger, disgust, and surprise. Analyses investigating the influence of cognition on emotion recognition demonstrated that cognitive abilities contribute to performance, especially for participants over age 45. However, the cognitive functions did not fully account for the older adults' impairments on expression recognition. Overall, the age-related deficits in facial expression recognition have implications for older adults' use of non-verbal communicative information.

In previous research, older adults responded to mortality salience (MS) with increased tolerance, whereas younger persons responded with increased punitiveness. One possible explanation for this is that many older adults adapt to challenges of later life, such as the prospect of mortality, by becoming more flexible. Recent studies suggest that positively oriented adaptation is more likely for older adults with high levels of executive functioning. Thus, we hypothesized that the better an older adult's executive functioning, the more likely MS would result in increased tolerance. Older and younger adults were randomly assigned to MS or control conditions, and then evaluated moral transgressors. As in previous research, younger adults were more punitive after reminders of mortality; executive functioning did not affect their responses. Among older adults, high functioning individuals responded to MS with increased tolerance rather than intolerance, whereas those low in functioning became more punitive.

Unlabelled: BACKGROUND/STUDY CONTEXT: An emotion recognition task that morphs emotional facial expressions from an initial neutral expression to distinct increments of the full emotional expression was administered to 482 individuals, 20 to 89 years of age., Methods: Participants assessed six basic emotions at 25%, 50%, 75%, and 100% of the full facial expression., Results: Participants in the three oldest age groups (60s, 70s, and 80s) demonstrated decreased performance for the recognition of the fear, anger, and sad emotions. Increased age was associated with increased recognition rates for the disgust expression, whereas no age effect was detected for the happy and surprise expressions. Covariate analyses revealed age effects were reduced by processing speed, but were unaffected by decision-making ability. The effects of age on individual emotions and levels of presentation are discussed., Conclusion: These findings suggest that age has the greatest impact on the recognition of the sad emotion and the greatest age effect at the 50% level of presentation across the adult life span.

The ability to generate specific genetic mutations in mice is a powerful tool to study normal and pathophysiological function. In order to determine the effects of a mutation, measurement of physiological variables, such as biopotentials, is often necessary. However, such measurements can be particularly challenging to obtain from an awake, unrestrained mouse. The goal of this study was to design and implement a telemetry system suitable for recording biopotentials from a mouse. A battery-powered system was fabricated from commercially available electronic components mounted on a small circuit board. The frequency response of the system was measured over a range of frequencies and found suitable for recording biopotentials in mice and larger animals. We affixed the circuit board externally to a mouse and connected surface electrodes to measure electrocardiograms (ECG). The size and weight of the board did not disturb normal behavior over 30-60 min. Recorded ECGs had easily identifiable components relevant to physiological parameters and had a similar frequency spectrum compared to recordings obtained from a commercially available measurement system. In conclusion, the telemetry system was low-cost due to the availability of the components, straightforward to implement, and provided biopotential recordings suitable for measuring physiological parameters in an awake mouse.

Latent growth models were applied to data on multitrial verbal and spatial learning tasks from two independent studies. Although significant individual differences in both initial level of performance and subsequent learning were found in both tasks, age differences were found only in mean initial level, and not in mean learning. In neither task was fluid or crystallized intelligence associated with learning. Although there were moderate correlations among the level parameters across the verbal and spatial tasks, the learning parameters were not significantly correlated with one another across task modalities. These results are inconsistent with the existence of a general (e.g., material-independent) learning ability.

This study examined the contributions of general slowing and task-specific deficits to age-related changes in Stroop interference. Nine hundred thirty-eight participants aged 20 to 89 years completed an abbreviated Stroop color-naming task and a subset of 281 participants also completed card-sorting, simple reaction time, and choice reaction time tasks. Age-related increases in incongruent color-naming latency and card-sorting perseverative errors were observed. Hierarchical regression analyses showed that the processing speed measures accounted for significant variance on both dependent measures, but that there was also a significant residual effect of age. An additional regression analysis showed that some of the variance in incongruent color-naming, after controlling for processing speed, was shared with the variance in perseverative errors. Overall, findings suggest that the age difference in Stroop interference is partially attributable to general slowing, but is also attributable to age-related changes in task-specific processes such as inhibitory control.

Sexual reproduction strategies vary both between and within species in the level of investment in offspring. Life-history theories suggest that the rate of sexual maturation is critically linked to reproductive strategy, with high investment being associated with few offspring and delayed maturation. For humans, age of puberty and age of first sex are two developmental milestones that have been associated with reproductive strategies. Stress during early development can retard or accelerate sexual maturation and reproduction. Early age of menarche is associated with absence of younger siblings, absence of a father figure during early life and increased weight. Father absence during early life is also associated with early marriage, pregnancy and divorce. Choice of partner characteristics is critical to successful implementation of sexual strategies. It has been suggested that sexually dimorphic traits (including those evident in the face) signal high-quality immune function and reproductive status. Masculinity in males has also been associated with low investment in mate and offspring. Thus, women's reproductive strategy should be matched to the probability of male investment, hence to male masculinity. Our review leads us to predict associations between the rate of sexual maturation and adult preferences for facial characteristics (enhanced sexual dimorphism and attractiveness). We find for men, engaging in sex at an early age is related to an increased preference for feminized female faces. Similarly, for women, the earlier the age of first sex the greater the preference for masculinity in opposite-sex faces. When we controlled sexual dimorphism in male faces, the speed of sexual development in women was not associated with differences in preference for male facial attractiveness. These developmental influences on partner choice were not mediated by self-rated attractiveness or parental relationships. We conclude that individuals assort in preferences based on the rapidity of their sexual development. Fast developing individuals prefer opposite-sex partners with an increased level of sexually dimorphic facial characteristics.

The current study examined the contributions of general slowing and frontal decline to age differences in fluid intelligence. Participants aged 20-89 years completed Block Design, Matrix Reasoning, simple reaction time, choice reaction time, Wisconsin Card Sorting, and Tower of London tasks. Age-related declines in fluid intelligence, speed of processing, and frontal function were observed. Hierarchical regression analyses showed that the processing speed and frontal function measures accounted for significant variance in fluid intelligence performance, but there was also a residual effect of age after controlling for each variable individually as well as both variables. An additional analysis showed that the variance in fluid intelligence that was attributable to processing speed was not fully shared with the variance attributable to frontal function. These findings suggest that the age-related decline in fluid intelligence is due to general slowing and frontal decline, as well as other unidentified factors.

Aging is associated with changes in automatic processing of task-irrelevant stimuli, and this may lead to functional disturbances including repeated orienting to nonnovel events and distraction from task. The effect of age on automatic processing of time-dependent stimulus features was investigated by measurement of the auditory mismatch negativity (MMN) in younger (18-23) and older (55-85) adults. Amplitude of MMN recorded during a paradigm involving low-probability deviation in interstimulus interval (from 500 ms to 250 ms) was found to be reduced in the older group at fronto-central sites. This effect was paralleled by, and correlated to, decreased sensory gating efficiency for component N1 recorded during a separate paradigm involving alternate presentation of auditory stimuli at long (9 s) and short (0.5 s) interstimulus intervals. Further, MMN amplitude was correlated to behavioral performance on a small subset of neuropsychological tests, including the Rey Auditory Verbal Learning Test, within a group of healthy older adults. The results support the hypothesis that aging is associated with declines in automatic processing of time-dependent stimulus features, and this is related to cognitive function. These conclusions are considered in the context of age-related declines in prefrontal cortex function and associated increases in susceptibility to task-irrelevant stimuli.

The contributions of working memory, inhibition, and fluid intelligence to performance on the Tower of Hanoi (TOH) and Tower of London (TOL) were examined in 85 undergraduate participants. All three factors accounted for significant variance on the TOH, but only fluid intelligence accounted for significant variance on the TOL. When the contribution of fluid intelligence was accounted for, working memory and inhibition continued to account for significant variance on the TOH. These findings support argument that fluid intelligence contributes to executive functioning, but also show that the executive processes elicited by tasks vary according to task structure.

Memory performance by four age groups (30-45 years, 46-60 years, 61-75 years, and 76-90 years) was compared on a multi-trial verbal recall task with 20-minute and 1-day delay free recall and recognition trials. The rate of acquisition across 5 learning trials was similar for all ages except the youngest group whose performance was constrained by a ceiling effect. The level of acquisition achieved was less in the two oldest groups. Words gained across trials and words lost across trials made similar contributions to the shape of the learning curve for the acquisition trials. Subjective organization decreased with age, but remained strongly related to the number of words recalled during acquisition for all age groups. The two oldest age groups demonstrated significant declines in words recalled on the 20-minute and 1-day delay trials. A subset of the oldest group demonstrated more rapid forgetting at the 1-day delay when participants from all age conditions were matched on acquisition. Thus, many aspects of free recall were impaired with age, and variance measurement of recall showed greater inter-individual differences with increasing age. This increase in individual differences could reflect a single form of age-related memory impairment, or it could indicate that memory impairment in the elderly is due to multiple processes. The importance of testing across the life span and using tests that examine a variety of memory components and processes for establishing norms and clarifying age-related deficits are discussed.

Normal performance on the Tower of Hanoi puzzle by amnesic patients has been taken as support for viewing this problem solving task as having a nondeclarative memory component. Individuals in each decade of life between the 20s and 80s were asked to solve this puzzle four times in four sessions with intersession intervals from 1 to 7 days (Davis & Keller, 1998). Participants in their 70s and 80s were significantly impaired compared to participants in their 20s and 30s. The elderly were also significantly impaired on five immediate trials of a 15 words verbal recall test. Participants were readministered these tests an average of 6.6 years later for the elderly (n = 12) and 7.7 years later for the young (n = 11). For the Tower of Hanoi, the performance of the elderly, but not the young individuals, was significantly poorer than their original performance. For the verbal recall test, no significant change over time was detected for the young or elderly participants. These findings support the view that some nondeclarative and/or problem solving tasks demonstrate as great or greater decline with age than some declarative tasks.

The effects of age and time on nondeclarative and declarative memory in young and elderly were examined in a 10-year longitudinal study using tests of word-stem priming, incidental recall, free recall, and recognition. The elderly were significantly impaired on all tests, but no reliable longitudinal decrement by the elderly was detected for priming, incidental recall,or recognition. The elderly demonstrated a significant longitudinal decline in declarative memory as assessed by a test of free recall. While nondeclarative memory declines with age, the longitudinal findings are consistent with the view that declarative memory is more susceptible to the effects of aging.

Purpose: The purpose of this paper is to present the Omnikinetic methodology for clinical evaluation of lower extremity function, to characterize its sensitivity to errors, and to present typical data for an assessment protocol., Methods: A 5-bar, 2-degree of freedom linkage was used to model the geometry of the crank, pedal, and lower extremity. Two-degree force transducers at the pedal were used to calculate center of pressure and force applied at the foot. A Newton-Euler inverse dynamic model was used to calculate net joint torques and powers bilaterally of the ankle, knee, and hip. Ten subjects performed a high velocity evaluation protocol which served as the control. Error sensitivity was determined by adding instrumental error, hip translation, and segmental length errors to the collected data and comparing the outcome to the control., Results: All variables associated with instrumental error had mean errors under 4%. Mean errors associated with violations of the fixed hip assumption were under 15% for all variables. Mean errors associated with anthropometric measures were divided into two types: relative error (overall length unchanged, ratios of segments changed) and absolute (overall length changed, ratios of segment lengths unchanged). Relative anthropometric mean errors were under 5%. Absolute anthropometric mean errors were under 12%., Conclusion: The Omnikinetic is a new tool for bilateral lower extremity evaluation that enables the whole lower extremity to be evaluated at the joint level. Instrumental accuracy was excellent. The instrument was most sensitive to violations of the fixed hip position assumption over the last 20 degrees of knee extension.

The manual version of the Wisconsin Card Sorting Test (WCST) is the most frequently used neuropsychological instrument for differentiating normal from populations with frontal-lobe impairments. A number of computerized versions have become available, and their ability to accurately detect frontal-lobe dysfunction is based on the assumption of equivalence with the standard manual version. Accordingly, comparisons of the distribution properties of central tendency, variability, and shape between the manual version with four computerized versions of the WCST were performed (n = 22 per condition). None of the computerized versions were found to be equivalent to the manual version on all assessment measures. Given the discrepancies between the manual and computerized versions, it is concluded that the norms provided for the standard manual presentation method should not be used for the computerized versions, and for continued use of the computerized versions, new norms for computer versions need to be established. Thus, clinicians and experimenters must use caution when basing conclusions on scores from computer versions of the WCST.

The accuracy of the Rey Auditory Verbal Learning Test (RAVLT) for detecting simulated neuropsychological impairment was investigated using discriminant function analyses and cross-validation procedures. In Study 1, a discriminant function analysis, using six RAVLT variables, correctly classified 80% of 50 simulating and 50 non-simulating participants. Base rates were changed and this discriminant function was tested in Study 2 with a 33% base rate of simulation. The discriminant function correctly classified 75% of 20 simulators and 90% of 40 non-simulators, yielding an overall classification rate of 85%. To determine the generalizability of this discriminant function to a clinical sample, Study 3 compared the RAVLT performance of 20 simulating participants to that of 40 motor vehicle accident (MVA) patients. The discriminant function from Study 1 incorrectly classified 60% of the MVA patients and yielded an overall correct classification rate of 48%. The limitations associated with generalizing from analog research and the implications of varying base rates on classification accuracy are discussed.

A category classification task was administered to participants in their twenties through their eighties. Participants studied a set of high distortions of a prototype dot pattern and were then asked to choose whether or not a new set of dot patterns (random patterns, high distortions, low distortions, and the prototype) belonged to the same category of dot patterns as studied. Participants were also administered a recognition test after studying a second set of dot patterns. There were no significant differences for age groups on the pattern recognition test. In 2 of the 3 analyses of the category classification task, there were no significant age effects. However, there was a small age effect in one analysis with the young making more accurate classifications on two aspects of the task. The results are consistent with the view that small age-related effects may exist for some tests of nondeclarative memory.

A word completion priming test was used to differentiate between normal student control subjects and students instructed to malinger. Controls (n = 60) were instructed to do their best, while malingering subjects (n = 60) were instructed to fake a memory deficit for credit and possible financial compensation. Subjects initially rated and completed stems for words that had at least 10 possible completions. Thirty minutes later, subjects rated and completed stems for words that were either uniquely defined by the stem or could only be completed with a variation of the word. Simulated malingerers and controls differed significantly on response latencies (time to produce rated words-time to produce baseline words, 10 second time limit) and priming scores. Discriminant function analyses showed that as high as 92% of the controls could be correctly identified, and 73% of the malingerers could be correctly identified. These results indicate that priming tests can be used in the detection of malingering.

A category classification test was used to differentiate between normal student control participants, students instructed to malinger a memory deficit, and amnesic patients. Controls (N = 44) and amnesic patients (N = 10) were instructed to do their best, while simulators of malingering (N = 43) were instructed to fake a memory deficit for credit and possible financial compensation. Participants studied a list of high distortions of a prototype dot pattern and were then asked to choose whether or not a new set of dot patterns (random patterns, high distortions, low distortions, and the prototype) belonged to the same category of dot patterns as studied. Malingerers performed significantly worse than normal controls and amnesic patients. A discriminant function analysis showed that the classification test can be used to correctly classify participants as simulated malingerers, controls, or amnesic patients significantly higher than chance. These results indicate that a category classification test can be used in the detection of simulated malingering and that some tests of implicit memory provide a potential supplement to standard forced choice tests in the detection of malingering.

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) may play an important role in learning and memory. It has also been suggested that 5-HT abnormalities may mediate some aspects of the cognitive disorders associated with Korsakoff syndrome and Alzheimer's Disease. The effect of intracisternally applied 5-HT neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT) on learning and memory in rodents was evaluated. Three-day-old rat pups were treated with pargyline (40 mg/kg, i.p.) followed by 5,7-DHT (50 micrograms/pup) and returned to the dam for a month. At 75 days of age, rats were tested on a learning set problem in the Morris water maze for 5 days followed by 30 days of testing in a 12-arm radial maze with 8 of the 12 arms baited. In the Morris water maze, the latency to locate the hidden platform did not differ significantly for 5,7-DHT treated and control rats (F less than 1.0). Similarly, 5,7-DHT treated rats performed comparably to controls on the 12-arm radial maze (F less than 1.0). At 106 days of age the assay of tryptophan hydroxylase activity in the dorsal raphe nuclei and hippocampus showed marked reduction (86%, 78%, respectively) in 5,7-DHT treated animals compared to vehicle injected controls. Immunocytochemical analysis was consistent with the biochemical results. In 5,7-DHT treated animals there was severe loss of neurons that bind 5-HT antibody in the dorsal and medial raphe nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Many research studies produce results that falsely support a null hypothesis due to a lack of statistical power. The purpose of this research was to demonstrate selected relationships between single subject (SS) and group analyses and the importance of data reliability (trial size) on results. A computer model was developed and used in conjunction with Monte Carlo procedures to study the effects of sample size (subjects and trials), within- and between-subject variability, and subject performance strategies on selected statistical evaluation procedures. The inherent advantages of the approach are control and replication. Selected results are presented in this paper. Group analyses on subjects using similar performance strategies identified 10, 5, and 3 trials for sample sizes of 5, 10, and 20, respectively, as necessary to achieve statistical power values greater than 90% for effect sizes equal to one standard deviation of the condition distribution. SS analyses produced results exhibiting considerably less power than the group results for corresponding trial sizes, indicating how much more difficult it is to detect significant differences using a SS design. These results should be of concern to all investigators especially when interpreting nonsignificant findings.

Rats were trained for 20 days in a modified T maze to perform an invariant, tactile discrimination and a variable, delayed spatial discrimination, and then were exposed either to 30 min of transient forebrain ischemia or to low- or high-dose ibotenic acid to damage the dorsal hippocampus bilaterally. Only rats exposed to ischemia or high-dose ibotenic acid demonstrated impaired performance during 30 postoperative test days on both aspects of the task (p less than .05). Volume of hippocampal damage did not predict performance. However, the extent of CA1 pyramidal neuron loss correlated significantly with performance on the delayed spatial discrimination (p less than .01). Damage to the dentate gyrus and CA2-3 did not correlate with performance. These results support the view that the hippocampus, in particular the CA1 region, is crucial for certain types of memory performance.

Few investigators have evaluated the performance characteristics of non-running sport shoes. The purpose of this study was to assess the dynamic performance characteristics of four different shoe models during landings. Five male subjects performed 25 voluntary hanging drop landings (60 cm) onto a force platform (1000 Hz) for each of four shoe conditions (C1 and C2 = basketball shoe, C3 = running shoe, C4 = volleyball shoe). Ground reaction force data were evaluated for maximum forefoot (F1) and rearfoot (F2) impact forces as well as the respective times of occurrence of these events (T1, T2). Results of the group data analysis indicated a preferential performance rank order of C1, C3, C4, C2 although significant interaction effects were observed, indicating a need for single-subject analyses. Three techniques were incorporated to assess individual subject condition differences, all of which elicited unique rank orders for the shoes although each identified C1 as the "best" shoe condition. The results of the study support the necessity for within-subject analyses conducted with an adequate number of trials when attempting to detect subtle performance differences that may exist between various sport shoes. Whether the observed statistically significant differences are biomechanically meaningful remains an important unanswered question.

The effects of age on implicit memory were assessed in elderly young adults using 2 priming procedures. Subjects also completed the WAIS-R, 3 tests to assess frontal lobe function, and 2 recall and 2 recognition tests of explicit memory. In Experiment 1, subjects were exposed to the low-frequency member of a homophone pair in a test purported to assess general knowledge. Subsequently, subjects completed a spelling test that contained the previously presented homophones to assess priming. Young subjects demonstrated priming (p less than .01). Elderly subjects demonstrated a high baseline that may have obscured priming. In Experiment 2, subjects from each decade of life from the 20s through the 80s were given a word-stem completion test of priming. All age conditions demonstrated an effect of priming (p less than .01). However, subjects in their 70s and 80s demonstrated lower priming scores (p less than .05). Elderly subjects were also impaired on immediate-and delayed-recall tests. These results suggest an age-related decline in both implicit and explicit memory.

Polycythaemia has developed in 10 of 59 regularly reviewed patients with renal transplants surviving more than three months. The pathology of the raised haemoglobin level was heterogeneous. Three patients had a picture characterized by a normal red cell mass and reduced plasma volume. Seven patients had a raised red cell mass; in 3 of these this was associated with a period of abnormal liver function and fitted with the state of raised red cell mass in association with hepatic transaminitis. The remaining 4 patients form a unique, previously undefined group with no features to explain the underlying aetiology of the polycythaemia. The patients had a trouble-free post-transplant course with early establishment of graft function. It is proposed, from the data obtained from in vitro culture studies, that the early return of good renal function allows the erythroid compartment to expand in response to circulating erythropoietin. The establishment of an erythron of increased size allows for a persistently raised haemoglobin in the presence of normal erythropoietin levels.

Many findings support the hypothesis that formation of long-term memory requires synthesis of proteins in the nervous system close to the time of learning. This hypothesis has been challenged recently by reports that the protein synthesis inhibitor cycloheximide (CYC) injected 2 hr prior to passive avoidance training in mice or rats attenuated the memory impairment induced by a usually amnestic dose of CYC administered 30 min pretraining. To investigate the reports of a "protective" effect of the prior injection, we attempted to replicate them and test their generality. For replication we administered either paired injections of CYC--120 mg/kg 2 hr prior to training and 30 mg/kg 30 min prior to training--or single injections of CYC (either 120 mg/kg or 30 mg/kg) 30 min pretraining and tested for retention of the passive avoidance habit either 1 or 7 days later. No attenuation of amnesia was observed at 1 day tests. Attenuation of amnesia following the double injection of CYC was observed at 7 day tests. When another protein synthesis inhibitor, anisomycin, was used in the same experimental design, there was no "protective" effect; two injections of anisomycin produced greater memory impairment for the passive avoidance habit than did the single low dose. Also, for active avoidance training, two successive injections of CYC caused significantly greater amnesia than did a single dose; this is the opposite of a "protective" effect. We suggest that the reported "protective" effect of CYC on memory is an as yet unexplained phenomenon that does not generalize to other antibiotic drugs and is specific to the passive avoidance task.

Rats exposed to 30 minutes of four-vessel occlusion reliably develop severe bilateral CA1 hippocampal injury; under certain conditions of radial maze training, such rats perform the reference memory component as well as controls yet perform the working memory component worse than controls. Reference memory is thought to depend on invariable and working memory on variable spatial information. We assessed the effect of training before ischemia. In Experiment 1, rats trained for 36 trials on 12-arm radial mazes before ischemia demonstrated a persistent impairment on the working memory task but eventually performed the reference memory task comparable to controls. Ischemic rats made more working memory errors as the number of choices increased. This pattern of working memory errors was similar to that in controls except, as expected, ischemic rats made many more errors. In Experiment 2, training for 80 trials before ischemia in rats decreased the severity of both the working and the reference memory impairment. Ischemia did not affect motor behavior in either experiment. These results characterize the working memory deficit in ischemic rats and demonstrate the importance of experimental factors, particularly in the design of treatment strategies to reduce functional impairments caused by ischemia.

Short-term memory of a spatial task by male Fischer 344 rats at 3, 12, and 24 months of age was examined in a radial 8-arm maze. Performance by 24 month old rats was significantly poorer than that of 3 or 12 month old rats. 3,4-Diaminopyridine (1000 pmole/kg), a compound that stimulates acetylcholine release, significantly improved 8-arm maze performance by 24 month old rats. Thus, an age-related deficit in short-term memory for a spatial task can be ameliorated by a compound that stimulates acetylcholine release.

Inhibition of cerebral protein synthesis impairs long-term memory in a variety of species and tasks. Recently it was reported that subcutaneous injection of the protein synthesis inhibitor cycloheximide impaired short-term retention, measured 10 min after training in a passive avoidance task. To examine the possibility that inhibition of cerebral protein synthesis may sometimes disrupt short-term memory, mice were injected subcutaneously with cycloheximide (120 mg/kg) or anisomycin (150 mg/kg), or bitemporally with cycloheximide or anisomycin (100 mug/side) and given one training trial in a passive avoidance box. Subcutaneously injected cycloheximide reduced step-through latencies 10 min after training as reported previously, but anisomycin or bitemporally injected cycloheximide did not. All 4 drug groups exhibited impaired long-term memory. Since the results obtained at short intervals after training varied depending on the drug and route of injection, the impairment produced by subcutaneous cycloheximide at 10 min after training cannot be attributed to inhibition of cerebral protein synthesis. It is suggested that performance at short intervals after training reflects drug side effects on step-through behavior. By contrast, the impairment obtained at long intervals after training is consistent with the hypothesis that cerebral protein synthesis is required for formation of long-term memory.

Retrograde amnesia following inhibition of cerebral protein synthesis has generally been explained as either a failure of consolidation or impairment of a retrieval mechanism. Major evidence for the retrieval hypothesis is provided by studies which utilize a reminder (usually footshock) to attenuate the effect of the protein inhibitor. To examine this question, mice were injected subcutaneously with anisomycin (1 mg/animal, 7 mg/animal, or 1 mg/animal every 2 hr x 7) and given one training trial in a passive avoidance box. All animals received a single retention test on each of four consecutive days, starting either 1, 7, or 21 days after training. One-half of the mice in each group received a footshock reminder 1 hr after their initial test. The footshock reminder did not attenuate the inhibitor-induced amnesia, but multiple testing did produce partial recovery in animals demonstrating some memory of training (both Saline and Anisomycin animals). Animals injected with anisomycin whose testing began 1 day after training demonstrated partial recovery irrespective of drug dosage level. The extent of amnesia and recovery were dependent upon both drug dosage and training-test interval. Implications for the consolidation and retrieval hypotheses are discussed.

Male Swiss albino CD-1 mice given a single subcutaneous injection of a cerebral protein synthesis inhibitor, anisomycin (ANI; 1 mg/animal), 20 min prior to a single trial of passive avoidance training demonstrated impaired retention at tests given 3 hr, 6 hr, 1 day, and 7 days after training. Retention was not significantly different from that of saline controls when tests were given .5 or 1.5 hr after training. Prolonging inhibition of brain protein synthesis by giving either one or two additional injections of ANI at 2 hr or at 2 and 4 hr after training did not prolong good retention performance. The temporal development of impaired retention in ANI-treated mice could not be accounted for by drug dosage, duration of protein synthesis inhibition, or nonspecific sickness at test. In contrast to the suggestion that protein synthesis inhibition prolongs short-term memory, the results of this experiment indicate that short-term memory is not prolonged by antibiotic drugs that inhibit cerebral protein synthesis. All evidence seems consistent with the hypothesis that short-term memory is independent of protein synthesis and that the establishment of long-term memory depends on protein synthesis during or shortly after training.

Acquisition of reference and working memory was evaluated in an animal model of cerebral ischemia. Rats were subjected to 30 minutes of transient forebrain ischemia, allowed to recover, and then tested for 95 trials on an 8-arm maze with 5 arms baited. During the 95 trials post ischemic (PI) rats made significantly more working and reference errors than controls (p less than 0.05). However, an analysis of the last 20 trials (75-95) showed that while PI rats and control rats had comparable reference memory (p greater than 0.8). PI rats tended to have a persistent working memory deficit compared to controls (p less than 0.06). Subsequent morphologic analysis showed that PI rats had almost complete loss of pyramidal neurons in the anterior CA1 region of the hippocampus, moderate to severe loss in mid-dorsal posterior hippocampus, and less damage to the dorsolateral striatum. These results suggest that the PI animal is a reasonable model for the permanent behavioral impairment and pathologic damage found in some human survivors of cardiac arrest.