Ability Of Central Nervous System Research Articles

Retinal Plasticity

Brain plasticity is a well-established concept designating the ability of central nervous system (CNS) neurons to rearrange as a result of learning, when adapting to changeable environmental conditions or else while reacting to injurious factors. As a part of the CNS, the retina has been repeatedly probed for its possible ability to respond plastically to a variably altered environment or to pathological insults. However, numerous studies support the conclusion that the retina, outside the developmental stage, is endowed with only limited plasticity, exhibiting, instead, a remarkable ability to maintain a stable architectural and functional organization. Reviewed here are representative examples of hippocampal and cortical paradigms of plasticity and of retinal structural rearrangements found in organization and circuitry following altered developmental conditions or occurrence of genetic diseases leading to neuronal degeneration. The variable rate of plastic changes found in mammalian retinal neurons in different circumstances is discussed, focusing on structural plasticity. The likely adaptive value of maintaining a low level of plasticity in an organ subserving a sensory modality that is dominant for the human species and that requires elevated fidelity is discussed.

Fatigue, induced via repetitive upper-limb motor tasks, influences trunk and shoulder kinematics during an upper limb reaching task in a virtual reality environment.

BackgroundEfficient shoulder movement depends on the ability of central nervous system to integrate sensory information and to create an appropriate motor command. Various daily encountered factors can potentially compromise the execution of the command, such as fatigue. This study explored how fatigue influences shoulder movements during upper limb reaching.MethodsForty healthy participants were randomly assigned to one of two groups: Control or Fatigue Group. All participants completed an upper limb reaching task at baseline and post-experimental, during which they reached four targets located at 90° of shoulder abduction, 90° external rotation at 90° abduction, 120° scaption, and 120° flexion in a virtual reality environment. Following the baseline phase, the Fatigue Group completed a shoulder fatigue protocol, while Controls took a 10-minute break. Thereafter, the reaching task was repeated. Upper limb kinematic (joint angles and excursions) and spatiotemporal (speed and accuracy) data were collected during the reaching task. Electromyographic activity of the anterior and middle deltoids were also collected to characterize fatigue. Two-way repeated-measures ANOVA were performed to determine the effects of Time, Group and of the interaction between these factors.ResultsThe Fatigue group showed decreased mean median power frequency and increased electromyographic amplitudes of the anterior deltoid (p < 0.05) following the fatigue protocol. Less glenohumeral elevation, increased trunk flexion and rotation and sternoclavicular elevation were also observed in the Fatigue group (Group x Time interaction, p < 0.05). The Control group improved their movement speed and accuracy in post-experimental phase, while the Fatigue group showed a decrease of movement speed and no accuracy improvement (Group x Time interaction, p < 0.05).ConclusionIn a fatigued state, changes in movement strategy were observed during the reaching task, including increased trunk and sternoclavicular movements and less glenohumeral movement. Performance was altered as shown by the lack of accuracy improvement over time and a decrease in movement speed in the Fatigue group.

Study of effects of yoga and pranayama on human reaction time and certain physiological parameters in normal and hypertensive subjects

Background: Yoga is a process of gaining control over the mind, as defined by Patanjali. Stress has been implicated as one of the major causes of essential hypertension. Yoga works on every cell of the body. Yoga influences body as well as controls the stress in the individual. An index of the processing ability of central nervous system and a simple means of determining sensory-motor performance is referred to as reaction time (RT). It has been proclaimed that human performance including central neural processing is improved by yoga training. It improves cardiorespiratory performance, balances autonomic nervous system, decreases pulse, respiratory rate, systolic and diastolic blood pressure. Aims and Objective: To show the effects of yoga and pranayam on auditory and visual RT and on certain physiological parameters such as weight, body mass index, pulse rate, respiratory rate, systolic blood pressure, and diastolic blood pressure in normal and hypertensive subjects. Materials and Methods: This comparative type of study included 70 normal and 70 hypertensive subjects. It was carried on subjects between 30 and 60 years of age. Auditory reaction time (ART) and visual reaction time (VRT) were studied in subjects with “Response Analyzer” reaction time apparatus. The physiological parameters such as weight, body mass index, pulse rate, respiratory rate, systolic blood pressure, and diastolic blood pressure were measured. Parameters were measured in two sittings; on admission to yoga center and after 3 months. Statistical software STATA Version 10.0 was used for statistical analysis. Result: It was found that changes in the RT and physiological parameters were significant in hypertensive subjects when compared with normal individuals. Conclusion: Yoga is a helpful intervention in hypertensive subjects. Yoga and pranayam are more beneficial to hypertensive subjects. RT is an index of cortical arousal, and a decrease in it indicates an improved sensory-motor performance and an enhanced processing ability of the central nervous system.

Psychomotor Retardation, Attention Deficit and Executive Dysfunctional in Young Non-hospitalised Un-medicated Non- psychotic Unipolar Depression Patients

Neuropsychological deficits have been reported in patients with Major Depressive Disorder (MDD) during an acute episode. The reaction time gives an idea about integrity and the processing ability of central nervous system. The simple reaction time task is an attention seeking task that focuses primarily on speed of processing (executive function). Psychomotor retardation (i.e., delay at the output which includes perceptual decision, planning, motor process) is a constant and probably central feature of depression. The purpose of present study was to evaluate the neuropsychological functioning in young non-hospitalised un-medicated non-psychotic unipolar depression by focusing on tasks related to prefrontal cortex functioning. Newly diagnosed young antidepressant-free, clinically depressed patients (20 males and 24 females, n=44) and healthy controls (24 males and 27 females, n=51) pair-wise matched on gender, age (mean age 25±4) were included in this study. All patients were diagnosed with major depressive episode according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Both the patients and healthy controls performed a simple reaction time task with components of alerting auditory and visual orientation of attention by an instrument response analyzer. Statistical Analysis : The performances were expressed in mean ± standard deviation of the reaction time by using the Student's unpaired t-test. Patients with unipolar depression relative to controls were impaired on psychomotor performance and deficits in sustained attention remained significant. These findings suggest deficits in sustained attention as vulnerability marker for unipolar depression. With further methodologically sound research, the changes in neuropsychological function associated with treatment response may provide a means of evaluating different treatment strategies in major depression.

Regulation of axonal regeneration following the central nervous system injury in adult mammalian

It has been well established that the recovery ability of central nervous system (CNS) is very poor in adult mammals. As a result, CNS trauma generally leads to severe and persistent functional deficits. Thus, the investigation in this field becomes a "hot spot". Up to date, accumulating evidence supports the hypothesis that the failure of CNS neurons to regenerate is not due to their intrinsic inability to grow new axons, but due to their growth state and due to lack of a permissive growth environment. Therefore, any successful approaches to facilitate the regeneration of injured CNS axons will likely include multiple steps: keeping neurons alive in a certain growth-state, preventing the formation of a glial scar, overcoming inhibitory molecules present in the myelin debris, and giving direction to the growing axons. This brief review focused on the recent progress in the neuron regeneration of CNS in adult mammals.

Effect Of Exercise In The Heat On The Hormonal Response To An Insulin Challenge

Exercise in hot ambient severely disrupts body homeostasis and enhances autonomic and neuroendocrine responses to exercise. Also, high levels of exercise-induced hyperthermia seem to be able to affect cerebral electrical activity and the ability of central nervous system to recruit the skeletal muscles. Thus, it is possible that exercise in the heat also induces subtle changes in the central pathways that regulate hypothalamic function that may be revealed by a subsequent metabolic challenge. PURPOSE To determine the effect of exhausting exercise in the heat on cardiovascular and neuroendocrine responses to an acute hypoglycemic insulin challenge (IC) conducted after exercise. METHODS Twelve active males underwent a hypoglycemic insulin challenge (0.15 mIU/kg) 2.5 h after 60 min of cycle exercise (E)(60% peak power) in the heat (35°C; 20% rh) or after rest (R). Blood samples were taken during IC to measure plasma glucose (GLU), lactate (LAC), prolactin (PRL) and cortisol (CORT). Heart rate (HR) and mean blood pressure (MBP) were obtained by ECG recording and automated sphygmomanometer, respectively. Trial comparisons were made using twoway ANOVA with repeated measures. RESULTS Rectal temperature rose from 36.98 ±0.08°C at rest to 38.35 ±0.11°C at the end of exercise (p<0.001) and at this point RPE scores attained 16.5 ±0.8 units. GLU during IC reached similar nadirs in both trials with values below 2.2 mmol/L. Plasma LAC during IC increased above baseline to a similar extent in both trials, with peak values of 2.33 ±0.20 mmol/L and 2.65 ±0.26 mmol/L in E and R, respectively. At IC onset, plasma PRL and CORT had recover from levels at the end of exercise in the heat to baseline levels. Peak values of plasma PRO and CORT during IC were unchanged by prior exercise and amounted to around 5- and 2.5-fold baseline levels, respectively. HR and MBP had a similar biphasic change in the two trials, increasing during the first hour post insulin injection and declining to below baseline levels thereafter. CONCLUSION Exhaustive exercise in the heat does not induce acute changes in heart rate, blood pressure and hormonal reactivity to a hypoglycemic challenge, revealing hypothalamic and pituitary robustness to the effects of acute exercise in the heat. Partially supported by EU and Portuguese government grant PRAXIS XXI BD/21295/99.

Effect Of Exercise In The Heat On The Hormonal Response To An Insulin Challenge

Exercise in hot ambient severely disrupts body homeostasis and enhances autonomic and neuroendocrine responses to exercise. Also, high levels of exercise-induced hyperthermia seem to be able to affect cerebral electrical activity and the ability of central nervous system to recruit the skeletal muscles. Thus, it is possible that exercise in the heat also induces subtle changes in the central pathways that regulate hypothalamic function that may be revealed by a subsequent metabolic challenge. PURPOSE To determine the effect of exhausting exercise in the heat on cardiovascular and neuroendocrine responses to an acute hypoglycemic insulin challenge (IC) conducted after exercise. METHODS Twelve active males underwent a hypoglycemic insulin challenge (0.15 mIU/kg) 2.5 h after 60 min of cycle exercise (E)(60% peak power) in the heat (35°C; 20% rh) or after rest (R). Blood samples were taken during IC to measure plasma glucose (GLU), lactate (LAC), prolactin (PRL) and cortisol (CORT). Heart rate (HR) and mean blood pressure (MBP) were obtained by ECG recording and automated sphygmomanometer, respectively. Trial comparisons were made using twoway ANOVA with repeated measures. RESULTS Rectal temperature rose from 36.98 ±0.08°C at rest to 38.35 ±0.11°C at the end of exercise (p<0.001) and at this point RPE scores attained 16.5 ±0.8 units. GLU during IC reached similar nadirs in both trials with values below 2.2 mmol/L. Plasma LAC during IC increased above baseline to a similar extent in both trials, with peak values of 2.33 ±0.20 mmol/L and 2.65 ±0.26 mmol/L in E and R, respectively. At IC onset, plasma PRL and CORT had recover from levels at the end of exercise in the heat to baseline levels. Peak values of plasma PRO and CORT during IC were unchanged by prior exercise and amounted to around 5- and 2.5-fold baseline levels, respectively. HR and MBP had a similar biphasic change in the two trials, increasing during the first hour post insulin injection and declining to below baseline levels thereafter. CONCLUSION Exhaustive exercise in the heat does not induce acute changes in heart rate, blood pressure and hormonal reactivity to a hypoglycemic challenge, revealing hypothalamic and pituitary robustness to the effects of acute exercise in the heat. Partially supported by EU and Portuguese government grant PRAXIS XXI BD/21295/99.

The use of schwann cell transplantation to foster central nervous system repair

Schwann cells (SCs) have been a key element in the demonstration of the ability of central nervous system (CNS) neurons to regenerate when provided with an appropriate environment. SCs transplanted into injured adult mammalian CNS (including the optic and septo-hippocampal systems, spinal cord and diencephalon) survive, promote axonal regeneration, and ensheathe or myelinate the regenerated axons. Methods to graft SCs into the lesioned CNS range from injection of a SC suspension to transplantation of more elaborate SC constructs using polymeric bridges. We discuss in detail the use of semipermeable guidance channels seeded with purified populations of SCs. These studies suggest that the ability of SCs to function in various injured CNS regions might lead to new avenues for the treatment of CNS injuries and demyelinating conditions in the human.

Tensor network theory of the metaorganization of functional geometries in the central nervous system

Here we present an elaboration and a quantitative example for a hypothetical neuronal process, implementing what we refer to as the metaorganization principle. This process allows the internalization of external (body) geometries into the central nervous System (CNS) and a reciprocal and equally important action of the CNS geometry on the external (body) geometry. The hypothesis is based on the distinction, within the CNS, between covariant sensory and contravariant motor vectorial expressions of the extrinsic geometry. These sensory and motor expressions, given in natural co-ordinate Systems, are transformed from one to the other by a neuronal network which acts as a metric tensor. The metric tensor determines the relationship of these two expressions and thus comprises the functional geometry of the System. The emergence through metaorganization of networks that implement such metric function is viewed as the result of interactions between the covariant motor execution which generates a physical action on the external world (via the musculoskeletal System) and the covariant sensory proprioception which measures the effect of such motor output. In this transformation of contravariants to covariants by the physical geometry of the motor System, a covariant metric tensor is expressed implicitly. However, co-ordinated motor action requires its dual tensor (the contravariant metric) which is assembled in the CNS based on the metaorganization principle, i.e. the ability of CNS and external geometries to mold one another. The two metric transformations acting on each other detect error signais whenever the match of the physical and functional geometries is imperfect. Such error signals are utilized by the metaorganization process to improve the match between the two metrics, so that with use the internal representation becomes increasingly homeometric with the geometry of the external world. The proposed physical process by which the metaorganization principle is implemented is based on oscillatory reverberation. If covariant proprioception is used as a recurrent signal to the motor apparatus, as if it were a contravariant motor expression, then reverberations at their steady-state yield the eigenvectors and eigenvalues of the System. The stored eigenvectors and eigenvalues can serve, respectively, (1) as a means for the genesis of a metric (in the form of its spectral representation) with the given eigenvectors and (2) as a means of comparing the eigenvalues that are implicit in the external body geometry and those of the internal metric. The difference between these eigenvalues is then used to modify the metric so that it “evolves” to perform a more accurate covariant-contravariant transformation. The metric can be represented by the dyadic outer products of its eigenvectors where each dyad is weighted by the corresponding eigenvalue. Such a spectral representation yields in a uniform manner (a) the contravariant metric (in the case of complete CNS hyperspaces) and (b) the Moore-Penrose generalized inverse of the covariant metric tensor (in the case of non-Riemannian overcomplete CNS hyperspaces). The metaorganization of metric networks, together with the sensorimotor covariant embedding network, provides an explanation of the emergence of a whole sensorimotor apparatus leading to the feasibility of constructing truly brain-like robotic Systems.

Detection of neuronal tissue from brain grafts with anti-Thy-1.1 antibody.

Grafting of neural tissue has been used to investigate the ability of central nervous system (CNS) axons to elongate into peripheral nerve grafts; to investigate the growth characteristics of material transplanted within the CNS; and to determine if grafts producing amines or peptides can replace a natural or experimentally induced depletion of these biogenic molecules. In such experiments donor tissue has been distinguished from host by injection into graft cells of horseradish peroxidase or radioactive leucine or by detecting biogenic molecules in the grafted tissue with antibodies. All these methods have limitations and a technique which allows identification of the total neuronal cell output from transplanted tissue would be a powerful tool in delineating host-graft interactions. Polymorphic cell-surface antigens have not previously been exploited as markers. The Thy-1 antigen is an abundant glycoprotein of neurones and in the mouse exists in two allotypic forms called Thy-1.1 and Thy-1.2. We now show that tissue from Thy-1.1-positive animals grafted into Thy-1.1-negative brains can be clearly identified in cryostat sections using an anti-Thy-1.1 monoclonal antibody conjugated with peroxidase. We have used the method to study grafts from normal fetal mice which correct a developmental deficiency when transplanted into hpg mutant mice.