[The life quality of the disabled as a result of diseases of peripheral nervous system].

The article considers results of studying the quality of life of disabled patients because of diseases of peripheral nervous system. The significantly low level of indices of quality of life self-assessment was established on all scales of SF-36 questionnaire that are from 3 to 7 times lower than similar indices in population of Russia. The assessment of quality of life of disabled patients is necessary to determine effectiveness of applied rehabilitation measures and application of obtained results in planning further rehabilitation and habilitation activities.

[The social economic aspects of disability resulted from diseases of peripheral nervous system].

The diseases of peripheral nervous system (PNS diseases) are diagnosed in 48%-72% of workers in various branches of economy. They made up more than half of all occupational diseases and are the main cause of labor ability and of high level of disability able-bodied population. The purpose of the study is to assess social economic importance of disability because of PNS diseases of able-bodied population in the Republic of Bashkortostan. It is established that in 2014-2018 about 107 individuals of able-bodied age for the first time became disabled because of PNS diseases. The average annual level of individuals of able-bodied age with for the first time established disabilities because of PNS diseases made up to 0.1 cases per 10 thousand of population. Among the disabled 69.0 ± 5.4% are males. The disability rate in males (0.142o/ooo) is twice higher than in females (0.063o/ooo). The average age of the disabled is 48.7 ± 5.7 years. In the structure of disability dominate lumbosacral radiculopathy (50.9%), polyneuropathy of upper (15.3%) and lower (13.5%) extremities. In average, the disability develops in 11.3 years prior to age of 60 years and on 3.8-5.5 years earlier than in case of other diseases. The disability because of PNS diseases shortens healthy life expectancy by 16.0% in males and by 17.8% in females. Annual economic losses come to more than 26 million rubles of non-produced production. The disability because of PNS consists significant social economic problem of society and requires increased attention to prevention, early diagnostics, treatment, improvement of quality of medical social expertise, rehabilitation and habilitation.

Transfer effects of training-induced visual field recovery in patients with chronic stroke.

OBJECTIVE: Visual training of light detection in the transition zone between blind and healthy hemianopic visual fields leads to improvement of color and simple pattern recognition. Recently, we demonstrated that visual field enlargement (VFE) also occurs when an area just beyond the transition zone is stimulated. In the current study, we attempted to determine whether this peripheral training also causes improvement in color and shape perception and reading speed. Further, we evaluated which measure of VFE relates best to improvements in performance: the average border shift (ABS) in degrees or the estimated amount of cortical surface gain (ECSG) in millimeters, using the cortical magnification factor (CMF). METHOD: Twelve patients received 40 sessions of 1-hour restorative function training (RFT). Before and after training, we measured visual fields and reading speed. Additionally, color and shape perception in the trained visual field area was measured in 7 patients. RESULTS: VFE was found for 9 of 12 patients. Significant improvements were observed in reading speed for 8 of 12 patients and in color and shape perception for 3 of 7 patients. ECSG correlates significantly with performance; ABS does not. Our data indicate that the threshold ECSG, needed for significant changes in color and shape perception and reading speed, is about 6 mm. CONCLUSIONS: White stimulus training-induced VFE can lead to improved color and shape perception and to increased reading speed in and beyond the pretraining transition zone if ECSG is sufficiently large. The latter depends on the eccentricity of the VFE.

Effects of vision restoration training on early visual cortex in patients with cerebral blindness investigated with functional magnetic resonance imaging.

Cerebral blindness is a loss of vision as a result of postchiasmatic damage to the visual pathways. Parts of the lost visual field can be restored through training. However, the neuronal mechanisms through which training effects occur are still unclear. We therefore assessed training-induced changes in brain function in eight patients with cerebral blindness. Visual fields were measured with perimetry and retinotopic maps were acquired with functional magnetic resonance imaging (fMRI) before and after vision restoration training. We assessed differences in hemodynamic responses between sessions that represented changes in amplitudes of neural responses and changes in receptive field locations and sizes. Perimetry results showed highly varied visual field recovery with shifts of the central visual field border ranging between 1 and 7°. fMRI results showed that, although retinotopic maps were mostly stable over sessions, there was a small shift of receptive field locations toward a higher eccentricity after training in addition to increases in receptive field sizes. In patients with bilateral brain activation, these effects were stronger in the affected than in the intact hemisphere. Changes in receptive field size and location could account for limited visual field recovery (± 1°), although it could not account for the large increases in visual field size that were observed in some patients. Furthermore, the retinotopic maps strongly matched perimetry measurements before training. These results are taken to indicate that local visual field enlargements are caused by receptive field changes in early visual cortex, whereas large-scale improvement cannot be explained by this mechanism.

Functional MRI of visual cortex predicts training-induced recovery in stroke patients with homonymous visual field defects.

Post-chiasmatic damage to the visual system leads to homonymous visual field defects (HVDs), which can severely interfere with daily life activities. Visual Restitution Training (VRT) can recover parts of the affected visual field in patients with chronic HVDs, but training outcome is variable. An untested hypothesis suggests that training potential may be largest in regions with 'neural reserve', where cortical responses to visual stimulation do not lead to visual awareness as assessed by Humphrey perimetry-a standard behavioural visual field test. Here, we tested this hypothesis in a sample of twenty-seven hemianopic stroke patients, who participated in an assiduous 80-hour VRT program. For each patient, we collected Humphrey perimetry and wide-field fMRI-based retinotopic mapping data prior to training. In addition, we used Goal Attainment Scaling to assess whether personal activities in daily living improved. After training, we assessed with a second Humphrey perimetry measurement whether the visual field was improved and evaluated which personal goals were attained. Confirming the hypothesis, we found significantly larger improvements of visual sensitivity at field locations with neural reserve. These visual field improvements implicated both regions in primary visual cortex and higher order visual areas. In addition, improvement in daily life activities correlated with the extent of visual field enlargement. Our findings are an important step toward understanding the mechanisms of visual restitution as well as predicting training efficacy in stroke patients with chronic hemianopia.

Impact of early feeding on childhood eczema: development after nutritional intervention compared with the natural course - the GINIplus study up to the age of 6 years.

BACKGROUND: Nutritional intervention with hydrolysed infant formulas has been shown efficacious in preventing eczema in children predisposed to allergy. However, this preventive effect has never been related to the natural course of eczema in children with or without a family history of allergy. The aim of this study therefore was to compare the course of eczema in predisposed children after nutritional intervention to the natural course of eczema. METHOD: The prospective German birth cohort study GINIplus includes a total of 5991 children, subdivided into interventional and non-interventional groups. Children with a familial predisposition for allergy whose parents agreed to participate in the prospective, double-blind intervention trial (N=2252) were randomly assigned at birth to one of four formulas: partially or extensively hydrolysed whey, extensively hydrolysed casein (eHF-C) or standard cow's milk formula. Children with or without familial predisposition represented the non-interventional group (N=3739). Follow-up data were taken from yearly self-administered questionnaires from 1 up to 6 years. The outcome was physician-diagnosed eczema and its symptoms. The cumulative incidence of eczema in predisposed children with or without nutritional intervention was compared with that of non-predisposed children who did not receive intervention. Cox regression was used to adjust for confounding. RESULTS: Predisposed children without nutritional intervention had a 2.1 times higher risk for eczema [95% confidence interval (CI) 1.6-2.7] than children without a familial predisposition. The risk was smaller with nutritional intervention even levelling out to 1.3 (95% CI 0.9-1.9) in children fed eHF-C formula. CONCLUSION: Although direct comparability is somewhat restricted, the data demonstrate that early intervention with hydrolysed infant formulas can substantially compensate up until the age of 6 years for an enhanced risk of childhood eczema due to familial predisposition to allergy.

Intermittent ambiguous stimuli: implicit memory causes periodic perceptual alternations.

When viewing a stimulus that has multiple plausible real-world interpretations, perception alternates between these interpretations every few seconds. Alternations can be halted by intermittently removing the stimulus from view. The same interpretation dominates over many successive presentations, and perception stabilizes. Here we study perception during long sessions of such intermittent presentation. We demonstrate that, rather than causing truly stable perception, intermittent presentation gives rise to a perceptual alternation cycle with its own characteristics and dependencies, different from those during continuous presentation. Alternations during intermittent viewing typically occur once every few minutes--much less frequently than the seconds-scale alternations during continuous viewing. Strikingly, alternations during intermittent viewing occur at fairly regular intervals, making for a surprisingly periodic alternation cycle. The duration of this cycle becomes longer as the blank duration between presentations is increased, reaching dozens of minutes in some cases. We interpret our findings in terms of a mathematical model that describes a neural network with competition between alternative interpretations. Network sensitivities depend on prior dominance, thus providing a memory for past perception. Slow changes in sensitivity produce both perceptual stabilization and the regular but infrequent alternations, meaning that the same memory traces are responsible for both. This model provides a good description of psychophysical findings, and offers several indications regarding their neural basis.

The mechanism of interaction between visual flow and eye velocity signals for heading perception.

A translating eye receives a radial pattern of motion that is centered on the direction of heading. If the eye is rotating and translating, visual and extraretinal signals help to cancel the rotation and to perceive heading correctly. This involves (1) an interaction between visual and eye movement signals and (2) a motion template stage that analyzes the pattern of visual motion. Early interaction leads to motion templates that integrate head-centered motion signals in the visual field. Integration of retinal motion signals leads to late interaction. Here, we show that retinal flow limits precision of heading. This result argues against an early, vector subtraction type of interaction, but is consistent with a late, gain field type of interaction with eye velocity signals and neurophysiological findings in area MST of the monkey.

Impaired visual competition in patients with homonymous visual field defects.

Intense visual training can lead to partial recovery of visual field defects caused by lesions of the primary visual cortex. However, the standard visual detection and discrimination tasks, used to assess this recovery process tend to ignore the complexity of the natural visual environment, where multiple stimuli continuously interact. Visual competition is an essential component for natural search tasks and detecting unexpected events. Our study focused on visual decision-making and to what extent the recovered visual field can compete for attention with the 'intact' visual field. Nine patients with visual field defects who had previously received visual discrimination training, were compared to healthy age-matched controls using a saccade target-selection paradigm, in which participants actively make a saccade towards the brighter of two flashed targets. To further investigate the nature of competition (feed-forward or feedback inhibition), we presented two flashes that reversed their intensity difference during the flash. Both competition between recovered visual field and intact visual field, as well as competition within the intact visual field, were assessed. Healthy controls showed the expected primacy effect; they preferred the initially brighter target. Surprisingly, choice behaviour, even in the patients' supposedly 'intact' visual field, was significantly different from the control group for all but one. In the latter patient, competition was comparable to the controls. All other patients showed a significantly reduced preference to the brighter target, but still showed a small hint of primacy in the reversal conditions. The present results indicate that patients and controls have similar decision-making mechanisms but patients' choices are affected by a strong tendency to guess, even in the intact visual field. This tendency likely reveals slower integration of information, paired with a lower threshold. Current rehabilitation should therefore also include training focused on improving visual decision-making of the defective and the intact visual field.

Attentional control over either of the two competing percepts of ambiguous stimuli revealed by a two-parameter analysis: means do not make the difference.

We studied distributions of perceptual rivalry reversals, as defined by the two fitted parameters of the Gamma distribution. We did so for a variety of bi-stable stimuli and voluntary control exertion tasks. Subjects' distributions differed from one another for a particular stimulus and control task in a systematic way that reflects a constraint on the describing parameters. We found a variety of two-parameter effects, the most important one being that distributions of subjects differ from one another in the same systematic way across different stimuli and control tasks (i.e., a fast switcher remains fast across all conditions in a parameter-specified way). The cardinal component of subject-dependent variation was not the conventionally used mean reversal rate, but a component that was oriented-for all stimuli and tasks-roughly perpendicular to the mean rate. For the Necker cube, we performed additional experiments employing specific variations in control exertion, suggesting that subjects have to a considerable extent independent control over the reversal rate of either of the two competing percepts.

Perceptual compensation for eye torsion.

To correctly perceive visual directions relative to the head, one needs to compensate for the eye's orientation in the head. In this study we focus on compensation for the eye's torsion regarding objects that contain the line of sight and objects that do not pass through the fixation point. Subjects judged the location of flashed probe points relative to their binocular plane of regard, the mid-sagittal or the transverse plane of the head, while fixating straight ahead, right upward, or right downward at 30 cm distance, to evoke eye torsion according to Listing's law. In addition, we investigated the effects of head-tilt and monocular versus binocular viewing. Flashed probe points were correctly localized in the plane of regard irrespective of eccentric viewing, head-tilt, and monocular or binocular vision in nearly all subjects and conditions. Thus, eye torsion that varied by +/-9 degrees across these different conditions was in general compensated for. However, the position of probes relative to the midsagittal or the transverse plane, both true head-fixed planes, was misjudged. We conclude that judgment of the orientation of the plane of regard, a plane that contains the line of sight, is veridical, indicating accurate compensation for actual eye torsion. However, when judgment has to be made of a head-fixed plane that is offset with respect to the line of sight, eye torsion that accompanies that eye orientation appears not to be taken into account correctly.

An invariant for timing of saccades during visual search.

The variable latency of a saccade to the onset of a single target reveals our brain's hypothesis testing about the target's presence. Search in complex scenes involves multiple objects that compete to become fixated. The initiation of a saccade in this case involves two hypotheses: (1) a potential target is present outside the fovea and (2) the currently fixated object is not the target. Previous models suggest that these hypotheses are evaluated independently, each involving a decision signal that races towards threshold. We show here that the skewed latency distributions during search comply with strong competition between these decision signals rather than independence. Moreover, the thresholds for the two competing processes are not independent either but conform to an invariant that suggests that saccades in complex scenes are made when the odds for the target's presence outside the fovea versus within the fovea are about four.

Bcl-2 family members in childhood acute lymphoblastic leukemia: relationships with features at presentation, in vitro and in vivo drug response and long-term clinical outcome.

We have found that, in addition to Bcl-2 and Bax, the expression levels of apoptosis inducers (Bad, Bak) and inhibitors (Bcl-xL, Mcl-1) were highly variable in blasts from 78 children with newly diagnosed acute lymphoblastic leukemia (ALL). The patients were enrolled in the national study ALL-7 of the Dutch Childhood Leukemia Study Group. In contrast to Bcl-2 that inversely correlated with %S-phase cells and WBC, and was lower in T than in B-lineage ALL, the Bcl-2 family members were not found to be associated with features at presentation. These expression levels were also compared with drug resistance in in vitro MTT (methyl-thiazol-tetrazolium) assays for prednisolone, vincristine and asparaginase in 46 children. Protein expression levels of the Bcl-2 family were not found to correlate with in vitroresistance to the individual drugs or the combined drug resistance profile. In addition, neither peripheral blast reduction after 1 week of prednisone monotherapy nor long-term disease-free interval or survival showed a correlation with protein expression. Our results indicate that the anti-proliferative function of Bcl-2 dominates its anti-apoptotic function in ALL, but neither Bcl-2 nor the Bcl-2 family members gained prognostic information in the risk-adapted protocol ALL-7.

Kinematics of eye movement control.

In this paper a kinematic description of the restrictions imposed on the eye movements is presented. The restrictions arise from a pattern of nonlinear interactions between desired changes in viewing direction and current eye position. It is shown that various reported relations between eye torsion and viewing direction can be derived by changing only the relative weights of the interactions terms. This descriptive scheme may help to elucidate the control of eye torsion in the brainstem.

Optic flow and the kinematics of eye movements.

For optimal pursuit of a visual target one should avoid rotation about the line of sight. It is shown that the structure of the optic flow during self-motion imposes certain restrictions on eye and head orientation as a function of the gaze direction, if rotation of the eye about the line of sight is avoided. These restrictions result in different strategies for optimal pursuit. Directing the head towards the aim point of the self-motion in combination with the well known kinematic constraint on eye movement (Listing's law) is one such possibility.

The timing of sequences of saccades in visual search.

According to the LATER model (linear approach to thresholds with ergodic rate), the latency of a single saccade in response to target appearance can be understood as a decision process, which is subject to (i) variations in the rate of (visual) information processing; and (ii) the threshold for the decision. We tested whether the LATER model can also be applied to the sequences of saccades in a multiple fixation search, during which latencies of second and subsequent saccades are typically shorter than that of the initial saccade. We found that the distributions of the reciprocal latencies for later saccades, unlike those of the first saccade, are highly asymmetrical, much like a gamma distribution. This suggests that the normal distribution of the rate r, which the LATER model assumes, is not appropriate to describe the rate distributions of subsequent saccades in a scanning sequence. By contrast, the gamma distribution is also appropriate to describe the distribution of reciprocal latencies for the first saccade. The change of the gamma distribution parameters as a function of the ordinal number of the saccade suggests a lowering of the threshold for second and later saccades, as well as a reduction in the number of target elements analysed.

Motion templates with eye velocity gain fields for transformation of retinal to head centric flow.

Heading perception from the optic flow is more difficult during eye rotations than when the eye is stationary, because the centre of the retinal motion identifies the fixation direction rather than the direction of heading. Eye movement signals helps when motion parallax is absent. This paper distinguishes two different possibilities for interactions between eye movement and visual motion signals to perceive heading with a rotating eye. A pre-motion template transformation changes local retinal velocity into head centric velocity. These velocities then feed head centric motion templates. A post-motion template model combines oculomotor signals with retinal motion templates to arrive at head centric flow templates. The latter scheme involves eye velocity gain fields similar to the eye position gain fields as found in area 7a. We propose that the parietal cortex transforms retinal to head centric direction and retinal to head centric flow on the same principle.

Robustness of perception of heading from optic flow.

Heading discrimination in optic flow stimuli was investigated in 5 humans. Flow patterns consisted of a computer generated motion sequence which showed a mixture of randomly moving and coherently-moving points. The motion of the coherently-moving fiducial points was completely determined by the changing position of the observer's simulated vantage point. Ego-rotation as well as ego-translation was simulated. Noise and fiducial points were confined to the ground plane in most experiments. In one experiment the points formed a cloud with no visible horizon. The results indicate that heading perception is robust against degradation of the flow-field by the presence of noise or by the reduction of the lifetime of the fiducial points. The results suggest that points, which move independently from the reference frame as formed by the fiducial points, are to a large extent removed from the analysis of optic flow by the visual process which derives the heading. The motion of recognizable points at infinity (like the horizon) appears to be essential for robust heading perception in the presence of ego-rotations.

Judgements of heading.

To study the contribution of vision to the perception of ego-motion, one often dissociates the retinal flow from the corresponding extra-retinal information on eye, head and body movement. This puts the observer in a conflict concerning the experienced ego-motion. When the retinal flow of a translating and rotating eye is shown to a stationary eye, observes often perceive ego-motion on a curved path. In contrast, when they receive the same retinal flow with a rotating eye subjects correctly perceive the simulated rectilinear ego-motion. Thus, different visual representations of ego-motion gain precedence when using the conflict stimulus and when using conditions in which the visual and extra-retinal information accord. Because the flow-pattern can be decomposed in many different ways, the brain could represent the same flow-pattern as a rotation about an axis through the eye plus rectilinear ego-motion or a rotation about an axis outside the eye (corresponding to circular ego-motion) plus motion towards the axis of rotation. The circular motion path percept minimizes the conflict with extra-retinal eye movement information if the axis of rotation is placed at the fixation point. However, in simulated eye rotation displays subjects also perceive illusory motion in depth of the stationary fixation point. This illusory motion is argue to reflect the ego-centric decomposition. Errors are small when subjects judge their heading on the basis of this illusory motion. For the same display much larger errors are made, however, when subjects judge heading from the entire motion pattern, which often results in perceived ego-motion on a curved path. This indicates that subjects can choose between tow different representations of ego-motion resulting in different perceived heading.

Predicting the present direction of heading.

Humans perceive heading accurately when they rotate their eyes. This is remarkable, because (1) the pursuit eye movement makes the retinal flow more complicated; and (2) the eye rotation causes a continuous change of the heading direction on the retina. The first problem prevents a simple association of the centre of flow on the retina with the heading direction. To solve it, the brain needs to take into account the flow associated with the eye's rotation. But even if this is done correctly, the resulting estimate of the heading is retino-centric and changing over time. Thus, the processing time to retrieve the heading from the flow field will cause a lag with respect to the actual heading direction. We investigated the latency for heading perception. We presented step wise changes of the centre of expanding flow to stationary and moving eyes. This mimics the movement of the heading direction across the retina, but avoids the complicating effects of rotational flow. For a stationary eye, we found a bias in perceived heading that corresponds to a latency of 300 ms or more. Yet, errors in heading perception are marginal normally, because we found an opposite bias for the moving eye, which counters the errors due to latency and a changing retino-centric heading direction. This suggests that the current heading direction is predicted from the extra-retinal signal and the delayed visual signals.