Maxciel Zortea

Anodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex modulates attention and pain in fibromyalgia: randomized clinical trial

Cognitive dysfunction in fibromyalgia patients has been reported, especially when increased attentional demands are required. Transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been effective in modulating attention. We tested the effects of a single session of tDCS coupled with a Go/No-go task in modulating three distinct attentional networks: alertness, orienting and executive control. Secondarily, the effect on pain measures was evaluated. Forty females with fibromyalgia were randomized to receive active or sham tDCS. Anodal stimulation (1 mA, 20 min) was applied over the DLPFC. Attention indices were assessed using the Attention Network Test (ANT). Heat pain threshold (HPTh) and tolerance (HPTo) were measured. Active compared to sham tDCS led to increased performance in the orienting (mean difference [MD] = 14.63) and executive (MD = 21.00) attention networks. There was no effect on alertness. Active tDCS increased HPTh as compared to sham (MD = 1.93) and HPTo (MD = 1.52). Regression analysis showed the effect on executive attention is mostly independent of the effect on pain. DLPFC may be an important target for neurostimulation therapies in addition to the primary motor cortex for patients who do not respond adequately to neurostimulation therapies.

Estudo comparativo das associações semânticas de palavras entre adultos jovens e idosos

The number of studies on word associations have increased recently. However, little agreement exists about age differences in relation to these associations. The semantic word associations of 108 adult college students (M = 22.17; SD = 6.04), and 57 elderly (M = 70.89; SD = 6.87) were compared using a semantic word association task. The strength between the stimuli and the strongest word associated were similar for both groups. The number of different words and the total amount of associated words were higher for the adults. Finally, the diversity index of responses was higher for the adults. Future research on memory and language can consider these age differences when developing tasks with verbal stimuli.

Graph analysis of semantic word association among children, adults, and the elderly

This study used graph analysis to investigate how age differences modify the structure of semantic word association networks of children and adults and if the networks present a small-world structure and a scale-free distribution which are typical of natural languages. Three age groups of Brazilian Portuguese speakers (children, adults and elderly people) participated in the experiment. Quantitative and qualitative measures suggested that adults and elderly speakers have similar network structures. Childrens network showed fewer nodes, connections and clusters, and longer inter-node distances. All networks presented a small-world structure, but they did not show entirely scale-free distributions. These results suggest that from childhood to adulthood, there is an increase not only in the number of words semantically linked to a target but also an increase in the connectivity of the network.

Tarefa experimental de metamemória para avaliar monitoramento e controle de memória

Experimental tasks for the assessment of monitoring and control memory processes allow the online exam of these abilities. In the national field these tasks still need to be elaborated in order to facilitate and stimulate future research projects. This article presents the steps for the elaboration of a task for examining memory monitoring and control processes. In Study 1 we describe the selection of 100 stimuli (cue-target word pairs) and its psycholinguistic aspects. Study 2 presents data of a pilot-study of the task with ten adults, focusing on the evaluation of monitoring processes. In Study 3 we show data of monitoring and control processes of a pilot-study with 12 undergraduate students as well as a clinical case of stroke and two neurologically unimpaired elderly people. Results suggest the need of two different versions of the task for different populations, which would allow enough variance within and between participants. In addition, other preliminary findings relevant for current metamemory hypothesis are presented.

Effects of Subanesthetic Ketamine Administration on Visual and Auditory Event-Related Potentials (ERP) in Humans: A Systematic Review

Ketamine is a non-competitive N-Methyl-D-Aspartate (NMDA) receptor antagonist whose effect in subanesthetic doses has been studied for chronic pain and mood disorders treatment. It has been proposed that ketamine could change the perception of nociceptive stimuli by modulating the cortical connectivity and altering the top-down mechanisms that control conscious pain perception. As this is a strictly central effect, it would be relevant to provide fresh insight into ketamines effect on cortical response to external stimuli. Event-related potentials (ERPs) reflect the combined synchronic activity of postsynaptic potentials of many cortical pyramidal neurons similarly oriented, being a well-established technique to study cortical responses to sensory input. Therefore, the aim of this study was to examine the current evidence of subanesthetic ketamine doses on patterns of cortical activity based on ERPs in healthy subjects. To answer the question whether ERPs could be potential markers of the cortical effects of ketamine, we conducted a systematic review of ketamines effect on ERPs after single and repeated doses. We have searched PubMed, EMBASE and Cochrane Databases and pre-selected 141 articles, 18 of which met the inclusion criteria. Our findings suggest that after ketamine administration some ERP parameters are reduced (reduced N2, P2, and P3 amplitudes, PN and MMN) while others remain stable or are even increased (P50 reduction, PPI, P1, and N1 amplitudes). The current understanding of these effects is that ketamine alters the perceived contrast between distinct visual and auditory stimuli. The analgesic effect of ketamine might also be influenced by a decreased affective discrimination of sensorial information, a finding from studies using ketamine as a model for schizophrenia, but that can give an important hint not only for the treatment of mood disorders, but also to treat pain and ketamine abuse.

Distinct aspects of pain catastrophizing according to chronic pain syndromes

Introduction: Catastrophizing is the tendency to magnify the threat value of pain and has been associated with measures of physical and psychological disability among individuals with several pain conditions. The aim of this study was to investigate whether pain catastrophizing is differentially associated with distinct pain syndromes. Methods: This is a cross-sectional study including 158 patients (40 with fibromyalgia, 25 with myofascial pain syndrome, 33 with chronic tensional type headache, 33 with endometriosis, and 27 with knee osteoarthritis) and 93 healthy subjects. The recruitment procedure occurred in concurrence with randomized controlled trials. Participants answered the following instruments: Brazilian Portuguese Pain-Catastrophizing Scale, Beck Depression Inventory II, State-Trait Anxiety Inventory, Pittsburgh Sleep Quality Index, visual analogue scale for pain, as well as a sociodemographic questionnaire. Results: For the total pain catastrophizing score, patients with endometriosis had significantly more catastrophizing thoughts than knee osteoarthritis (p < 0.05). Healthy participants had lower scores than any clinical group. More interestingly were the dimensions of pain catastrophizing, which showed significant differences in more than two groups, especially magnification scores, since these scores were able to discriminate, in a particular way, the majority of clinical samples from each other. We also observed differences between rumination, magnification and helplessness scores in all groups, suggesting that the characteristics of pain catastrophizing are distinct according to the pain disorder. Conclusions: The results suggest that dimensions of pain catastrophizing differ between pain syndromes. Therefore, it is important that researchers and clinicians focus on cognitive and emotional aspects of pain perception to have more successful interventions. Keywords: Chronic pain; catastrophizing; cross-sectional study

Insights About the Neuroplasticity State on the Effect of Intramuscular Electrical Stimulation in Pain and Disability Associated With Chronic Myofascial Pain Syndrome (MPS): A Double-Blind, Randomized, Sham-Controlled Trial

Background: There is limited evidence concerning the effect of intramuscular electrical stimulation (EIMS) on the neural mechanisms of pain and disability associated with chronic Myofascial Pain Syndrome (MPS). Objectives: To provide new insights into the EIMS long-term effect on pain and disability related to chronic MPS (primary outcomes). To assess if the neuroplasticity state at baseline could predict the long-term impact of EIMS on disability due to MPS we examined the relationship between the serum brain-derived-neurotrophic-factor (BDNF) and by motor evoked potential (MEP). Also, we evaluated if the EIMS could improve the descending pain modulatory system (DPMS) and the cortical excitability measured by transcranial magnetic stimulation (TMS) parameters. Methods: We included 24 right-handed female with chronic MPS, 19–65 years old. They were randomically allocated to receive ten sessions of EIMS, 2 Hz at the cervical paraspinal region or a sham intervention (n = 12). Results: A mixed model analysis of variance revealed that EIMS decreased daily pain scores by -73.02% [95% confidence interval (CI) = -95.28 to -52.30] and disability due to pain -43.19 (95%CI, -57.23 to -29.39) at 3 months of follow up. The relative risk for using analgesics was 2.95 (95% CI, 1.36 to 6.30) in the sham group. In the EIMS and sham, the change on the Numerical Pain Scale (NPS0-10) throughout CPM-task was -2.04 (0.79) vs. -0.94 (1.18), respectively, (P = 0.01). EIMS reduced the MEP -28.79 (-53.44 to -4.15), while improved DPMS and intracortical inhibition. The MEP amplitude before treatment [(Beta = -0.61, (-0.58 to -0.26)] and a more significant change from pre- to post-treatment on serum BDNF) (Beta = 0.67; CI95% = 0.07 to 1.26) were predictors to EIMS effect on pain and disability due to pain. Conclusion: These findings suggest that a bottom–up effect induced by the EIMS reduced the analgesic use, improved pain, and disability due to chronic MPS. This effect might be mediated by an enhancing of corticospinal inhibition as seen by an increase in IC and a decrease in MEP amplitude. Likewise, the MEP amplitude before treatment and the changes induced by the EIMS in the serum BDNF predicted it’s long-term clinical impact on pain and disability due MPS. The trial is recorded in ClinicalTrials.gov: NCT02381171.

Memory monitoring and control in young and intermediate-age adults

The way adults perceive and regulate learning (metamemory) is an important indicator of how they perform on memory tasks. This study assessed memory monitoring, control and performance in young and intermediate-age adults according to item type (with or without semantic relation), type of judgment of learning (JOL - immediate or delayed), and age. Twenty-six young adults (M = 22 years old) and 18 intermediate-age adults (M = 47 years old) participated, who responded to an experimental paradigm to evaluate metamemory. Results showed that related word-pairs received higher magnitude for the JOLs and better cued-recall scores. JOLs’ accuracy was similar between the age groups, delayed JOLs being more accurate only for young adults. Intermediate-age adults apparently based their allocation of study time less on JOLs or cued-recall than young adults.

Metamemory experimental task to evaluate memory monitoring and control

Experimental tasks for the assessment of monitoring and control memory processes allow the online exam of these abilities. In the national field these tasks still need to be elaborated in order to facilitate and stimulate future research projects. This article presents the steps for the elaboration of a task for examining memory monitoring and control processes. In Study 1 we describe the selection of 100 stimuli (cue-target word pairs) and its psycholinguistic aspects. Study 2 presents data of a pilot-study of the task with ten adults, focusing on the evaluation of monitoring processes. In Study 3 we show data of monitoring and control processes of a pilot-study with 12 undergraduate students as well as a clinical case of stroke and two neurologically unimpaired elderly people. Results suggest the need of two different versions of the task for different populations, which would allow enough variance within and between participants. In addition, other preliminary findings relevant for current metamemory hypothesis are presented.

Tarea experimental de metamemoria para evaluar monitoreo y control de memoria

Experimental tasks for the assessment of monitoring and control memory processes allow the online exam of these abilities. In the national field these tasks still need to be elaborated in order to facilitate and stimulate future research projects. This article presents the steps for the elaboration of a task for examining memory monitoring and control processes. In Study 1 we describe the selection of 100 stimuli (cue-target word pairs) and its psycholinguistic aspects. Study 2 presents data of a pilot-study of the task with ten adults, focusing on the evaluation of monitoring processes. In Study 3 we show data of monitoring and control processes of a pilot-study with 12 undergraduate students as well as a clinical case of stroke and two neurologically unimpaired elderly people. Results suggest the need of two different versions of the task for different populations, which would allow enough variance within and between participants. In addition, other preliminary findings relevant for current metamemory hypothesis are presented.