Bruna Velasques

Neurobiological Alterations Induced by Exercise and Their Impact on Depressive Disorders

Background: The impact of physical activity on brain metabolic functions has been investigated in different studies and there is growing evidence that exercise can be used as a preventive and rehabilitative intervention in the treatment of depressive disorders. However, the exact neuronal mechanisms underlying the latter phenomenon have not been clearly elucidated. The present article summarises key results derived from studies that focussed on the neurobiological impact of exercise on brain metabolic functions associated with depressive disorders. Since major depressive disorder (MDD) is a life threatening disease it is of great significance to find reliable strategies to prevent or to cure this illness. Therefore, the aim of this paper is to review (1) the physiological relationship between physical activity and depressive disorders and (2) the potential neurobiological alterations induced by exercise that might lead to the relief of mental disorders like depression. Methods: We searched electronic databases for literature concerning the relationship between exercise and depression from 1963 until 2009. Results: The data suggests an association between physical inactivity and higher levels of depressive symptoms. Properly designed studies could show that exercise training can be as effective as antidepressive medications. Conclusion: The exact mechanisms how exercise affects the brain are not fully understood and the literature lacks of well designed studies concerning the effects of exercise training on depressive disorders. But the observed antidepressant actions of exercise are strong enough that it already can be used as an alternative to current medications in the treatment of depressive disorders.

Intermittent Maximal Exercise Improves Attentional Performance Only in Physically Active Students

BACKGROUND AND AIMS Regular physical activity participation seems to be linked to brain metabolism and to be one factor responsible for different effects of high intensity exercise on cognition. Due to this, we investigated the effect of an intermittent maximal exercise intervention on a neuropsychological test requiring sustained and selective attention in a group of low and high physically active subjects. METHOD Forty six healthy students (age: M = 23.11, SD = 2.60 years) performed in a cross-over design an intermittent incremental exercise until they reached their maximal heart rate (HR Max; intervention condition) or rested for the same duration (control condition) followed by the administration of the d2-test. RESULTS A significant interaction between physical activity participation level and exercise effect on cognitive performance emerged, with only the more physically active participants improving the performance in the cognitive test after the intervention. CONCLUSION These data extend the current knowledge base by showing that a higher participation rate in physical activity may lead to neurobiological adaptations that facilitate selected cognitive processes (i.e., attention) after high exercise intensities.

Time perception distortion in neuropsychiatric and neurological disorders.

There is no sense organ specifically dedicated to time perception, as there is for other senses such as hearing and vision. However, this subjective sense of time is fundamental to our conception of reality and it creates the temporal course of events in our lives. Here, we explored neurobiological relations from the clinical perspective, examining timing ability in patients with different neurological and psychiatric conditions (e.g. Parkinsons disease, depression, bipolar disorder, anxiety disorders and schizophrenia). The neural bases of present distortions in time perception and temporal information processing still remain poorly understood. We reviewed: a) how the brain is capable of encoding time in different environments and multiple tasks, b) different models of interval timing, c) brain structures and neurotransmitters associated with time perception, d) the relationship between memory and time perception, e) neural mechanisms underlying different theories in neural and mental processes, and f) the relationship between different mental diseases and time perception. Bibliographic research was conducted based on publications over the past thirteen years written in English in the databases Scielo, Pubmed/MEDLINE, ISI Web of Knowledge. The time perceptions research are executed to evaluate time perception in mental diseases and can provide evidence for future clinical applications.

The Value of Repetitive Transcranial Magnetic Stimulation (rTMS) for the Treatment of Anxiety Disorders: An Integrative Review

Unlike for depression, only few studies are available today investigating the therapeutic effects of repetitive transcranial magnetic stimulation (rTMS) for anxiety disorders. This review aims to provide information on the current research approaches and main findings regarding the therapeutic use of rTMS in the context of various anxiety disorders. Although positive results have frequently been reported in both open and randomized controlled studies, our review of all identified studies indicates that at present no conclusive evidence of the efficacy of rTMS for the treatment for anxiety disorders is provided. Several treatment parameters have been used, making the interpretation of the results difficult. Moreover, sham-controlled research has often been unable to distinguish between response to rTMS and sham treatment. However, there is a limitation in the rTMS methods that likely impacts only the superficial cortical layers. It is not possible to directly stimulate more distant cortical areas, and also subcortical areas, relevant to the pathogenesis of anxiety disorders, though such effects in subcortical areas are thought to be indirect, via trans-synaptic connections. We thus recommend further studies to clearly determine the role of rTMS in the treatment of anxiety disorders. Key advances in combining TMS with neuroimaging technology may aid in such future developments.

The mirror neuron system in post-stroke rehabilitation.

Different treatments for stroke patients have been proposed; among them the mirror therapy and motion imagery lead to functional recovery by providing a cortical reorganization. Up today the basic concepts of the current literature on mirror neurons and the major findings regarding the use of mirror therapy and motor imagery as potential tools to promote reorganization and functional recovery in post-stroke patients. Bibliographic research was conducted based on publications over the past thirteen years written in English in the databases Scielo, Pubmed/MEDLINE, ISI Web of Knowledge. The studies showed how the interaction among vision, proprioception and motor commands promotes the recruitment of mirror neurons, thus providing cortical reorganization and functional recovery of post-stroke patients. We conclude that the experimental advances on Mirror Neurons will bring new rational therapeutic approaches to post-stroke rehabilitation.

Alzheimer's disease and implicit memory

Specific neuropsychiatric disorders, such as Alzheimers disease (AD) affect some forms of memory while leaving others relatively intact. In this review, we investigate particularities of the relationship between explicit and implicit memories in AD. It was found that implicit memory is preserved in AD, irrespective of the task used; in other words, there was not interference from explicit memory. In addition, it was verified that is possible through implicit memory compensatory strategies such as, activities of daily living (ADL) to compensate for the explicit memory deficits. In this sense, cognitive rehabilitation (CR) demonstrates reasonable results in the process of compensation of explicit memory deficits. Concluding, the decline in explicit memory suggests that both systems are functionally independent even if the other is compromised. We expect that when explicit memory system is not involved in competition with the implicit system, the final effect of learning is better, because all of the implicit memory capacity is engaged in learning and not in competition with the explicit system.

Sensorimotor integration and psychopathology: Motor control abnormalities related to psychiatric disorders

Abstract Objectives. Recent evidence is reviewed to examine relationships among sensorimotor and cognitive aspects in some important psychiatry disorders. This study reviews the theoretical models in the context of sensorimotor integration and the abnormalities reported in the most common psychiatric disorders, such as Alzheimers disease, autism spectrum disorder and squizophrenia. Methods. The bibliographical search used Pubmed/Medline, ISI Web of Knowledge, Cochrane data base and Scielo databases. The terms chosen for the search were: Alzheimers disease, AD, autism spectrum disorder, and Squizophrenia in combination with sensorimotor integration. Fifty articles published in English and were selected conducted from 1989 up to 2010. Results. We found that the sensorimotor integration process plays a relevant role in elementary mechanisms involved in occurrence of abnormalities in most common psychiatric disorders, participating in the acquisition of abilities that have as critical factor the coupling of different sensory data which will constitute the basis of elaboration of consciously goal-directed motor outputs. Whether these disorders are associated with an abnormal peripheral sensory input or defective central processing is still unclear, but some studies support a central mechanism. Conclusion. Sensorimotor integration seems to play a significant role in the disturbances of motor control, like deficits in the feedforward mechanism, typically seen in AD, autistic and squizophrenic patients.

Strength Training and Shoulder Proprioception

CONTEXT Proprioception is essential to motor control and joint stability during daily and sport activities. Recent studies demonstrated that athletes have better joint position sense (JPS) when compared with controls matched for age, suggesting that physical training could have an effect on proprioception. OBJECTIVE To evaluate the result of an 8-week strength-training program on shoulder JPS and to verify whether using training intensities that are the same or divergent for the shoulders dynamic-stabilizer muscles promote different effects on JPS. DESIGN Randomized controlled clinical trial. SETTING We evaluated JPS in a research laboratory and conducted training in a gymnasium. PATIENTS OR OTHER PARTICIPANTS A total of 90 men, right handed and asymptomatic, with no history of any type of injury or shoulder instability. INTERVENTION(S) For 8 weeks, the participants performed the strength-training program 3 sessions per week. We used 4 exercises (bench press, lat pull down, shoulder press, and seated row), with 2 sets each. MAIN OUTCOME MEASURE(S) We measured shoulder JPS acuity by calculating the absolute error. RESULTS We found an interaction between group and time. To examine the interaction, we conducted two 1-way analyses of variance comparing groups at each time. The groups did not differ at pretraining; however, a difference among groups was noted posttraining. CONCLUSIONS Strength training using exercises at the same intensity produced an improvement in JPS compared with exercises of varying intensity, suggesting that the former resulted in improvements in the sensitivity of muscle spindles and, hence, better neuromuscular control in the shoulder.

Saccadic eye movement applications for psychiatric disorders

Objective The study presented here analyzed the patterns of relationship between oculomotor performance and psychopathology, focusing on depression, bipolar disorder, schizophrenia, attention-deficit hyperactivity disorder, and anxiety disorder. Methods Scientific articles published from 1967 to 2013 in the PubMed/Medline, ISI Web of Knowledge, Cochrane, and SciELO databases were reviewed. Results Saccadic eye movement appears to be heavily involved in psychiatric diseases covered in this review via a direct mechanism. The changes seen in the execution of eye movement tasks in patients with psychopathologies of various studies confirm that eye movement is associated with the cognitive and motor system. Conclusion Saccadic eye movement changes appear to be heavily involved in the psychiatric disorders covered in this review and may be considered a possible marker of some disorders. The few existing studies that approach the topic demonstrate a need to improve the experimental paradigms, as well as the methods of analysis. Most of them report behavioral variables (latency/reaction time), though electrophysiological measures are absent.

Electrophysiological analysis of a sensorimotor integration task

The present experiment aimed at investigating electrophysiologic changes observed as beta band asymmetry, by Quantitative Electroencephalography (qEEG), when individuals performed a reaching motor task (catching a ball in free fall). The sample was composed of 23 healthy individuals, of both sexes, with ages varying between 25 and 40 years old. All the subjects were right handed. A two-way ANOVA was applied for the statistical analysis, to verify the interaction between task moment (i.e., 2s before and 2s after balls fall) and electrode (i.e., frontal, central and temporal regions). The first analysis compared electrodes placed over the somatosensory cortex. Central sites (C3-C4) were compared with temporal regions (T3-T4). The results showed a main effect for moment and position. The second analysis was focused over the premotor cortex, which was represented by the electrodes placed on the frontal sites (F3-F4 versus F7-F8), and a main effect was observed for position. Taken together, these results show a pattern of asymmetry in the somatosensory cortex, associated with a preparatory mechanism when individuals have to catch an object during free fall. With respect to task moment, after the balls fall, the asymmetry was reduced. Moreover, the difference in asymmetry between the observed regions were related to a supposed specialization of areas (i.e., temporal and central). The temporal region was associated with cognitive processes involved in the motor action (i.e., explicit knowledge). On the other hand, the central sites were related to the motor control mechanisms per se (i.e., implicit knowledge). The premotor cortex, represented by two frontal regions (i.e., F3-F4 versus F7-F8), showed a decrease on neural activity in the contralateral hemisphere (i.e., to the right hand). This result is in agreement with other experiments suggesting a participation of the frontal cortex in the planning of the apprehension task. This sensorimotor paradigm may contribute to the repertoire of tasks used to study clinical conditions such as depression, alzheimer and Parkinson diseases.