An attentional approach to study mental representations of different parts of the hand

The aim of this study is to investigate whether the fingers are represented separately from the palm. An exogenous spatial orientation paradigm was used where participants had to detect a tactile stimulus that could appear on the palm, the middle finger or the ring finger of the left hand. The tactile target was preceded by a non-predictive cue using different stimulus-onset asynchronies (SOA). We observed a Facilitation Effect in the palm and Inhibition of Return (IOR) for fingers using a short cue-target SOA, whereas the IOR was found in fingers and palm in long cue-target SOA. Also we observed a ‘Cue above Target’ effect (facilitation effect when the Cue had appeared distal to the target location in a vertical line) at the long SOA. Together, we suggest that the general pattern of results supports the proposed hypothesis about the different mental representation of fingers and palms, but with a considerable and hierarchical interrelation between them.     

Potential consequences of abandonment in preschool-age: Neuropsychological findings in institutionalized children

Objective: Several longitudinal studies had shown that early deprivation and institutionalization during the first six months of life affects the emotional, cognitive, social and neurophysiologic development. Nevertheless, our understanding of possible similar effects of delayed institutionalization, in preschool-age remains unclear to this day. The goal of this study is to evaluate the cognitive performance of institutionalized children with history of preschool-age physical abandonment. Method: 18 male institutionalized children with history of abandonment during the preschool-age (2-5 years old) and comparison group matched by age, handedness, gender, educational and socioeconomic level were tested on multiple tasks of attention, memory and executive functions. Results: We found a cognitive impairment in the institutionalized children in several measures of attention, memory and executive functions. This is the first report of cognitive impairment related to late abandonment and institutionalization effects (after 2 years old), extending the already known effects on early institutionalization. Conclusions: This preliminary study suggests that environmental factors including abandonment and institutional care, can affect not only the infancy period, but also the preschool period providing new insights into our understanding of neurocognitive development.     

Does physical activity reduce risk for Alzheimer's disease through interaction with the stress neuroendocrine system?

Lack of physical activity (PA) is a risk factor for Alzheimer's disease (AD), and PA interventions are believed to provide an effective non-pharmacological approach for attenuating the symptoms of this disease. However, the mechanism of action of these positive effects is currently unknown. It is possible that the benefits may be at least partially mediated by the effects on the neuroendocrine stress system. Chronic stress can lead to dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, leading to aberrant basal and circadian patterns of cortisol secretion and a cascade of negative downstream events. These factors have been linked not only to reduced cognitive function but also increased levels of amyloid-β plaques and protein tau "tangles" (the neuropathological hallmarks of AD) in the non-demented mouse models of this disease. However, there is evidence that PA can have restorative effects on the stress neuroendocrine system and related risk factors relevant to AD. We explore the possibility that PA can positively impact upon AD by restoring normative HPA axis function, with consequent downstream effects upon underlying neuropathology and associated cognitive function. We conclude with suggestions for future research to test this hypothesis in patients with AD.     

Enhancing effects of acute psychosocial stress on priming of non-declarative memory in healthy young adults

Social stress affects cognitive processes in general, and memory performance in particular. However, the direction of these effects has not been clearly established, as it depends on several factors. Our aim was to determine the impact of the hypothalamus-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) reactivity to psychosocial stress on short-term non-declarative memory and declarative memory performance. Fifty-two young participants (18 men, 34 women) were subjected to the Trier Social Stress Task (TSST) and a control condition in a crossover design. Implicit memory was assessed by a priming test, and explicit memory was assessed by the Rey Auditory Verbal Learning Test (RAVLT). The TSST provoked greater salivary cortisol and salivary alpha-amylase (sAA) responses than the control task. Men had a higher cortisol response to stress than women, but no sex differences were found for sAA release. Stress was associated with an enhancement of priming but did not affect declarative memory. Additionally, the enhancement on the priming test was higher in those whose sAA levels increased more in response to stress (r(48)?=?0.339, p?=?0.018). Our results confirm an effect of acute stress on priming, and that this effect is related to SNS activity. In addition, they suggest a different relationship between stress biomarkers and the different memory systems.     

Individual differences and state effects on mind-wandering: Hypnotizability, dissociation, and sensory homogenization

Consciousness alterations can be experienced during unstructured, monotonous stimuli. These effects have not been linked to particular cognitive operations; individual differences in response to such stimulation remain poorly understood. We examined the role of hypnotizability and dissociative tendencies in mind-wandering (MW) during a sensory homogenization procedure (ganzfeld). We expected that the influence of ganzfeld on MW would be more pronounced among highly hypnotizable individuals (highs), particularly those high in dissociative tendencies. High and low hypnotizables, also stratified by dissociation, completed the sustained attention to response task during ganzfeld and control conditions. High dissociative highs made more commission errors during ganzfeld, suggesting increased MW, whereas the other groups displayed the opposite pattern. Increases in commission errors from the control condition to ganzfeld were associated with more alterations in consciousness and negative affect, but only among highs. Sensory homogenization had opposite effects on MW depending on the interaction of hypnotizability and dissociation.     

How daydreaming relates to life satisfaction, loneliness, and social support: the importance of gender and daydream content

Daydreaming appears to have a complex relationship with life satisfaction and happiness. Here we demonstrate that the facets of daydreaming that predict life satisfaction differ between men and women (Study 1; N=421), that the content of daydreams tends to be social others (Study 2; N=17,556), and that who we daydream about influences the relation between daydreaming and happiness variables like life satisfaction, loneliness, and perceived social support (Study 3; N=361). Specifically, daydreaming about people not close to us predicts more loneliness and less perceived social support, whereas daydreaming about close others predicts greater life satisfaction. Importantly, these patterns hold even when actual social network depth and breadth are statistically controlled, although these associations tend to be small in magnitude. Individual differences and the content of daydreams are thus important to consider when examining how happiness relates to spontaneous thoughts.     

Mind your words: positive and negative items create method effects on the Five Facet Mindfulness Questionnaire

Mindfulness, a construct that entails moment-to-moment effort to be aware of present experiences and positive attitudinal features, has become integrated into the sciences. The Five Facet Mindfulness Questionnaire (FFMQ), one popular measure of mindfulness, exhibits different responses to positively and negatively worded items in nonmeditating groups. The current study employed confirmatory factor analysis with a large undergraduate sample to examine the validity of a hierarchical mindfulness model and whether response patterns related to item wording arose from method effects. Results indicated that a correlated facets model better explained the data and that negative and positive wording constituted substantive method effects. This study suggests that the FFMQ measures components that may relate to, but do not seem to directly reflect, a latent variable of mindfulness. The authors recommend against the use of an FFMQ total score, favoring individual scale scores, and further examination of method effects in mindfulness scales.     

Memory traces compete under regimes of limited Arc protein synthesis: Implications for memory interference

Recently encoded information can be lost in the presence of new information, a process called 'retrograde interference'. Retrograde interference has been extensively described for more than a century; however, little is known about its underlying mechanisms. Different approaches agree on the need of the synthesis of plasticity related proteins (PRPs) to consolidate a long-term memory (LTM). Our hypothesis is that when PRPs are limited, interference of a task over LTM formation of another may be due to the utilization of protein resources common to both tasks. Here, by combining the tasks of inhibitory avoidance (IA) and open field (OF) exploration in rats, we show that memory traces compete for their stabilization if PRPs are limited. As a result, LTM is formed for only one of the tasks with a consequent decrease in the memory for the other. Furthermore, infusing Arc antisense oligonucleotide into the dorsal hippocampus, we found that Arc is necessary for LTM formation of these two types of learning tasks and is one of the PRPs that can be shared between them when animals are trained in both OF and IA. In sum, these findings suggest that under conditions of reduced protein availability, a learning task interferes with LTM formation of another by using the available PRPs.     

Opposite actions of dopamine on aversive and appetitive memories in the crab

The understanding of how the reinforcement is represented in the central nervous system during memory formation is a current issue in neurobiology. Several studies in insects provide evidence of the instructive role of biogenic amines during the learning and memory process. In insects it was widely accepted that dopamine (DA) mediates aversive reinforcements. However, the idea of DA being exclusively involved in aversive memory has been challenged in recent studies. Here, we study the involvement of DA during aversive and appetitive memories in the crab Chasmagnathus. We found that DA-receptor antagonists impair aversive memory consolidation, in agreement with previous reports in insects, while administration of DA facilitates memory formation after a weak training protocol. In contrast, DA treatment during appetitive training was found to impair formation of long-term appetitive memory. In addition, as a first step in elucidating the neuroanatomical correlates of DA action on memory, we mapped dopaminergic neurons in the central nervous system of the crab. Results of the current study, together with those obtained in a previous work about the role of octopamine (OA), suggest that both amines (DA and OA) play a dual action in memory processes. On the one hand, DA and OA mediate the aversive and the appetitive signals, respectively, throughout training, while on the other hand, they interfere with the formation of memory of the opposite sign (DA in appetitive and OA in aversive). Our results support a new understanding about the way appetitive and aversive stimuli are processed during memory formation to ensure adaptive behavior.