Silmar Teixeira

The dopaminergic system dynamic in the time perception: A review of the evidence

ABSTRACT Dopaminergic system plays a key role in perception, which is an important executive function of the brain. Modulation in dopaminergic system forms an important biochemical underpinning of neural mechanisms of time perception in a very wide range, from milliseconds to seconds to longer daily rhythms. Distinct types of temporal experience are poorly understood, and the relationship between processing of different intervals by the brain has received little attention. A comprehensive understanding of interval timing functions should be sought within a wider context of temporal processing, involving genetic aspects, pharmacological models, cognitive aspects, motor control and the neurological diseases with impaired dopaminergic system. Particularly, an unexplored question is whether the role of dopamine in interval timing can be integrated with the role of dopamine in non-interval timing temporal components. In this review, we explore a wider perspective of dopaminergic system, involving genetic polymorphisms, pharmacological models, executive functions and neurological diseases on the time perception. We conclude that the dopaminergic system has great participation in impact on time perception and neurobiological basis of the executive functions and neurological diseases.

Acute effects of neural mobilization and infrared on the mechanics of the median nerve.

[Purpose] This study analyzed the acute effects of infrared and neural mobilization on the median nerve on the range of elbow extension of the dominant limb. [Subjects and Methods] Forty participants from university, neurologically asymptomatic, 12 males and 28 females (22.8 ± 1.9u2005years), were randomly divided into four groups: Group 1 (control) rested for 25 minutes in the supine position; Group 2 received the specific neural mobilization for the median nerve; Group 3 received an application of infrared for 15 minutes on the forearm; Group 4 received the same application of infrared followed by neural mobilization. The goniometric parameters of elbow extension were evaluated after the intervention. [Results] Significant differences of extension value were observed between Group 1 and Group 3 (15.75 degrees), and between Group 1 and Group 4 (14.60 degrees), and the average higher in Group 3 (26.35 degrees). [Conclusion] This research provides new experimental evidence that NM in relation to superficial heat produces an immediate effect on elbow range of motion versus NM isolated.

Mental Fatigue Alters Cortical Activation and Psychological Responses, Impairing Performance in a Distance-Based Cycling Trial

Purpose: We sought to verify if alterations in prefrontal cortex (PFC) activation and psychological responses would play along with impairments in pacing and performance of mentally fatigued cyclists. Materials and Methods: Eight recreational cyclists performed two preliminary sessions to familiarize them with the rapid visual information processing (RVP) test, psychological scales and 20 km cycling time trial (TT20km) (session 1), as well as to perform a VO2MAX test (session 2). Thereafter, they performed a TT20km either after a RVP test (30 min) or a time-matched rest control session (session 3 and 4 in counterbalanced order). Performance and psychological responses were obtained throughout the TT20km while PFC electroencephalography (EEG) was obtained at 10 and 20 km of the TT20km and throughout the RVP test. Increases in EEG theta band power indicated a mental fatigue condition. Repeated-measures mixed models design and post-hoc effect size (ES) were used in comparisons. Results: Cyclists completed the trial ~2.7% slower in mental fatigue (34.3 ± 1.3 min) than in control (33.4 ± 1.1 min, p = 0.02, very large ES), with a lower WMEAN (224.5 ± 17.9 W vs. 240.2 ± 20.9 W, respectively; p = 0.03; extremely large ES). There was a higher EEG theta band power during RVP test (p = 0.03; extremely large ES), which remained during the TT20km (p = 0.01; extremely large ES). RPE increased steeper in mental fatigue than in control, together with isolated reductions in motivation at 2th km (p = 0.04; extremely large ES), felt arousal at the 2nd and 4th km (p = 0.01; extremely large ES), and associative thoughts to exercise at the 6th and 16th km (p = 0.02; extremely large ES) of the TT20km. Conclusions: Mentally fatigued recreational cyclists showed impaired performance, altered PFC activation and faster increase in RPE during a TT20km.

Diagonal movement of the upper limb produces greater adaptive plasticity than sagittal plane flexion in the shoulder

The motor rehabilitation is based on exercises that involve various joints and muscle groups. One such treatment method is Proprioceptive Neuromuscular Facilitation (PNF), which involves diagonal movements simulating many activities of daily living. The objective of this study was to investigate the differences between PNF and shoulder flexion movements performed without the diagonal component (i.e., only in the sagittal plane) using beta band absolute power as a measure of plasticity. The study included 30 volunteers randomized into three groups (control, PNF, and FLEX), with electroencephalographic signals captured before and after the performance of the task. The PNF group showed an increase in beta band absolute power in both hemispheres, indicating greater plasticity than that seen in the FLEX group. Therefore, PNF seems to be capable of promoting cortical adaptations that lead to the recruitment of both hemispheres, thus influencing cortical organization in more complex tasks.

Proposal for using time estimation training for the treatment of Parkinson’s disease

Studies have shown an association between time perception and the basal ganglia and cortical areas, suggesting a role for these regions in the perception of seconds, minutes, and hours. We present the hypothesis that time estimation training tasks may change the modulatory activity of dopamine in the basal ganglia and the cortical areas related to temporal perception. Through this mechanism, the estimated training time interval can promote a compensatory effect on motor and cognitive performance via a dynamic neural adaptation process. We believe that the training will develop a competition between neural pathways involved in the process of time perception, positively affecting the brain pathways related to Parkinsons disease, and thereby minimizing the cognitive and motor deficits caused by the disease.

Effortless Attention as a Biomarker for Experienced Mindfulness Practitioners.

Objective The present study aimed at comparing frontal beta power between long-term (LTM) and first-time meditators (FTM), before, during and after a meditation session. We hypothesized that LTM would present lower beta power than FTM due to lower effort of attention and awareness. Methods Twenty one participants were recruited, eleven of whom were long-term meditators. The subjects were asked to rest for 4 minutes before and after open monitoring (OM) meditation (40 minutes). Results The two-way ANOVA revealed an interaction between the group and moment factors for the Fp1 (p<0.01), F7 (p = 0.01), F3 (p<0.01), Fz (p<0.01), F4 (p<0.01), F8 (p<0.01) electrodes. Conclusion We found low power frontal beta activity for LTM during the task and this may be associated with the fact that OM is related to bottom-up pathways that are not present in FTM. Significance We hypothesized that the frontal beta power pattern may be a biomarker for LTM. It may also be related to improving an attentive state and to the efficiency of cognitive functions, as well as to the long-term experience with meditation (i.e., life-time experience and frequency of practice).

Prevalence of neurological complications associated with Zika virus in a brazilian metropolis

The aim of this paper is to study the prevalence of Zika Virus (ZIKV) and the index of its neurological complications. This is a quantitative, cross-sectional epidemiological study. Data were collected through the compulsory notification of suspected ZIKV and its neurological alterations cases. 113 suspected ZIKV cases were reported, most of them in the summer, with a higher prevalence of females and in the fourth decade of life. Among the neurological changes, 15 Guillain-Barré Syndrome cases were reported, with one registered death. As neurological manifestations, most of them started 30 days after a ZIKV infection. No case has been confirmed laboratory. It is necessary to combat the vector, mainly in the summer, to reduce ZIKV infection and its neurological complications, besides instruction to the health professionals about these complications and serological tests requests for an accurate diagnosis.

Human foreskin fibroblasts: from waste bag to important biomedical applications

Circumcision is one of the most performed surgical procedures worldwide, and it is estimated that one in three men worldwide is circumcised, which makes the preputial skin removed after surgery an abundant material for possible applications. In particular, it is possible efficiently to isolate the cells of the foreskin, with fibroblasts being the most abundant cells of the dermis and the most used in biomedical research. This work aimed to review the knowledge and obtain a broad view of the main applications of human foreskin fibroblast cell culture. A literature search was conducted, including clinical trials, preclinical basic research studies, reviews and experimental studies. Several medical and laboratory applications of human foreskin fibroblast cell culture have been described, especially when it comes to the use of human foreskin fibroblasts as feeder cells for the cultivation of human embryonic stem cells, in addition to co-culture with other cell types. The culture of foreskin fibroblasts has also been used to: obtain induced pluripotent stem cells; the diagnosis of Clostridium difficile; to test the toxicity and effect of substances on normal cells, especially the toxicity of possible antineoplastic drugs; in viral culture, mainly of the human cytomegalovirus, study of the pathogenesis of other microorganisms; varied studies of cellular physiology and cellular interactions. Fibroblasts are important for cell models for varied application cultures, demonstrating how the preputial material can be reused, making possible new applications. Level of evidence: Not applicable for this multicentre audit.

Challenges of Airway Management in EmergencySituations: A Literature Review

The management of the airways in emergency situations is considered one of the main life-saving acts [1]. According to Advanced Trauma Life Support recommendations for the management of patients with life-threatening injuries, airway protection is the first intervention [2]. Endotracheal intubation is the technique of choice because it is a fast, more frequently successful procedure and allows the use of a larger tube [1,2]. They are indications for endotracheal intubation and emergency: maintenance of airway permeability, respiratory failure unrelated to upper airway obstruction, decreased risk of aspiration of gastric contents [2]. Evidence corroborated the findings that the efficacy of bag-valve-mask use in emergencies, most emergency intubations occur in situations of cardiorespiratory arrest, the difference in the development of pneumonia due to invasive airway management in a pre-operative environment -hospital and hospital are not significant and the combination of ketamine and propofol (known as cetofol) is an alternative for etomidate in sedation for maintaining hemodynamic stability [2-11]. The objective of this study is to perform a review on the management of the airways in emergency situations.

How high level of anxiety in Panic Disorder can interfere in working memory? A computer simulation and electrophysiological investigation

Panic disorder (PD) is characterized by repeated and unexpected attacks of intense anxiety, which are not restricted to a determined situation or circumstance. The coherence function has been used to investigate the communication among brain structures through the quantitative EEG (qEEG). The objective of this study is to analyze if there is a difference in frontoparietal gamma coherence (GC) between panic disorder patients (PDP) and healthy controls (HC) during the Visual oddball paradigm; and verify if high levels of anxiety (produced by a computer simulation) affect PDPs working memory. Nine PDP (9 female with average age of 48.8, SD: 11.16) and ten HC (1 male and 9 female with average age of 38.2, SD: 13.69) were enrolled in this study. The subjects performed the visual oddball paradigm simultaneously to the EEG record before and after the presentation of computer simulation (CS). A two-way ANOVA was applied to analyze the factors Group and the Moment for each pair of electrodes separately, and another one to analyze the reaction time variable. We verified a F3-P3 GC increased after the CS movie, demonstrating the left hemisphere participation during the anxiety processing. The greater GC in HC observed in the frontal and parietal areas (P3-Pz, F4-F8 and Fp2-F4) points to the participation of these areas with the expected behavior. The greater GC in PDP for F7-F3 and F4-P4 pairs of electrodes assumes that it produces a prejudicial noise during information processing, and can be associated to interference on the communication between frontal and parietal areas. This noise during information processing is related to PD symptoms, which should be better known in order to develop effective treatment strategies.