Sensorimotor integration processing in Diabetic Retinopathy and Diabetic Peripheral Neuropathy

This study evaluated the direct link between visual perception and related motor output responses during an optic flow stimulation which induced a perception of forward movement, and during a driving task using a simulator. The experiments focussed on the evaluation of two different complications of diabetes, diabetic retinopathy and diabetic peripheral neuropathy (DPN), in order to evaluate the different contributions of both central and peripheral nervous factors in affecting the sensorimotor integration process in diabetes. Study I. The aim was to assess how optic flow processing contributes to the control of posture and whether it requires the predominant activation of cortical networks involved in motion perception or the intervention of subcortical loops. People with retinopathy and people who had undergone laser treatment showed a higher postural instability compared to control subjects. Differing retinal functionality produced different postural strategies. Based on these findings, postural control seems to be a process dependent on perceptual analysis via feed-forward cortical circuits. Study II. The aim was to assess whether diabetes was associated with alterations of visual gaze behaviour and/or neuromuscular impairment that might adversely affect driving performance. The potential for impaired driving performance with diabetes seems to be represented by diminished eye-steering coordination. While proprioception function seems to indicate the potential for improvement, a slower production of strength in the plantar flexor muscles seems not to influence accelerator pedal control during a driving simulation task in people with diabetes (with and without diabetic peripheral neuropathy). These results confirm the role of visual perception and eye movements in guiding human movements during dailylife activities. In particular, we demonstrated the detrimental effects of diabetes and the different contribution of diabetic retinopathy and diabetic peripheral neuropathy in affecting both central and peripheral components of the sensorimotor integration process

The effects of dehydration on metabolic and neuromuscular functionality during cycling

This study aimed to determine the effects of dehydration on metabolic and neuromuscular functionality performance during a cycling exercise. Ten male subjects (age 23.4 \ub1 2.7 years; body weight 74.6 \ub1 10.4 kg; height 177.3 \ub1 4.6 cm) cycled at 65% VO2max for 60 min followed by a time-to-trial (TT) at 95% VO2max, in two different conditions: dehydration (DEH) and hydration (HYD). The bioelectrical impedance vector analysis (BIVA) and body weight measurements were performed to assess body fluid changes. Heart rate (HR), energy cost, minute ventilation, oxygen uptake, and metabolic power were evaluated during the experiments. In addition, neuromuscular activity of the vastus medialis and biceps femoris muscles were assessed by surface electromyography. After exercise induced dehydration, the bioimpedance vector significantly lengthens along the major axis of the BIVA graph, in conformity with the body weight change ( 122%), that indicates a fluid loss. Metabolic and neuromuscular parameters significantly increased during TT at 95% VO2max with respect to constant workload at 65% of VO2max. Dehydration during a one-hour cycling test and subsequent TT caused a significant increase in HR, while neuromuscular function showed a lower muscle activation in dehydration conditions on both constant workload and on TT. Furthermore, a significant difference between HYD and DEH for TT duration was found

Dematerialized participation challenges: Methods and practices for online focus groups

This study explores the limitations and benefits of different approaches to conducting online focus groups and illustrates an online focus group protocol used within the Value for Schools project in Italy. According to the project evaluation design, 13 online focus groups were organized, with the participation of 101 teachers and 37 school principals. The protocol setup, incorporation, and reorganization of the indications have been discussed in the literature, addressing the methodological and practical issues, such as the selection of participants and preliminary communication with them; the web conference platform (Zoom Business); timing, as well as access times and mode; the roles of the researchers involved (moderator, co-host technical assistant, co-host-observer, co-host-animator) and their integration spaces; technological support; and animation tools. The recording and transcription tools and subsequent analysis of the textual corpus are presented. Finally, the authors discuss the validation and reliability of online focus group protocols

Influence of heading perception in the control of posture

The optic flow visual input directly influences the postural control. The aim of the present study was to examine the relationship between visually induced heading perception and postural stability, using optic flow stimulation. The dots were accelerated to simulate a heading direction to the left or to the right of the vertical midline. The participants were instructed to indicate the perceived optic flow direction by making a saccade to the simulated heading direction. We simultaneously acquired electromyographyc and center of pressure (COP) signals. We analysed the postural sway during three different epochs: (i) the first 500\u202fms after the stimulus onset, (ii) 500\u202fms before saccade onset, epoch in which the perception is achieved and, (iii) 500\u202fms after saccade onset. Participants exhibited a greater postural instability before the saccade, when the perception of heading was achieved, and the sway increased further after the saccade. These results indicate that the conscious representation of the self-motion affects the neural control of posture more than the mere visual motion, producing more instability when visual signals are contrasting with eye movements. It could be that part of these effects are due to the interactions between gaze shift and optic flow

Effect of heading perception on microsaccade dynamics

The present study shows the relationship between microsaccades and heading perception. Recent research demonstrates that microsaccades during fixation are necessary to overcome loss of vision due to continuous stimulation of the retinal receptors, even at the potential cost of a decrease in visual acuity. The goal of oculomotor fixational mechanisms might be not retinal stabilization, but controlled image motion adjusted to be optimal for visual processing. Thus, patterns of microsaccades may be exploited to help to understand the oculomotor system, aspects of visual perception, and the dynamics of visual attention. We presented an expansion optic flow in which the dot speed simulated a heading directed to the left or to the right of the subject, who had to signal the perceived heading by making a saccade toward the perceived direction. We recorded microsaccades during the optic flow stimulation to investigate their characteristics before and after the response. The time spent on heading perception was similar between right and left direction, and response latency was shorter during correct than incorrect responses. Furthermore, we observed that correct heading perception is associated with longer, larger and faster microsaccade characteristics. The time-course of microsaccade rate shows a modulation across the perception process similar to that seen for other local perception tasks, while the main direction is oriented toward the opposite side with respect to the perceived heading. Microsaccades enhance visual perception and, therefore, represent a fundamental motor process, with a specific effect for the build-up of global visual perception of space

Angle of gaze and optic flow direction modulate body sway

none5noOptic flow is a crucial signal in maintaining postural stability. We sought to investigate whether the activity of postural muscles and body sway was modulated by eye position during the view of radial optic flow stimuli. We manipulated the spatial distribution of dot speed and the fixation point position to simulate specific heading directions combined with different gaze positions. The experiments were performed using stabilometry and surface electromyography (EMG) on 24 right-handed young, healthy volunteers. Center of pressure (COP) signals were analyzed considering antero-posterior and medio-lateral oscillation, COP speed, COP area, and the prevalent direction of oscillation of body sway. We found a significant main effect of body side in all COP parameters, with the right body side showing greater oscillations. The different combinations of optic flow and eye position evoked a non-uniform direction of oscillations in females. The EMG analysis showed a significant main effect for muscle and body side. The results showed that the eye position modulated body sway without changing the activity of principal leg postural muscles, suggesting that the extraretinal input regarding the eye position is a crucial signal that needs to be integrated with perceptual optic flow processing in order to control body sway.mixedRaffi, Milena; Piras, Alessandro; Persiani, Michela; Perazzolo, Monica; Squatrito, SalvatoreRaffi, Milena; Piras, Alessandro; Persiani, Michela; Perazzolo, Monica; Squatrito, Salvator