Explore the vast range of titles available.

Embodied and grounded cognition theories state that cognitive processing is built upon sensorimotor systems. In the context of numerical cognition, support to this framework comes from the interactions between numerical processing and the hand actions of reaching and grasping documented in skilled adults. Accordingly, mechanisms for the processing of object size and location during reach and grasp actions might scaffold the development of mental representations of numerical magnitude. The present study exploited motor adaptation to test the hypothesis of a functional overlap between neurocognitive mechanisms of hand action and numerical processing. Participants performed repetitive grasping of an object, repetitive pointing, repetitive tapping, or passive viewing. Subsequently, they performed a symbolic number comparison task. Importantly, hand action and number comparison were functionally and temporally dissociated, thereby minimizing context-based effects. Results showed that executing the action of pointing slowed down the responses in number comparison. Moreover, the typical distance effect (faster responses for numbers far from the reference as compared to close ones) was not observed for small numbers after pointing, while it was enhanced by grasping. These findings confirm the functional link between hand action and numerical processing, and suggest new hypotheses on the role of pointing as a meaningful gesture in the development and embodiment of numerical skills.

Motion artifacts are a significant source of noise in many functional near-infrared spectroscopy (fNIRS) experiments. Despite this, there is no well-established method for their removal. Instead, functional trials of fNIRS data containing a motion artifact are often rejected completely. However, in most experimental circumstances the number of trials is limited, and multiple motion artifacts are common, particularly in challenging populations. Many methods have been proposed recently to correct for motion artifacts, including principle component analysis, spline interpolation, Kalman filtering, wavelet filtering and correlation-based signal improvement. The performance of different techniques has been often compared in simulations, but only rarely has it been assessed on real functional data. Here, we compare the performance of these motion correction techniques on real functional data acquired during a cognitive task, which required the participant to speak aloud, leading to a low-frequency, low-amplitude motion artifact that is correlated with the hemodynamic response. To compare the efficacy of these methods, objective metrics related to the physiology of the hemodynamic response have been derived. Our results show that it is always better to correct for motion artifacts than reject trials, and that wavelet filtering is the most effective approach to correcting this type of artifact, reducing the area under the curve where the artifact is present in 93% of the cases. Our results therefore support previous studies that have shown wavelet filtering to be the most promising and powerful technique for the correction of motion artifacts in fNIRS data. The analyses performed here can serve as a guide for others to objectively test the impact of different motion correction algorithms and therefore select the most appropriate for the analysis of their own fNIRS experiment. •A comparison of motion artifact correction techniques on real data is performed.•Motion artifact correction is a crucial step in the fNIRS signal processing stream.•Wavelet filtering is a powerful tool for motion artifact correction.

•No increase in sample size for studies comparing groups over the last 20 years.•Most studies use block design and grand average of oxy-Hb as outcome.•Lack of deoxy-Hb analysis in block-based designs.•Most studies lack conditions to evaluate how the Stroop effect is solved.•Comparisons between studies are difficult due to heterogeneity of test setup. Functional near-infrared spectroscopy (fNIRS) has emerged as a valuable technique for studying cognitive neuroscience, with the Stroop test being a predominant paradigm. We conducted a scoping review of 133 fNIRS–Stroop studies published over the past 20 years to map methodological trends. Most studies used a block design and lacked sufficient control conditions to analyze the Stroop effect. Although the sample sizes increased in recent years, the majority had an inadequate number of participants, especially for studies comparing two or more samples. Nearly all reported only oxygenated hemoglobin (oxy-Hb), while deoxygenated hemoglobin (deoxy-Hb) analyses appeared mainly in event-related designs. We observed substantial heterogeneity in Stroop variants and control tasks, hindering cross-study comparisons. Although the Stroop test is well suited to fNIRS, few studies adopted designs or theoretical frameworks capable of isolating specific cognitive processes or underlying neural circuits; instead, many focused on group differences or intervention effects. This review underscores the necessity for greater methodological standardization in future research to improve the interpretation of the Stroop test within the domain of cognitive neuroscience.

Several studies have evaluated the effect of anodal transcranial direct current stimulation (tDCS) over the prefrontal cortex (PFC) for the enhancement of working memory (WM) performance in healthy older adults. However, the mixed results obtained so far suggest the need for concurrent brain imaging, in order to more directly examine tDCS effects. The present study adopted a continuous multimodal approach utilizing functional near-infrared spectroscopy (fNIRS) to examine the interactive effects of tDCS combined with manipulations of reward motivation. Twenty-one older adults (mean age = 69.7 years; SD = 5.05) performed an experimental visuo-spatial WM task before, during and after the delivery of 1.5 mA anodal tDCS/sham over the left prefrontal cortex (PFC). During stimulation, participants received performance-contingent reward for every fast and correct response during the WM task. In both sessions, hemodynamic activity of the bilateral frontal, motor and parietal areas was recorded across the entire duration of the WM task. Cognitive functions and reward sensitivity were also assessed with standard measures. Results demonstrated a significant impact of tDCS on both WM performance and hemodynamic activity. Specifically, faster responses in the WM task were observed both during and after anodal tDCS, while no differences were found under sham control conditions. However, these effects emerged only when taking into account individual visuo-spatial WM capacity. Additionally, during and after the anodal tDCS, increased hemodynamic activity relative to sham was observed in the bilateral PFC, while no effects of tDCS were detected in the motor and parietal areas. These results provide the first evidence of tDCS-dependent functional changes in PFC activity in healthy older adults during the execution of a WM task. Moreover, they highlight the utility of combining reward motivation with prefrontal anodal tDCS, as a potential strategy to improve WM efficiency in low performing healthy older adults. •fNIRS and tDCS were used in healthy older adults performing a working memory task.•Bilateral prefrontal hemodynamic activity increased with left prefrontal anodal tDCS.•Anodal tDCS combined with reward motivation improves working memory in older adults.

•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.

We propose a new probe placement method for multichannel functional Near Infrared Spectroscopy (fNIRS) based on the ICBM152 template, the most commonly used reference brain for neuroimaging. Our method is based on the use of a physical model of the ICBM152 head surface as reference scalp and its validity is supported by previous investigations of cranio-cerebral correlation. The method, intended for fNIRS group studies, dispenses with the use of individual MRI scan and digitizing procedure for each participant. The present approach offers a fast, simple, reproducible and straightforward method to place the probes on the head surface according to the MNI coordinates of the regions of interest with an average measurement error similar to those of previous methods. This ensures that fNIRS results can be readily compared within the neuroimaging community, both across studies and techniques.

Objective: The aims of the study were to test the short-term and long-term efficacy of repetitive γ-tACS over the left DLPFC to improve visuospatial working memory performance in the spatial capacity delayed response task (SCDRT). Methods: In a single blind placebo-controlled study, 35 healthy young adults were randomly assigned to three sessions of either active γ-tACS (n = 18) or passive sham γ-tACS (n = 17) The design allowed us to evaluate the influence of the stimulation protocol (active vs. sham), the stimulation session number (day 1 to 3), the session block (before stimulation, during stimulation and after stimulation) and the VSWM retention load (1, 3, 5 or 7 stimuli) on the response speed and accuracy. Results: Active γ-tACS selectively improved VSWM performance on day 2 and 3, and the effect was greater following stimulation rather than during stimulation. Significant effects were seen concerning response speed but not accuracy. The VSWM performance gains of the active γ-tACS were no longer present in the long-term at a follow-up session after two weeks. Conclusions: The present study provides novel evidence for a selective improvement in VSWM performance with three repeated sessions of γ-tACS in young adults through the entrainment of gamma rhythms in the left DLPFC.

Previous functional near-infrared spectroscopy (fNIRS) studies indicated that the prefrontal cortex (PFC) is involved in the maintenance of the postural balance after external perturbations. So far, no studies have been conducted to investigate the PFC hemodynamic response to virtual reality (VR) tasks that could be adopted in the field of functional neurorehabilitation. The aim of this fNIRS study was to assess PFC oxygenation response during an incremental and a control swing balance task (ISBT and CSBT, respectively) in a semi-immersive VR environment driven by a depth-sensing camera. It was hypothesized that: i) the PFC would be bilaterally activated in response to the increase of the ISBT difficulty, as this cortical region is involved in the allocation of attentional resources to maintain postural control; and ii) the PFC activation would be greater in the right than in the left hemisphere considering its dominance for visual control of body balance. To verify these hypotheses, 16 healthy male subjects were requested to stand barefoot while watching a 3 dimensional virtual representation of themselves projected onto a screen. They were asked to maintain their equilibrium on a virtual blue swing board susceptible to external destabilizing perturbations (i.e., randomizing the forward-backward direction of the impressed pulse force) during a 3-min ISBT (performed at four levels of difficulty) or during a 3-min CSBT (performed constantly at the lowest level of difficulty of the ISBT). The center of mass (COM), at each frame, was calculated and projected on the floor. When the subjects were unable to maintain the COM over the board, this became red (error). After each error, the time required to bring back the COM on the board was calculated (returning time). An eight-channel continuous wave fNIRS system was employed for measuring oxygenation changes (oxygenated-hemoglobin, O2Hb; deoxygenated-hemoglobin, HHb) related to the PFC activation (Brodmann Areas 10, 11 and 46). The results have indicated that the errors increased between the first and the second level of difficulty of the ISBT, then decreased and remained constant; the returning time progressively increased during the first three levels of difficulty and then remained constant. During the CSBT, the errors and the returning time did not change. In the ISBT, the increase of the first three levels of difficulty was accompanied by a progressive increase in PFC O2Hb and a less consistent decrease in HHb. A tendency to plateau was observable for PFC O2Hb and HHb changes in the fourth level of difficulty of the ISBT, which could be partly explained by a learning effect. A right hemispheric lateralization was not found. A lower amplitude of increase in O2Hb and decrease in HHb was found in the PFC in response to the CSBT with respect to the ISBT. This study has demonstrated that the oxygenation increased over the PFC while performing an ISBT in a semi-immersive VR environment. These data reinforce the involvement of the PFC in attention-demanding balance tasks. Considering the adaptability of this virtual balance task to specific neurological disorders, the absence of motion sensing devices, and the motivating/safe semi-immersive VR environment, the ISBT adopted in this study could be considered valuable for diagnostic testing and for assessing the effectiveness of functional neurorehabilitation. •Prefrontal cortex activation to semi-immersive virtual swing balance task by fNIRS•Bilateral prefrontal activation modulated by the swing balance task difficulty•Bilateral prefrontal cortex involved in postural control attention-demanding tasks

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.