Processes Of Functional Reorganization Research Articles

Investigating the effects of the aging brain on real tool use performance-an fMRI study.

Healthy aging affects several domains of cognitive and motor performance and is further associated with multiple structural and functional neural reorganization patterns. However, gap of knowledge exists, referring to the impact of these age-related alterations on the neural basis of tool use-an important, complex action involved in everyday life throughout the entire lifespan. The current fMRI study aims to investigate age-related changes of neural correlates involved in planning and executing a complex object manipulation task, further providing a better understanding of impaired tool use performance in apraxia patients. A balanced number of sixteen older and younger healthy adults repeatedly manipulated everyday tools in an event-related Go-No-Go fMRI paradigm. Our data indicates that the left-lateralized network, including widely distributed frontal, temporal, parietal and occipital regions, involved in tool use performance is not subjected to age-related functional reorganization processes. However, age-related changes regarding the applied strategical procedure can be detected, indicating stronger investment into the planning, preparatory phase of such an action in older participants.

Does Residential Mobility Anticipate Urban Growth? The Importance of the Local Socioeconomic Context in a European Metropolitan Region

Urban growth at different spatial scales is analysed using the assumptions that large cities have experienced sequential cycles of urbanization, suburbanization and re-urbanization that reflect complex demographic dynamics. Original approaches, quantitative methodologies and indicators are employed to support analysis of urban growth at different spatial scales. Residential mobility is considered as a proxy measure for spatial dynamics, intensity of urban expansion and socioeconomic development at local and regional scales in Mediterranean Europe. By computing the percent share of the population living in the same municipality five years before the census date in the total resident population at the census date, a spatial analysis of residential mobility and related background context allowed for the identification of specific urban cycles, outlining heterogeneous patterns of growth in the metropolitan region of Athens, Greece, over the last three decades (1981–2011). Results indicate that changes in spatial patterns of residential mobility are associated with multiple factors (directly or indirectly), dependent on demographic dynamics and economic cycles exposing (apparent or latent) variability in the socio-spatial urban structure and functional re-organization processes across larger metropolitan areas. Multiple socioeconomic transitions are identified in the study area, with short-range population movements diverging with urbanization, suburbanization and re-urbanization. Under both economic expansion and recession, spatial patterns of residential mobility reflect differential population dynamics, whose knowledge provides innovative visions for future urban cycles in Europe.

The prognosis for post-stroke aphasia

To determine risk factors and factors of favorable prognosis for regression of post-stroke aphasia in the early recovery period of ischemic stroke (IS). A cohort study was undertaken with 40 patients with different clinical forms of aphasia. The duration of study was 3-4 months of the disease. The regression of speech and non-speech cognitive impairment was assessed by the Method of a 10-point evaluation of higher mental functions. The method involves a comprehensive assessment of all mental functions with more than 90 subtests at the beginning and at the end of rehabilitation course and the calculation of the difference in the scoring of each mental function as a measure of treatment efficacy. Using logistic regression and odds ratio estimation, significance of the influence and the prognostic relationship of symptoms related to IS, and a number of biological and social factors (sex, age, and education) were studied. An independent prognostic value for the aphasia regression on the third month of disease has the severity of neurologic symptomatology (NIHSS score) for the first day of stroke (OR 3,27 95% CI 1,02-9,77) and the third month of the disease (p=0,005, OR 4,6, 95% CI [1,39-15,11]) and the decrease in daily activity assessed by the total score of the Barthel index (p=0,004, OR 3,92, 95% CI [1,01-15,21]). A number of MRI signs (localization of post-stroke changes in the left angular gyrus, frontal-temporal region and focal volume) had a significant effect on the dynamics of non-verbal cognitive impairment. Neuropsychological examination revealed a significant improvement of speech in patients with initially severe forms of aphasias, in particular, sensory and sensorimotor. A direct relationship between age and certain clinical forms of aphasia as well as a significant positive effect of duration (β=1,91, p≤0,01) and level of education (β=1,68, p≤0,007) on aphasia regression were determined. The severity of neurologic symptoms, in particular motor and sensory deficits, both in the acute and in the recovery period of the disease is one of the pathogenetic factors worsening the processes of functional reorganization of neuronal speech networks. The positive dynamics of the recovery of speech function is associated with the initial severity and clinical form of aphasia. The level and duration of education are related to factors positively affecting post-stroke neuroplasticity.

The effectiveness of Robot-Assisted Gait Training versus conventional therapy on mobility in severely disabled progressIve MultiplE sclerosis patients (RAGTIME): study protocol for a randomized controlled trial

BackgroundGait and mobility impairments affect the quality of life (QoL) of patients with progressive multiple sclerosis (MS). Robot-assisted gait training (RAGT) is an effective rehabilitative treatment but evidence of its superiority compared to other options is lacking. Furthermore, the response to rehabilitation is multidimensional, person-specific and possibly involves functional reorganization processes. The aims of this study are: (1) to test the effectiveness on gait speed, mobility, balance, fatigue and QoL of RAGT compared to conventional therapy (CT) in progressive MS and (2) to explore changes of clinical and circulating biomarkers of neural plasticity.MethodsThis will be a parallel-group, randomized controlled trial design with the assessor blinded to the group allocation of participants. Ninety-eight (49 per arm) progressive MS patients (EDSS scale 6–7) will be randomly assigned to receive twelve 2-h training sessions over a 4-week period (three sessions/week) of either: (1) RAGT intervention on a robotic-driven gait orthosis (Lokomat, Hocoma, Switzerland). The training parameters (torque of the knee and hip drives, treadmill speed, body weight support) are set during the first session and progressively adjusted during training progression or (2) individual conventional physiotherapy focusing on over-ground walking training performed with the habitual walking device. The same assessors will perform outcome measurements at four time points: baseline (before the first intervention session); intermediate (after six training sessions); end of treatment (after the completion of 12 sessions); and follow-up (after 3 months from the end of the training program). The primary outcome is gait speed, assessed by the Timed 25-Foot Walk Test. We will also assess walking endurance, balance, depression, fatigue and QoL as well as instrumental laboratory markers (muscle metabolism, cerebral venous hemodynamics, cortical activation) and circulating laboratory markers (rare circulating cell populations pro and anti-inflammatory cytokines/chemokines, growth factors, neurotrophic factors, coagulation factors, other plasma proteins suggested by transcriptomic analysis and metabolic parameters).DiscussionThe RAGT training is expected to improve mobility compared to the active control intervention in progressive MS. Unique to this study is the analysis of various potential markers of plasticity in relation with clinical outcomes.Trial registrationClinicalTrials.gov, identifier: NCT02421731. Registered on 19 January 2015 (retrospectively registered).

Neuroplasticity-Based Technologies and Interventions for Restoring Motor Functions in Multiple Sclerosis.

Motor impairments are very common in multiple sclerosis (MS), leading to a reduced Quality of Life and active participation. In the past decades, new insights into the functional reorganization processes that occur after a brain injury have been introduced. Specifically, the motor practice seems to be determinant to induce neuroplastic changes and motor recovery. More recently, these findings have been extended to multiple sclerosis, in particular, it has been hypothesized that disease progression, functional reorganization and disability are mutually related. For this reason, neuroplasticity-based technologies and interventions have been rapidly introduced in MS rehabilitation. Constraint-induced movement therapy (CIMT), robotics and virtual reality training are new rehabilitative interventions that deliver an intensive e task-specific practice, which are two critical factors associated with functional improvements and cortical reorganization. Another promising strategy for enhancing neuroplastic changes is non-invasive brain stimulation that can be used with a priming effect on motor training. The aims of this chapter are to review the evidence of neuroplastic changes in multiple sclerosis and to present technologies and interventions that have been tested in clinical trials.

Acute Cortical Transhemispheric Diaschisis after Unilateral Traumatic Brain Injury.

Focal neocortical brain injuries lead to functional alterations, which can spread beyond lesion-neighboring brain areas. The undamaged hemisphere and its associated disturbances after a unilateral lesion, so-called transhemispheric diaschisis, have been progressively disclosed over the last decades; they are strongly involved in the pathophysiology and, potentially, recovery of brain injuries. Understanding the temporal dynamics of these transhemispheric functional changes is crucial to decipher the role of the undamaged cortex in the processes of functional reorganization at different stages post-lesion. In this regard, little is known about the acute-subacute processes after 24-48 h in the brain hemisphere contralateral to injury. In the present study, we performed a controlled cortical impact to produce a unilateral traumatic brain injury (TBI) in the motor and somatosensory cortex of mice. In vitro extracellular multi-unit recordings from large neuronal populations, together with single-cell patch-clamp recordings in the cortical network contralateral to the lesion, revealed a strong, but transient, neuronal hyperactivity as early as 24-48 h post-TBI. This abnormal excitable state in the intact hemisphere was not accompanied by alterations in neuronal intrinsic properties, but it was associated with an impairment of the phasic gamma aminobutyric acid (GABA)ergic transmission and an increased expression of GABAA receptor subunits related to tonic inhibition exclusively in the contralateral hemisphere. These data unravel a series of early transhemispheric functional alterations after diffuse unilateral cortical injury, which may compensate and stabilize the disrupted brain functions. Therefore, our findings support the hypothesis that the undamaged hemisphere could play a significant role in early functional reorganization processes after a TBI.

Response: Commentary: Cortical responses to salient nociceptive and not nociceptive stimuli in vegetative and minimal conscious state.

Response: Commentary: Cortical responses to salient nociceptive and not nociceptive stimuli in vegetative and minimal conscious state.

Multiple timescales of body schema reorganization due to plastic surgery

Plastic surgery modifies the distribution of mass centers of a person’s body segments, changing his or her posture. The functional reorganization processes that lead subjects to re-integrate these body changes into a new stable body (posture) schema is poorly understood but current theories suggest the possible contribution of two components: a feedback mechanism that strongly depends on sensory input and an internal model that is relatively less dependent on sensory input and improves posture control, for example by compensating for delayed feedback. To assess the relative contributions of these two mechanisms during the functional reorganization of a posture scheme, we have conducted a longitudinal postural study in a population of healthy adults who were subject to breast plastic surgery to reduce or augment body weight. We measured participants’ orthostatic posture and ground reaction force immediately after, after 4months, and 1year after the surgery. To investigate the role of visual sensory information in the reorganization process we tested the participants with eyes open and closed. Our results indicate that participants find a new dynamical equilibrium within a few days. However, posture maintenance remains sub-optimal long after the center of masses and the resultant of ground reaction force stop changing; in some cases, for more than 4months. Furthermore, the re-adaptation process is faster and more efficient in the eyes-open than in the eyes-closed condition. These results suggest that the reorganization involves different subsystems (responsible for the biomechanical changes, the re-calibration of feedback mechanisms, and the re-adaptation of internal models), which act at different timescales.

Membrane nanotubes between peritoneal mesothelial cells: functional connectivity and crucial participation during inflammatory reactions.

Peritoneal dialysis (PD) has attained increased relevance as continuous renal replacement therapy over the past years. During this treatment, the peritoneum functions as dialysis membrane to eliminate diffusible waste products from the blood-stream. Success and efficacy of this treatment is dependent on the integrity of the peritoneal membrane. Chronic inflammatory conditions within the peritoneal cavity coincide with elevated levels of proinflammatory cytokines leading to the impairment of tissue integrity. High glucose concentrations and glucose metabolites in PD solutions contribute to structural and functional reorganization processes of the peritoneal membrane during long-term PD. The subsequent loss of ultrafiltration is causal for the treatment failure over time. It was shown that peritoneal mesothelial cells are functionally connected via Nanotubes (NTs) and that a correlation of NT-occurrence and defined pathophysiological conditions exists. Additionally, an important participation of NTs during inflammatory reactions was shown. Here, we will summarize recent developments of NT-related research and provide new insights into NT-mediated cellular interactions under physiological as well as pathophysiological conditions.

Changes in functional network centrality underlie cognitive dysfunction and physical disability in multiple sclerosis

Background: Cognitive dysfunction in multiple sclerosis (MS) has a large impact on the quality of life and is poorly understood. Objective: The aim of this study was to investigate functional network integrity in MS, and relate this to cognitive dysfunction and physical disability. Methods: Resting state fMRI scans were included of 128 MS patients and 50 controls. Eigenvector centrality mapping (ECM) was applied, a graph analysis technique that ranks the importance of brain regions based on their connectivity patterns. Significant ECM changes were related to physical disability and cognitive dysfunction. Results: In MS patients, ECM values were increased in bilateral thalamus and posterior cingulate (PCC) areas, and decreased in sensorimotor and ventral stream areas. Sensorimotor ECM decreases were related to higher EDSS (rho = −0.24, p = 0.007), while ventral stream decreases were related to poorer average cognition (rho = 0.23, p = 0.009). The thalamus displayed increased connectivity to sensorimotor and ventral stream areas. Conclusion: In MS, areas in the ventral stream and sensorimotor cortex appear to become less central in the entire functional network of the brain, which is associated with clinico-cognitive dysfunction. The thalamus, however, displays increased connectivity with these areas. These findings may aid in further elucidating the function of functional reorganization processes in MS.

Changes in NMDA-Receptor Function in the First Week Following Laser-Induced Lesions in Rat Visual Cortex

Focal brain injuries are accompanied by processes of functional reorganization that partially compensate the functional loss. In a previous study, extracellular recordings at the border of a laser-induced lesion in the visual cortex of rats showed an enhanced synaptic plasticity, which was mediated by the activity of NR2B-contaning NMDA-receptors (NMDARs) shedding light on the potential cellular mechanisms underlying this reorganization. Given the potentially important contribution of NMDARs in processes of functional reorganization, in the present study, we used the same lesion model to further investigate lesion-induced changes in function and localization of NMDARs in the vicinity of the lesion. The most important finding was a lesion-mediated functional reexpression of nonpostsynaptic, but according to our data, presynaptic or peri-/extrasynaptic NMDARs (preNMDARs), which were undetectable in age-matched (>P21) sham-operated controls. Notably, preNMDARs were able to boost both spontaneous and evoked synaptic glutamatergic transmission. At the postsynaptic site, we also disclosed an increase in the decay time constant of NMDARs mediated currents, which was accompanied by a decreased NR2A/NR2B ratio, as revealed by Western blot analysis. All together these findings provide new insights into the role of NMDARs activity during processes of functional reorganization following a focal lesion in the cerebral cortex.

EMG biofeedback and functional magnetic resonance imaging in the post-stroke rehabilitation (precise grip training)

The mechanisms of reorganization of motor systems at the poststroke patients after rehabilitation were studied using the method functional magnetic resonance imaging (fMRI). At patients after standard rehabilitation therapy, irrespective of localization of stroke, the increase in intensity of the basic activity zones in sensomotor areas and in the field of a hemisphere of a cerebellum as for paretic, so for a healthy hand was revealed. At patients after EMG biofeedback training of the precision grip the reorganization of functional motor system consists in more significant increase of intensity of activation of the basic zones only in lesioned hemisphere; expressiveness of these changes did not depend on localization of stroke. The degree of restoration of movements of hand after EMG biofeedback training was authentically above, than after a course of standard rehabilitation therapy. Thus, fMRI and the clinical analysis have shown that EMG biofeedback training of the precision grip have the goal-directed and effective influence upon processes of functional reorganization of motor systems.

Application of the Radiometry Principles to the Design of Therapeutic-Diagnostic UHF-Apparatus Using the Own Radiations from Bioobjects

Radiometry principles of construction of the therapeutic-diagnostic UHF- apparatus on the basis of effects of interaction of the high-coherent electromagnetic fields with the fields, radiated by bioobjects are represented. Searching for new methods of testing the physiological conditions of a human organism is very actual nowadays. There has been established the correlation between the bodily malfunctions and the malfunctioning of its specific cells, blood cells in particular, so that any disease while changing their condition is initiating by the same the processes of functional reorganization and appearance of relevant with them radiation spectra of such cells. In the paper (1) it is suggested to investigate the radiation spectra of live cells upon physical effects of their interaction with the external electromagnetic field of UHF-band and to execute controlling of their interaction by one or more functional parameters of the cell suspension. It is desirable to develop the new diagnostic methods in essence as a single-discipline, for instant, an uncombined radio physical one. To use the specific properties of biologically active spots (BAS), reflexogenic zones and domains at the human body (Zakhariin - Ged zone, Podshibyakin zone etc.) shows promise for this purpose as they are the sources of electromagnetic radiation in infra-low and low frequency bands (2,3), in microwave frequency band (4) and in UHF band (5,6). Considering that the said spots, domains and zones represent a non-linear biologic system (7), then at the influence of an electromagnetic wave upon the indicated domains its interaction with the own radiation of the body occurs. One of the possible consequences of such an interaction is the modulation of an incident electromagnetic wave at the frequencies radiated by the biologically active zones (spots), when the highest component of the radiated signal spectrum is of the same order with the probing (influencing) frequency. Separation of spectral components from the spectrum of reflected complex modulated wave, estimation of amplitudes of spectral components allows to judge upon the energetic of bodily metabolism, and the

Insulin-like growth factor I modifies electrophysiological properties of rat brain stem neurons.

On systemic injection, insulin-like growth factor I (IGF-I) elicits a prolonged increase in the excitability of dorsal column nuclei (DCN) cells in the brain stem as well as other target neurons within the brain. We have explored the cellular mechanisms involved in the stimulatory effects of IGF-I as well as its functional consequences. In a rat slice preparation, IGF-I induced a sustained depolarization of 2-5 mV in 81% of DCN neurons. Depolarization was accompanied with an increase in the input resistance (15%). Voltage-clamp recordings displayed that IGF-I decreased a K+-mediated A current (60%). Furthermore, IGF-I increased, in 78% of cells, the peak amplitude (25%), and rising slope (32%) of the excitatory postsynaptic potential evoked by dorsal column stimulation; in this case, a presynaptic facilitatory process appears to be involved. When anesthetized adult rats are injected in the carotid artery with IGF-I, extracellularly recorded propioceptive DCN neurons not only show increased spike activity but also an expansion of their cutaneous receptive field in 83% of DCN cells. Significantly, the increased excitability evoked by IGF-I in the DCN cells depends both in vivo and in vitro, on activation of p38 mitogen-activated protein kinase (MAPK), a Ser-kinase known to modulate K+ channel activity. We concluded that systemic IGF-I modulated the electrophysiological properties of target neurons within the brain. In turn, these changes probably contribute to functional reorganization processes such as expansion of neuronal receptive fields.