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•An AO-PS (action observation - proprioceptive stimulation) protocol was proposed.•Oxyhemoglobin (HbO) concentration changes were evaluated with fNIRS.•TMS assessed primary motor cortex (M1) excitability changes before and after AO-PS.•AO-PS increased HbO concentration changes in sensorimotor and associative areas.•Superior parietal lobule activity correlated with long-term changes in M1 activity. The aim of this study was to investigate changes in cortical hemodynamic activity within a frontoparietal network during the administration of an innovative action observation (AO) and proprioceptive stimulation (PS) protocol, and to examine whether this activity could predict the efficacy of the protocol in evoking M1 plasticity, reflected in significant long-term changes in M1 excitability. AO-PS was composed of 50 bursts of combined stimuli. Each burst consisted of five couples of AO and PS during which participants observed a video showing thumb opposition movements and simultaneously received a mechanical vibration on the extensor pollicis brevis muscle (stimulation frequency 80 Hz). During AO-PS, the hemodynamic activity was measured by means of functional Near-Infrared Spectroscopy. Recruitment curves were assessed using transcranial magnetic stimulation before, immediately, 30 and 60 min after AO-PS, to evaluate changes in M1 excitability. During AO-PS, a significant increase in oxyhemoglobin (HbO) concentration changes was found in the following Brodmann Areas (BA): left and right BA6, BA44, and BA43, left BA3, BA4, BA40 and BA7. The highest increment was found in the left BA4. In left BA7 and BA40 the time-to-peak in HbO concentration changes were reached significantly later than in the other BAs. On average, no significant changes were observed after AO-PS administration in M1 excitability, but HbO concentration changes in the left BA7 correlated with plasticity index. These findings highlight the involvement of sensorimotor and associative fronto-parietal regions during AO-PS. Additionally, the activity of the left BA7 revealed the plasticity induced by AO-PS in M1.

•Nine-Hole peg test was compared with a new task involving the sensorimotor domain.•Sensorimotor and prefrontal activity during manual dexterity was assessed by fNIRS.•Right BA10 and BA11 are the substrate for cognitive planning in manual dexterity.•BA10 activity correlates with increased time to perform the nine-hole peg test.•Cognitive domain should be considered when manual dexterity is investigated. Manual dexterity is referred to as the skill to perform fine motor movements and it has been assumed to be associated to the cognitive domain, as well as the sensorimotor one. In this work, we investigated with functional near-infrared spectroscopy the cortical activations elicited by the execution of the 9-HPT, i.e., a standard test evaluating manual dexterity in which nine pegs were taken, placed into and then removed from nine holes on a board as quickly as possible. For comparison, we proposed a new active control task mainly involving the sensorimotor domain, in which the pegs must be placed and removed using the same single hole (1-HPT). Behaviorally, we found two distinct groups based on the difference between the execution time of the 9-HPT and the 1-HPT (ΔHPT). Cortical areas belonging to the network controlling reaching and grasping movements were active in both groups; however, participants showing a large ΔHPT presented significantly higher activation in prefrontal cortical areas (right BA10 and BA11) during 9-HPT and 1-HPT performance with respect to the participants with a small ΔHPT, who showed a deactivation in BA10. Unexpectedly, we observed a significant linear relationship between ΔHPT and right BA10 activity. This suggested that participants performing the 9-HPT more slowly than the 1-HPT recruited prefrontal areas implicitly exploiting the cognitive skills of planning, perhaps in search of a motor strategy to solve the test activating attentional and cognitive control processes, but this resulted not efficient and instead increased the time to accomplish a manual dexterity task.

Background Treadmill-based gait training is part of rehabilitation programs focused on walking abilities. The use of handrails embedded in treadmill systems is debated, and current literature only explores the issue from a behavioral perspective. Methods We examined the cortical correlates of treadmill walking in healthy participants using functional near-infrared spectroscopy. We investigated whether the utilization of treadmill handrails at varying walking speeds could affect cortical activation associated with the task, and we evaluated potential differences in task-based functional connectivity across the various walking conditions. Results Significant differences in cortical activation were found between the two walking speeds (3 and 5 km/h) in the unsupported condition; these differences were reduced when using the handrails. Specifically, cortical activation was significantly higher when the participants swung their arms freely while walking at a speed of 5 compared to 3 km/h in several Brodmann’s Areas (BA): left BA10, BA3 and BA39, and right BA10, BA9, BA8, BA3, and BA40. No significant differences were found when participants were holding onto the handrails. A significant difference was found in the left BA40 between the two speeds, regardless of whether the participants were holding onto the handrails. Furthermore, at the higher speed and without the use of handrails, a wider pattern of task-based functional connectivity was observed, with significantly stronger connectivity between the left BA10 and BA40. Conclusions We suggest that speed and handrails use play a role in walking cortical activity patterns, therefore they are key ingredients to take into account when planning a rehabilitation program.

Time-of-day is rarely considered during experimental protocols investigating motor behavior and neural activity. The goal of this work was to investigate differences in functional cortical connectivity at rest linked to the time of the day using functional Near-Infrared Spectroscopy (fNIRS). Since resting-state brain is shown to be a succession of cognitive, emotional, perceptual, and motor processes that can be both conscious and nonconscious, we studied self-generated thought with the goal to help in understanding brain dynamics. We used the New-York Cognition Questionnaire (NYC-Q) for retrospective introspection to explore a possible relationship between the ongoing experience and the brain at resting-state to gather information about the overall ongoing experience of subjects. We found differences in resting-state functional connectivity in the inter-hemispheric parietal cortices, which was significantly greater in the morning than in the afternoon, whilst the intra-hemispheric fronto-parietal functional connectivity was significantly greater in the afternoon than in the morning. When we administered the NYC-Q we found that the score of the question 27 (“during RS acquisition my thoughts were like a television program or film”) was significantly greater in the afternoon with respect to the morning. High scores in question 27 point to a form of thought based on imagery. It is conceivable to think that the unique relationship found between NYC-Q question 27 and the fronto-parietal functional connectivity might be related to a mental imagery process during resting-state in the afternoon.

In the seed-based method for studying functional connectivity (FC), seed selection is relevant. Here, we propose a new methodological approach for resting-state FC analysis of hand motor networks using the individual hand motor hotspot (hMHS) as seed. Nineteen right-handed healthy volunteers underwent a transcranial magnetic stimulation (TMS) session and resting-state fMRI. For each subject, the hMHS in both hemispheres was identified by TMS with contralateral abductor pollicis brevis muscle as target, as the site eliciting the highest and most reliable motor evoked potentials. Seed regions were built on the coordinates on the cortex corresponding to the individual left and right hMHS. For comparison, the left and right Brodmann’s area 4 (BA4) masks extracted from a standard atlas were used as seed. The left and right hMHS showed FC patterns at rest mainly including sensorimotor regions, with a bilateral connectivity only for the left hMHS. The statistical contrast BA4>hMHS, for both hemispheres, showed different extension and lateralization of the functionally connected cortical regions. On the contrary, no voxels survived the opposite contrast (hMHS>BA4). This suggests that the detection of individual hand motor seeds by TMS allows to identify functionally connected motor networks that are more specific with respect to those obtained starting from the a priori atlas-based identification of the primary motor cortex.

When humans move both hands simultaneously, bimanual coupling or interference can occur. The circles‐lines paradigm is used to study the bimanual coupling and interference effects: Participants simultaneously draw either lines or circles with both hands (congruent), or draw lines with one hand and circles with the other hand (incongruent condition). Despite extensive behavioral research on bimanual coupling with this paradigm, our knowledge of the neural circuitry involved remains limited. Here, we capitalized on the advantages provided by functional near‐infrared spectroscopy to unveil the neural substrates of bimanual coupling within an ecologically valid experimental setting. Behavioral results confirmed previous literature, showing that the shapes become more oval due to the interference between the hands, causing the circle to resemble a line and vice versa. Additionally, performance in the congruent condition correlated with performance in the incongruent condition. From a neural perspective, we observed greater activity in sensorimotor areas and the right premotor area during the incongruent compared to the congruent condition. A novel temporal analysis of the time course of oxyhemoglobin signals revealed that the right hemisphere reached maximum amplitude before the left during the incongruent condition and revealed differences between conditions in parietal areas, showing that bimanual interference is associated not only with motor areas but also with associative areas. Finally, right inferior parietal lobe activity correlated with bimanual performance, suggesting a role for this area in bimanual tasks when the motor program of one hand is influenced by sensorimotor information from the contralateral hand. Our study demonstrates fNIRS effectiveness in investigating bimanual interference during the circles‐lines paradigm. fNIRS allows correct drawing positions, ensuring ecological validity. Performance in congruent tasks predicts incongruent performance. Time‐course analysis shows parietal differences, with the right hemisphere peaking earlier during the incongruent condition. Right inferior parietal lobe activity correlates with bimanual interference.

Purpose This study aims to investigate inter-image intra-observer variability of macular, and optic disc (ONH) microvasculature measurements of glaucomatous and normal subjects using Swept-Source Optical Coherence Tomography Angiography (OCT-A) (OCT Topcon ImageNet 6; DRI OCT Triton, Topcon Corporation, JAPAN) - based imaging data analysis and processing with a newly made quantitative approach. Methods A total of 20 glaucomatous and 20 healthy eyes underwent three OCT-A scanning of the ONH and macula. Macular and papillary and peripapillary vascular networks were calculated. For each eye, eighteen scans were analyzed using a novel approach: custom MATLAB 2021b scripts were employed for imaging analyses. Grayscale distribution was performed using the histcounts MATLAB function with 51 bins. For all layers, the vascular layer coefficient of variation (vl CoV) of the three measures were performed. The vl CoV difference between the two groups was analyzed by Student t-test. Results In glaucomatous eyes, the vl CoV ranged from 4.49% to 8.54%, while in the control group from 3.58% to 8.32%. Both groups exhibited higher CoVs when assessing the optic disc. The papillary and macular microvasculature reproducibility was comparable between groups. Conclusions Utilizing Swept-Source OCT-A images our study has identified an easy and reproducible method that appears to be fast and can assist physicians in assessing macular and ONH perfusion with less inter-image variability, particularly in the 70 μm superficial area of the optic disc. The high reliability obtained suggested that this method could be useful as early clinical biomarker.