Integrative parietal cortex processes: neurological and psychiatric aspects.

For many decades the parietal cortex (PC) has been considered the key area in tasks which involve the integration of different stimuli. PC is fundamental to determine spatial sense, information navigation and integration, and is involved in several aspects of the complex motor repertoire and in neurological and psychiatric disorders. In this review, we focus on seven different aspects of PC: (i) neuroanatomy of the parietal cortex; (ii) sensory motor integration processes; iii) hand movement control: reaching, grasping, and pointing; (iv) saccadic eye movements; (v) movement observation; (vi) neurological aspects: ataxia, autism and Parkinson's disease; and (vii) psychiatric aspects: schizophrenia, bipolar disorder and depression. Among these, we related the perspectives which involve the functions of the parietal cortex and mirror neurons and that seem to play a fundamental role in action prediction, planning, observation and execution. Furthermore, we focused on the relationship between posterior parietal cortex (PPC) and hand-guided movements. For this review, we conducted an academic paper search which fulfilled the objective of the study. We conclude that the PC has great participation in different motor functions and neurological/psychiatric disorders.

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. Parkinson's 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.

Effects of Methylphenidate on performance of a practical pistol shooting task: a quantitative electroencephalography (qEEG) study.

BACKGROUND: The present study examined absolute alpha power using quantitative electroencephalogram (qEEG) in bilateral temporal and parietal cortices in novice soldiers under the influence of methylphenidate (MPH) during the preparatory aiming period in a practical pistol-shooting task. We anticipated higher bi-hemispheric cortical activation in the preparatory period relative to pre-shot baseline in the methylphenidate group when compared with the control group because methylphenidate has been shown to enhance task-related cognitive functions. METHODS: Twenty healthy, novice soldiers were equally distributed in control (CG; n = 10) and MPH groups 10 mg (MG; n = 10) using a randomized, double blind design. Subjects performed a pistol-shooting task while electroencephalographic activity was acquired. RESULTS: We found main effects for group and practice blocks on behavioral measures, and interactions between group and phases on electroencephalographic measures for the electrodes T3, T4, P3 and P4. Regarding the behavioral measures, the MPH group demonstrated significantly poorer in shooting performance when compared with the control and, in addition, significant increases in the scores over practice blocks were found on both groups. In addition, regarding the electroencephalographic data, we observed a significant increase in alpha power over practice blocks, but alpha power was significantly lower for the MPH group when compared with the placebo group. Moreover, we observed a significant decrease in alpha power in electrodes T4 and P4 during PTM. CONCLUSION: Although we found no correlation between behavioral and EEG data, our findings show that MPH did not prevent the learning of the task in healthy subjects. However, during the practice blocks (PBs) it also did not favor the performance when compared with control group performance. It seems that the CNS effects of MPH demanded an initial readjustment period of integrated operations relative to the sensorimotor system. In other words, MPH seems to provoke a period of initial instability due to a possible modulation in neural activity, which can be explained by lower levels of alpha power (i.e., higher cortical activity). However, after the end of the PB1 a new stabilization was established in neural circuits, due to repetition of the task, resulting higher cortical activity during the task. In conclusion, MPH group performance was not initially superior to that of the control group, but eventually exceeded it, albeit without achieving statistical significance.

Integración sensitivomotora: conceptos básicos, anomalías relacionadas con trastornos del movimiento y reorganización cortical inducida por el entrenamiento sensitivomotor / Sensorimotor integration: basic concepts, abnormalities related to movement disorders and sensorimotor training-induced cortical reorganization

Introducción. La integración sensitivomotora se define como la capacidad del sistema nervioso central para integrar diferentes fuentes de estímulos y, paralelamente, transformar dichas entradas en acciones motoras. Objetivos. Revisar los principios básicos de la integración sensitivomotora, como sus bases neuronales y sus mecanismos elementales implicados en tareas orientadas hacia la consecución de objetivos específicos realizadas por sujetos sanos, y las anomalías descritas en los trastornos del movimiento más frecuentes, como la enfermedad de Parkinson, la distonía y el accidente cerebrovascular, además de los mecanismos relacionados con la reorganización cortical. Desarrollo y conclusiones. Todavía no está claro si estos trastornos se asocian a una entrada sensitiva periférica anormal o a un procesamiento central defectuoso, pero la mayoría de datos respaldan un mecanismo central. Nuestros resultados muestran que el proceso de integración sensitivomotora desempeña un posible papel en los mecanismos elementales implicados en tareas orientadas hacia la consecución de objetivos específicos realizadas por sujetos sanos y en la aparición de anomalías en la mayoría de trastornos del movimiento más frecuentes; asimismo, desempeña un posible papel en la adquisición de habilidades que tienen como factor crítico el acoplamiento de diferentes datos sensitivos que constituirán la base de elaboración de entradas motoras orientadas conscientemente hacia la consecución de objetivos (AU)

Introduction. Sensorimotor integration is defined as the capability of the central nervous system to integrate different sources of stimuli, and parallelly, to transform such inputs in motor actions. Aim. To review the basic principles of sensorimotor integration, such as, its neural bases and its elementary mechanisms involved in specific goal-directed tasks performed by healthy subjects, and the abnormalities reported in the most common movement disorders, such as, Parkinson’ disease, dystonia and stroke, like the cortical reorganization-related mechanisms. Development and conclusions. Whether these disorders are associated with an abnormal peripheral sensory input or defective central processing is still unclear, but most of the data support a central mechanism. We found that the sensorimotor integration process plays a potential role in elementary mechanisms involved in specific goal-directed tasks performed by healthy subjects and in occurrence of abnormalities in most common movement disorders and, moreover, play a potential role on the acquisition of abilities that have as critical factor the coupling of different sensory data which will constitute the basis of elaboration of motor outputs consciously goal-directed (AU)

Sensorimotor integration: basic concepts, abnormalities related to movement disorders and sensorimotor training-induced cortical reorganization.

INTRODUCTION: Sensorimotor integration is defined as the capability of the central nervous system to integrate different sources of stimuli, and parallelly, to transform such inputs in motor actions. AIM: To review the basic principles of sensorimotor integration, such as, its neural bases and its elementary mechanisms involved in specific goal-directed tasks performed by healthy subjects, and the abnormalities reported in the most common movement disorders, such as, Parkinson' disease, dystonia and stroke, like the cortical reorganization-related mechanisms. DEVELOPMENT AND CONCLUSIONS: Whether these disorders are associated with an abnormal peripheral sensory input or defective central processing is still unclear, but most of the data support a central mechanism. We found that the sensorimotor integration process plays a potential role in elementary mechanisms involved in specific goal-directed tasks performed by healthy subjects and in occurrence of abnormalities in most common movement disorders and, moreover, play a potential role on the acquisition of abilities that have as critical factor the coupling of different sensory data which will constitute the basis of elaboration of motor outputs consciously goal-directed.

Gamma band oscillations under influence of bromazepam during a sensorimotor integration task: an EEG coherence study.

The goal of the present study was to explore the dynamics of the gamma band using the coherence of the quantitative electroencephalography (qEEG) in a sensorimotor integration task and the influence of the neuromodulator bromazepam on the band behavior. Our hypothesis is that the needs of the typewriting task will demand the coupling of different brain areas, and that the gamma band will promote the binding of information. It is also expected that the neuromodulator will modify this coupling. The sample was composed of 39 healthy subjects. We used a randomized double-blind design and divided subjects into three groups: placebo (n=13), bromazepam 3mg (n=13) and bromazepam 6 mg (n=13). The two-way ANOVA analysis demonstrated a main effect for the factors condition (i.e., C4-CZ electrode pair) and moment (i.e., C3-CZ, C3-C4 and C4-CZ pairs of electrodes). We propose that the gamma band plays an important role in the binding among several brain areas in complex motor tasks and that each hemisphere is influenced in a different manner by the neuromodulator.

Alzheimer's disease and implicit memory.

Specific neuropsychiatric disorders, such as Alzheimer's 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.

Alzheimer's disease and implicit memory / Doença de Alzheimer e memória implícita

Specific neuropsychiatric disorders, such as Alzheimer's 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.

Distúrbios neuropsiquiátricos específicos, tais como a doença de Alzheimer (DA), podem afetar algumas formas de memória enquanto deixam outros relativamente intactos. Nesta revisão, nós investigamos particularidades da relação entre as memórias explicita e implícita na DA. Foi verificado que a memória é preservada na DA, independente da tarefa usada; ou seja, não ocorre interferência da memória explícita. Além disso, foi verificado que é possível através de estratégias compensatórias de memória implícita, tais como, atividades da vida diária (AVD) compensar os déficits da memória explícita. Neste sentido, a reabilitação cognitiva (RC) demonstra resultados razoáveis no processo de compensação dos déficits da memória explicita. Concluindo, a queda na memória explícita sugere que ambos os sistemas são funcionalmente independentes mesmo que outro esteja comprometido. Esperamos que quando o sistema de memória explícita não está envolvido em competição com o sistema implícito, o efeito final de aprendizagem é melhor, porque toda a capacidade da memória implícita está engajada na aprendizagem e não na competição com o sistema explícito.

Changes in slow and fast alpha bands in subjects submitted to different amounts of functional electrostimulation.

OBJECTIVE: To examine the changes in slow (8-10Hz) and fast (10-12Hz) alpha bands of EEG in three groups of subjects submitted to different amounts of functional electrostimulation (FES). Our hypothesis is that different amounts of electrostimulation may cause different patterns of activation in the sensorimotor cortex. In particular, we expect to see an increase in alpha power due to habituation effects. We examine the two bands comprised by alpha rhythm (i.e., slow and fast alpha), since these two sub-rhythms are related to distinct aspects: general energy demands and specific motor aspects, respectively. METHODS: The sample was composed of 27 students, both sexes, aging between 25 and 40 years old. The subjects were randomly distributed in three groups: control (n=9), G24 (n=9) and G36 (n=9). A FES equipment (Neuro Compact-2462) was used to stimulate the right index finger extension. Simultaneously, the electroencephalographic signal was acquired. We investigated the absolute power in slow and fast alpha bands in the sensorimotor cortex. RESULTS: The G36 indicated a significant increasing in absolute power values in lower and higher alpha components, respectively, when compared with the control group. Particularly, in the following regions: pre-motor cortex and primary motor cortex. DISCUSSION: FES seems to promote cortical adaptations that are similar to those observed when someone learns a procedural task. FES application in the G36 was more effective in promoting such neural changes. The lower and higher components of alpha rhythms behave differently in their topographical distribution during FES application. These results suggest a somatotopic organization in primary motor cortex which can be represented by the fast alpha component.

Therapeutic applications of repetitive transcranial magnetic stimulation in clinical neurorehabilitation.

Transcranial magnetic stimulation (TMS) was introduced nearly 20 years ago and has since been developed as a sophisticated tool for neuroscience research. It is an excellent technique that complements other non-invasive methods for studying human brain physiology. The aim of the present study was to review the basic concepts and principles of the repetitive TMS (rTMS) technique, gathering evidence of its applications in neurorehabilitation. Several clinical studies have reported that sessions of rTMS can improve some or all of the motor symptoms associated with Parkinson's disease, dystonia and stroke. However, since these changes are transient, it is premature to propose these applications as realistic therapeutic options, even though the rTMS technique has shown itself to be, potentially, a modulator of sensorimotor integration and neurogenesis. Future work in this area promises to advance our understanding of the pathophysiology of a wide range of neurological conditions, generate widely applicable diagnostic tools for clinical neurophysiology, and perhaps establish neuromodulation as a viable therapeutic option in neurorehabilitation.