Study of behavioural and neural bases of visuo‐spatial working memory with an fMRI paradigm based on an n‐back task

The goal of this study was to propose a new functional magnetic resonance imaging (fMRI) paradigm using a language‐free adaptation of a 2‐back working memory task to avoid cultural and educational bias. We additionally provide an index of the validity of the proposed paradigm and test whether the experimental task discriminates the behavioural performances of healthy participants from those of individuals with working memory deficits. Ten healthy participants and nine patients presenting working memory (WM) deficits due to acquired brain injury (ABI) performed the developed task. To inspect whether the paradigm activates brain areas typically involved in visual working memory (VWM), brain activation of the healthy participants was assessed with fMRIs. To examine the task's capacity to discriminate behavioural data, performances of the healthy participants in the task were compared with those of ABI patients. Data were analysed with GLM‐based random effects procedures and t‐tests. We found an increase of the BOLD signal in the specialized areas of VWM. Concerning behavioural performances, healthy participants showed the predicted pattern of more hits, less omissions and a tendency for fewer false alarms, more self‐corrected responses, and faster reaction times, when compared with subjects presenting WM impairments. The results suggest that this task activates brain areas involved in VWM and discriminates behavioural performances of clinical and non‐clinical groups. It can thus be used as a research methodology for behavioural and neuroimaging studies of VWM in block‐design paradigms.     

A mechanistic perspective on canonical neural computation

Although it has been argued that mechanistic explanation is compatible with abstraction (i.e., that there are abstract mechanistic models), there are still doubts about whether mechanism can account for the explanatory power of significant abstract models in computational neuroscience. Chirimuuta has recently claimed that models describing canonical neural computations (CNCs) must be evaluated using a non-mechanistic framework. I defend two claims regarding these models. First, I argue that their prevailing neurocognitive interpretation is mechanistic. Additionally, a criterion recently proposed by Levy and Bechtel to legitimize mechanistic abstract models, and also a criterion proposed by Chirimuuta herself aimed to distinguish between causal and non-causal explanation, can be employed to show why these models are explanatory only under this interpretation (as opposed to a purely mathematical or non-causal interpretation). Second, I argue that mechanism is able to account for the special epistemic achievement implied by CNC models. Canonical neural components contribute to an integrated understanding of different cognitive functions. They make it possible for us to explain these functions by describing different mechanisms constituted by common basic components arranged in different ways.     

Latent inhibition and asymmetrical visual-spatial attention in children with ADHD.

The research was designed to determine whether the purported hemispheric asymmetries that are associated with attention deficit/hyperactivity disorder (ADHD) affect performance on a selective attention visual search task, and whether any obtained asymmetry will be modulated by methylphenidate. Two groups of children (8-15 years) with ADHD, one with methylphenidate treatment (ADHD+) and one without (ADHD+), were compared to matched controls on a two-stage visual search task. The task assessed right-left visual field asymmetries and the effects of changing a previous distractor into a target. Such a procedure, related to latent inhibition (LI; poorer performance to a previously irrelevant stimulus than to a novel one), can provide evidence for dysfunctional processing of irrelevant stimuli. All three groups exhibited the LI effect. The ADHD group, however, exhibited less LI for left- than right-side targets, an effect absent in the control and ADHD+ groups, suggesting a lateralized attentional deficit for ADHD+ that was normalized by methylphenidate.     

Borderline personality traits in nonclinical young adults

The main purpose of this study was to explore the dimensionality of the borderline personality disorder in nonclinical young adults by means of the Borderline Personality Questionnaire (BPQ; Poreh et al., 2006). We also studied the phenotypic expression of the borderline personality traits as a function of participants' gender and age, and the relationship between BPQ subscales and measures of depressive symptoms, anxiety, stress, hallucinatory predisposition, and paranoid ideation. The sample comprised 809 young adults, 562 (69.5%) were women, with a mean age of 20.2 years (SD = 2.9). The results indicate that the BPQ self-report has adequate psychometric properties. The levels of internal consistency for the BPQ subscales ranged between .78 and .93. Analysis of the internal structure of the BPQ subscales yielded a one-dimensional solution. In contrast, second-order principal components analysis at the item level yielded a five-dimensional solution. Likewise, statistically significant differences in the mean scores of the borderline personality traits as a function of participants' gender and age were found. The BPQ subscales correlated significantly with measures of depression, anxiety, stress, paranoid ideation, and hallucinatory predisposition. These results help to improve our understanding of the dimensional structure of the borderline personality in the general population. Future research should continue to identify participants who are at risk for the development of borderline personality disorder and facilitating the development of early detection and prevention programs.     

Sleep patterns of 7‐week‐old infants at familial risk for attention deficit hyperactivity disorder

Sleep patterns of 26 seven‐week‐old boys at familial risk for attention deficit hyperactivity disorder (ADHD) and 18 control infants were compared by objective (actigraph) and subjective (maternal sleep diary) measures, over five consecutive 24‐hr periods. Actigraph findings indicated that the groups differed on stability (SD) of quiet sleep only during the day. Reports in maternal sleep diaries indicated that they also differed on stability of waking and stability of sleep duration, again only during the day. No group differences were found in terms of average scores, whether calculated for the entire 24‐hr periods, for nights, or for days. Mothers in the risk group reported that fathers were less involved in infant care than did those in the control group. These findings suggest that as early as 7 weeks of age, infants at risk for ADHD differ from controls only on stability of their sleep patterns during the day, when environmental regulatory factors are more intensive.     

Severe intimate partner violence risk prediction scale-revised

The aim of this study was to describe the psychometric properties of the Severe Intimate Partner Violence Risk Prediction Scale and to revise it in order to ponderate the 20 items according to their discriminant capacity and to solve the missing item problem. The sample for this study consisted of 450 male batterers who were reported to the police station. The victims were classified as high-risk (18.2%), moderate-risk (45.8%) and low-risk (36%), depending on the cutoff scores in the original scale. Internal consistency (Cronbach's alpha=.72) and interrater reliability (r=.73) were acceptable. The point biserial correlation coefficient between each item and the corrected total score of the 20-item scale was calculated to determine the most discriminative items, which were associated with the context of intimate partner violence in the last month, with the male batterer's profile and with the victim's vulnerability. A revised scale (EPV-R) with new cutoff scores and indications on how to deal with the missing items were proposed in accordance with these results. This easy-to-use tool appears to be suitable to the requirements of criminal justice professionals and is intended for use in safety planning. Implications of these results for further research are discussed.     

Cross-Category Friendships and Postformal Thought among College Students

Theories of postformal thought (PFT) suggest that cognitive development is enhanced by social interactions where differences must be negotiated. Friendships provide the potential for complex social interactions and are an ideal context in which to explore the relation between cognitive development and the negotiation of social differences. The present research is the first to directly explore the relation between close cross-category friendships and level of postformal cognitive reasoning among college students. Participants from two universities completed questionnaires assessing PFT and friendship characteristics. Results indicate that individuals reported more same-category versus cross-category friendships. This was true for sex, ethnicity, social class, sexual orientation, and age. In addition, individuals high in PFT had more social category differences in their existing close friendships than individuals low in PFT.     

Systemic administration of a nitric oxide synthase inhibitor impairs fear sensitization in the plus-maze

The aim of the present study was to evaluate the occurrence of fear sensitization in rats previously treated with an inhibitor of the NO syntheses and submitted to Trial1/Trial2 plus-maze (PM) procedure. Male Wistar rats received a systemic treatment with N(omega)-nitro-L-Arginine-methyl ester (L-NAME; 5, 10 or 50 mg kg(-1)) and were submitted to PM Trial1. In the following day the animals were re-exposed to the PM with no drug administration (Trial2). Some standards spatial-temporal measures, such as the percentage of entries (% Open arm entries) and time spent (% Open arm time) in the open arms and risk assessment frequency were recorded and used to estimate the animal level of fear sensitization in PM Trial2. The results showed that animals receiving L-NAME (50 mg kg(-1)) displayed increased % Open arm entries and % Open arm time in Trial2 in relation to the group receiving 0.9% saline, which is compatible with impaired fear/anxiety acquisition during Trial1/Trial2 PM procedure. In addition, rats treated with L-NAME (50 mg kg(-1)) exhibited low level of risk assessment in Trial2 in relation to the group treated with 0.9% saline, which indicates low level of fear/anxiety during PM re-exposure. The number of entries into the enclosed arms was not changed by any L-NAME treatment, which suggests no bias of the drug treatments on animal locomotor activity. The data suggest that NO synthesis may mediate the fear sensitization process in the PM.