A latent variable approach to executive control in healthy ageing

It is a well-established finding that the central executive is fractionated in at least three separable component processes: Updating, Shifting, and Inhibition of information (Miyake et al., 2000). However, the fractionation of the central executive among the elderly has been less well explored, and Miyake's et al. latent structure has not yet been integrated with other models that propose additional components, such as access to long-term information. Here we administered a battery of classic and newer neuropsychological tests of executive functions to 122 healthy individuals aged between 48 and 91 years. The test scores were subjected to a latent variable analysis (LISREL), and yielded four factors. The factor structure obtained was broadly consistent with Miyake et al.'s three-factor model. However, an additional factor, which was labeled 'efficiency of access to long-term memory', and a mediator factor ('speed of processing') were apparent in our structural equation analysis. Furthermore, the best model that described executive functioning in our sample of healthy elderly adults included a two-factor solution, thus indicating a possible mechanism of dedifferentiation, which involves larger correlations and interdependence of latent variables as a consequence of cognitive ageing. These results are discussed in the light of current models of prefrontal cortex functioning.     

Changing the general factor of personality and the c-fos gene expression with methylphenidate and self-regulation therapy

A deepening in the biological nature of the general factor of personality (GFP) is suggested: the activation level of the stress system is here represented by the gene expression of c-fos. The results of a single case experimental design are reported. A model of four coupled differential equations that explains the human personality dynamics as a consequence of a single stimulant drug intake has been fitted to psychological and biological experimental data. The stimulant-drug conditioning and its adaptation to the considered mathematical model is also studied for both kinds of measures. The dynamics of the c-fos expression presents a similar pattern to the dynamics of the psychological measures of personality assessed by the GFP-FAS (Five-Adjective Scale of the General Factor of Personality) as a consequence of a single dose of stimulant drug (methylphenidate). The model predicts similar dynamic patterns for both psychological and biological measures. This study proves that describing mathematically the dynamics of the effects of a stimulant drug as well as the effects of a conditioning method on psychological or subjective variables and on gene expression is possible. It verifies the existence of biological mechanisms underlying the dynamics of the General Factor of Personality (GFP).     

Psycho-physiological impact on women with chronic fatigue syndrome in the context of their couple relationship

The quality of dyadic adjustment is likely to play an important role in patients' relational problems and may also be associated with the clinical presentation of chronic fatigue syndrome (CFS) symptoms. The objective of this study was (1) to determine whether CFS patients and their partners have similar perceptions of their dyadic adjustment and (2) to evaluate whether the influence of dyadic satisfaction in women with CFS, as well as common psychological parameters such as anxiety, may correlate with physiological responses at rest and/or when performing very low intensity exercise. Forty females with CFS and their partners completed the Dyadic Adjustment Scale, the State-Trait Anxiety Inventory, and the Hospital Anxiety and Depression scale. The cardiovascular adaptation of patients was evaluated during resting conditions and on a precalibrated cycle ergometer while performing very low intensity exercise. Patients and partners had similar perceptions of their marital relationship. Both at rest and during very low workload, various physiological parameters in the patient group showed statistical correlations with certain psychological parameters. Several psychological variables, such as anxiety and dyadic adjustment, were associated with the cardioventilatory response monitored at rest and during very low intensity exercise. Further studies are needed to determine the nature of this association.     

Recognition memory deficits in mild cognitive impairment

ABSTRACT There is no agreement on the pattern of recognition memory deficits characteristic of patients diagnosed with mild cognitive impairment (MCI). Whereas lower performance in recollection is the hallmark of MCI, there is a strong controversy about possible deficits in familiarity estimates when using recognition memory tasks. The aim of this research is to shed light on the pattern of responding in recollection and familiarity in MCI. Five groups of participants were tested. The main participant samples were those formed by two MCI groups differing in age and an Alzheimer's disease group (AD), which were compared with two control groups. Whereas one of the control groups served to assess the performance of the MCI and AD people, the other one, composed of young healthy participants, served the purpose of evaluating the adequacy of the experimental tasks used in the evaluation of the different components of recognition memory. We used an associative recognition task as a direct index of recollection and a choice task on a pair of stimuli, one of which was perceptually similar to those studied in the associative recognition phase, as an index of familiarity. Our results indicate that recollection decreases with age and neurological status, and familiarity remains stable in the elderly control sample but it is deficient in MCI. This research shows that a unique encoding situation generated deficits in recollective and familiarity mechanisms in mild cognitive impaired individuals, providing evidence for the existence of deficits in both retrieval processes in recognition memory in a MCI stage.     

The effects of gender on the retrieval of episodic and semantic components of autobiographical memory

Despite consistent evidence that women exhibit greater episodic memory specificity than men, little attention has been paid to gender differences in the production of episodic details during autobiographical recall under conditions of high and low retrieval support. Similarly the role of gender on the production of semantic details used to support autobiographical memory recollections of specific events has been largely unexplored. In the present study an undergraduate sample of 50 men and 50 women were assessed using the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). Women recalled more episodic information compared to men in the high retrieval support condition, whereas no gender differences were found in the low retrieval support condition. In addition, women produced more repetitions compared to men in the high retrieval support condition. No gender differences were found in the production of semantic details. These results are interpreted in terms of gender differences in encoding and reminiscence practices. This research adds to the literature on gender differences in memory recall and suggests that gender is an important variable in explaining individual differences in AM recall.     

Processing of distractors inside and outside the attentional focus in a priming procedure

A priming procedure was used to study the processing of distractors located either inside (between the location of two targets) or outside (peripherally to the locations of the targets) the focus of attention. The stimuli were five-letter arrays, and participants had to decide whether two marked target letters were the same or different. In Experiments 1 and 2, positive priming was obtained both when targets and in-distractors in primes repeated as targets in probes; negative priming was found when out-distractor primes repeated as targets in probes. In Experiment 3, we also manipulated the match in letter case from primes to probes. In-distractors produced reliable positive priming, irrespective of whether the letters matched in case. In contrast out-distractors produced negative priming but only when the letters had the same case in primes and probes. These results are attributed to a spatial attention process operating (in this case) on low-level visual features, and an object-based selection process that enables more abstract information to be processed for selected stimuli.     

Adult Age Differences in Attention to Semantic Context

ABSTRACT

In three experiments age differences in attention to semantic context were examined. The performance of younger adults (ages 18–29 years) and older adults (ages 60–79 years) on a semantic priming task indicated that both age groups could use information regarding the probability that a prime and target would be related to flexibly anticipate the target category given the prime word (Experiment 1). The timing by which target expectancies were reflected in reaction time performance was delayed for older adults as compared to younger adults, but only when the target was expected to be semantically unrelated to the prime word (Experiment 2). When the target and prime were expected to be semantically related, the time course of priming effects was similar for younger and older adults (Experiment 3). Together the findings indicate that older adults are able to use semantic context and the probability of stimulus relatedness to anticipate target information. Although aging may be associated with a delay in the timing by which controlled expectancies are expressed, these findings argue against an age-related decline in the ability to represent contextual information.     

Contextual Pavlovian conditioning in the crab Chasmagnathus

In contextual conditioning, a complex pattern of information is processed to associate the characteristics of a particular place with incentive or aversive reinforcements. This type of learning has been widely studied in mammals, but studies of other taxa are scarce. The context-signal memory (CSM) paradigm of the crab Chasmagnathus has been extensively used as a model of learning and memory. Although initially interpreted as habituation, some characteristics of contextual conditioning have been described. However, no anticipatory response has been detected for animals exposed to the training context. Thus, CSM could be interpreted either as an associative habituation or as contextual conditioning that occurs without a context-evoked anticipatory response. Here, we describe a training protocol developed for contextual Pavlovian conditioning (CPC). For each training trial, the context (conditioned stimulus, CS) was discretely presented and finished together with the unconditioned stimulus (US). In agreement with the CSM paradigm, a robust freezing response was acquired during the 15 training trials, and clear retention was found when tested with the US presentation after short (2 and 4 h) and long (1–4 days) delays. This CPC memory showed forward but not simultaneous presentation conditioning and was context specific and protein synthesis dependent. Additionally, a weak CPC memory was enhanced during consolidation. One day after training, CPC was extinguished by repeated CS presentation, while one presentation induced a memory labilisation–reconsolidation process. Finally, we found an anticipatory conditioned response (CR) during the CS presentation for both short-term (4 h) and long-term memory (24 h). These findings support the conditioning nature of the new paradigm.     

Hope and Burden among Latino Families of Adults with Schizophrenia

This study examined hope and family burden among Latino families of individuals with schizophrenia. The sample consisted of 54 family members, one family member per outpatient adult recruited from public mental health programs in a diverse urban community. Hierarchical linear regression analyses were used to test the hypothesis that the family member's increased hope for the patient's future would be associated with decreased family burden beyond effects explained by the patient's length of illness and severity of symptoms. Results supported the study hypothesis. Family hope for the patient's future was associated with four of five types of family burden. Findings point to the prominent role of hope as a source of resilience for Latino families dealing with severe mental illness of a loved one.