Francesco Di Russo | Università degli Studi di Roma Foro Italico (original) (raw)

Papers by Francesco Di Russo

Space perception was investigated in right brain damaged patients with (N=13) and without neglect... more Space perception was investigated in right brain damaged patients with (N=13) and without neglect (N=5; control group). Patients were requested to localise a target tachistoscopically flashed at various eccentricities along the horizontal meridian. All patients had an intact visual field and spared ability to manually point to a target. To segregate magno- and parvo-pathway activity, stimuli modulated in either luminance or chromatic contrast were used. Patients were required to verbally report the stimulus position (verbal task) or to manually point to the stimulus (pointing task). Neglect patients reported the stimuli in the left visual field closer to the centre than they actually were. In the verbal test, underestimation was about 7 deg at the most eccentric position tested (20 deg), and decreased linearly for smaller eccentricities. The effect was similar but less marked in the pointing task. No difference was found for stimuli with luminance or chromatic contrast. Space undere...

bioRxiv (Cold Spring Harbor Laboratory), Dec 21, 2021

BACKGROUND It is unclear whether the Bereitschaftspotential (BP) recorded in humans during action... more BACKGROUND It is unclear whether the Bereitschaftspotential (BP) recorded in humans during action preparation mirrors motor areas activation escalation, or if its early and late phases reflect the engagement of different functional networks. OBJECTIVE Here, we aimed at recording the TMS evoked-potentials (TEP) stimulating the supplementary motor area (SMA) to assess whether and how cortical excitability and functional connectivity of this region change as the BP increases. We hypothesize that, at later stages, the SMA functional network should become more connected to regions relevant for the implementation of the final motor plan. METHODS We performed TMS-EEG recordings on fourteen healthy subjects during the performance of a visuomotor Go/No-go task, eliciting and recording cortical activity and functional connectivity at-700 ms and-300 ms before the onset of visual stimuli over the SMA. RESULTS When approaching stimulus onset, and thus BP peak, the SMA increased its functional connectivity with movement-related structures in the gamma and alpha bands, indicating a regional top-down preparation to implement the motor act. Beta-band connectivity, instead, was maintained constant for the whole BP time-course, being potentially related to sustained attention required by the experimental task. CONCLUSION These findings reveal that the BP is not a mere result of increased activation of the SMA, but the functional networks in which this region is involved qualitatively changes over time, becoming more related to the execution of the motor act. .

Psychology of Sport and Exercise, Mar 1, 2023

Cognitive Neuroscience, Sep 8, 2020

Available literature shows sex-related differences in both anatomy and functions of the auditory ... more Available literature shows sex-related differences in both anatomy and functions of the auditory cortex. However, only few data are available on passive listening. By means of event-related potentials (ERPs), we analyzed the proactive and reactive stages of processing related to passive listening in 36 healthy young participants, equally balanced between genders. The anterior positivity (aP), a newly discovered pre-stimulus component originating in auditory cortices and indexing auditory readiness, was not different between genders; the post-stimulus components (the N1 and the N2, originating in primary and secondary auditory cortices) were larger in females than males. These results not only provide significant insights on sex-related differences during listening, but also encourage the potential use of passive tasks, which allow for better understanding of basic neural processing, without interferences from cognitive requirements of active tasks.

NeuroImage, Mar 1, 2006

Human cortical plasticity has been studied after peripheral sensory alterations due to amputation... more Human cortical plasticity has been studied after peripheral sensory alterations due to amputations or grafts, while sudden Fquasi-physiological_ changes in the dimension of body parts have not been investigated yet. We examined the cortical reorganization in achondroplastic dwarfs submitted to progressive elongation (PE) of lower limbs through the Ilizarov technique. This paradigm is ideal for studying cortical plasticity because it avoids the perturbation connected with deafferentation and reafferentation. Somatosensory evoked-potentials (SEP) and fMRI studies were performed before and after PE during foot and knee stimulation, above and below the surgical fracture. A body schema test was also performed. Following PE, cortical modifications were observed in the primary somatosensory cortex for foot stimulation and in higher order somatosensory cortices for foot and knee. The former modifications tended to decrease 6 months after the elongation ending, whereas the latter tended to persist. Results are interpreted in terms of cortical adaptation mediated by temporary disorganization.

Cognitive Neurodynamics, Nov 30, 2022

The aim of this study was to describe the spectral features of pre-stimulus event-related potenti... more The aim of this study was to describe the spectral features of pre-stimulus event-related potential (ERP) components elicited in visual tasks such as the Bereitschaftspotential (BP), prefrontal negativity (pN) and visual negativity (vN). ERPs are considered time-locked and phase-locked (evoked) activity, but we have also analyzed the non-phase but time-locked (induced) activity in the same interval by applying the temporal spectral evolution (TSE) method. Participants (N = 26) were tested in a passive task, a simple response task (SRT) and a discriminative response task (DRT), where EEG activity was recorded with 64 scalp electrodes. We analyzed the time-frequency modulations (phase and non-phase) prior to the onset of the stimuli in the sub-delta, delta, theta, alpha, beta, and gamma frequency bands. The results showed that all the pre-stimulus ERP components were mainly regulated by evoked activity in the sub-delta band. On the other hand, induced activity seems to be linked to evoked responses but with a different psychophysiological role. We concluded that other preparatory cognitive mechanisms associated with ERPs can also be detected by the TSE method. This finding may suggest underlying mechanisms in non-phase activity and requires the addition of non-phase activity analysis to the traditional analysis (phase and evoked activity).

International Journal of Psychophysiology

Gait & Posture, 2018

S33 one subject, evidenced that the different IMUs are substantially equivalent in term of stabil... more S33 one subject, evidenced that the different IMUs are substantially equivalent in term of stability. Even when a difference in stability was significant, its value was very small. A possible interpretation of those small differences may consists in a stabilizing effect of a larger IMU mass and size. Nonetheless this larger dimensions may have a negative effect in terms of encumbrance onto the body and possibly interfering with the task performances. Therefore the operative choice about IMU and IMU location should result as a trade-off among different quality features.

Biological Psychology, 2018

Background. Motor and inhibitory control rely on frontal cortex activity, which is known to reach... more Background. Motor and inhibitory control rely on frontal cortex activity, which is known to reach full maturation only in late adolescence. The development of inhibitory control has been studied using event-related potentials (ERP), focusing on reactive processing (i.e. the N2 and the P3 components). Scarce information exists concerning pre-stimulus activity as that represented by the Bereinshafstpotential (BP) and by the prefrontal negativity (pN). Further, no literature exists concerning the post-stimulus components originating within the anterior insula (pN1, pP1, pP2). This study aims at associating children performance with these motor-cognitive processing in frontal brain areas. Methods. High-resolution EEG recordings were employed to measure ERPs from 18 children (12 years old) and 18 adults (28 years old) during a visuo-motor discriminative response task. Response time (RT), commission (CE) and omission errors, and RT variability were compared between groups. At brain level, two pre-stimulus (BP and pN) and seven post-stimulus (P1; pN1; N1; pP1; N2; pP2; P3) ERP components were compared between groups. Results. Children showed slower and more variable RTs and poorer inhibition (higher CEs) than adults. At electrophysiological level, children presented smaller BP and pN. After stimulus onset, children showed lower amplitude of N1, pP1, P3, and pP2 components. The P1, pP1, N2 and P3 were delayed compared to adults. Conclusions. Our results demonstrate that children are characterized by less intense task-related proactive activities in frontal cortex, which may account for subsequent poor and delayed reactive processing and, thus, for inaccurate and slow performance.

Clinical Neurophysiology, 2020

Introduction: Neuronavigation systems (NS) are a valuable tool in clinical and experimental neuro... more Introduction: Neuronavigation systems (NS) are a valuable tool in clinical and experimental neuroscience procedures such as in transcranial magnetic stimulation (TMS), providing accurate positioning of the coil throughout a session (Julkunen et al., 2009). Yet, the quality of the stimulus depends on the operator's skills, which are responsible for positioning the coil on the target and holding it still during the stimulation. Losing accuracy over time is inevitable for a human operator. Robots have been used to decrease the variability and improve the reproducibility of TMS coil positioning. However, robotized-TMS is not widely used due to the low portability, high cost, and closed-source development platforms. Objectives: To solve these issues, this work aimed to develop an open-source platform for collaborative robots (cobots) for navigated TMS. Creating an integrated development environment for new technologies on robotized-TMS and allowing users to build their features on demand. Materials & Methods: Our group have been developing the opensource InVesalius Navigator for navigated TMS, written in Python language, and compatible with multiple tracking devices. InVesalius Navigator coil positioning guidance was selected as a suitable platform to develop the cobot control. The cobot iiwa (KUKA Robotics) was used. Communication between the software and the cobot was made through TCP/IP protocol. A Java language server application was implemented for iiwa, and a Python client was created in InVesalius Navigator, allowing the NS to send the coil target positioning to iiwa. The validation of the developed protocol was performed by quantifying the precision and accuracy of the NS. Accuracy error was defined as the Euclidean distance between the coordinates measured in the image space during navigation and the actual coordinate in the simulated phantom image. Results: The cobot provided the position and orientation of a tool or instrument attached to its flange, enabling interconnection between the robot, the neuroimaging, and the patient's real-world anatomy. The communication strategy allowed the neuronavigation system to receive in real-time the coordinates of the instrument attached to the robot. Besides, the developed platform allowed to mark neuronal structures in the NS and send as instructions for the robot positioning. The mean accuracy error was estimated at 1.05 mm. The variability was calculated as the standard deviation of mean accuracy error and equal to 0.49 mm. Conclusion: An open-source, high-end platform of cobot-TMS is being created and might contribute to improving the reproducibility and accuracy of non-invasive brain stimulation techniques. Partial financial support: FAPESP2013/07669-0, CNPq. Reference Julkunen P et al. Comparison of navigated and non-navigated transcranial magnetic stimulation for motor cortex mapping, motor threshold and motor evoked potentials. Neuroimage [Internet] 2009];44(3):790-5.

International Journal of Psychophysiology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

NeuroImage, 2019

Clinical Neurophysiology, 2016

This study investigated the cerebral sources of the visual eventrelated potential (ERP) with the ... more This study investigated the cerebral sources of the visual eventrelated potential (ERP) with the help of simultaneous recording of functional magnetic resonance imaging (fMRI). As tasks, in addition to a standard two-stimuli visual ''oddball" paradigm, we applied a similar paradigm, in which the rare (target) stimuli were omitted in a sequence of regularly presented visual stimuli. Pre-stimulus ERP showed larger prefrontal activity over the righ hemisphere in the omitted-target task. Post-stimulus ERP showed a clear P1/N1/ P2/Pp2/P3 complex during the standard ''oddball" paradigm, whereas during the ''omitted target" task, only the Pp2 and P3 components were present. The P3 was reduced amplitude and increased latency (from 450 to 520 ms). fMRI showed, during both tasks, activations in lateral frontal, fronto-operculum, anterior insula regions, prevailing on the right. Minor activations were observed bilaterally in the parietal cortex near the intraparietal sulcus and in posterior temporal regions, also more evident on the right hemisphere. The ''omitted task" paradigm showed larger fMRI activations in prefrontal areas. These results showed for the first time the strong top-down preparatory cognitive control in the ''omitted target" task and highlight the endogenous nature of P3.

International Journal of Psychophysiology, 2021

NeuroImage, Aug 1, 2017

Proactive brain control optimizes upcoming actions and inhibits unwanted responses. In the presen... more Proactive brain control optimizes upcoming actions and inhibits unwanted responses. In the present eventrelated potential (ERP) study, participants freely decided in advance whether to respond or not to an upcoming stimulus, then prepared or not the action according to their decision; finally, a stimulus was delivered, and subjects had to respond (or not). During the decision-making stage, a prefrontal negativity raised bilaterally in case no-response was decided, reflecting the first brain signal of proactive inhibition. Simultaneously, slow activity raised over premotor cortices independently from the decision taken, and then raised during the preparation phase only in the case of response decision (as a sort of accelerator). When the decision was not to respond, the prefrontal activity remained sustained (as a sort of brake) and showed a right-lateralized distribution during the preparation phase. Overall, we described the time-course of a proactive acceleratingbraking system regulating self-control of actions.

Brain Structure & Function, Dec 3, 2019

In the present study, we investigated neural correlates associated with gender differences in a s... more In the present study, we investigated neural correlates associated with gender differences in a simple response task (SRT) and in a discriminative response task (DRT) by means of event-related potential (ERP) technique. 120 adults participated in the study, and, based on their sex, were divided into two groups matched for age and education level. Behavioral performance was assessed with computing response speed, accuracy rates and response consistency. Pre-and post-stimulus ERPs were analyzed and compared between groups. Results indicated that males were faster than females in all tasks, while females were more accurate and consistent than males in the more complex tasks. This different behavioral performance was associated with distinctive ERP features. In the preparation phase, males showed smaller prefrontal negativity (pN) and visual negativity (vN), interpreted as reduced cognitive preparation to stimulus occurrence and reduced reliance on sensory proactive readiness, respectively. In the post-stimulus phase, gender differences were present over occipital (P1, N1, P2 components) and prefrontal (pN1, pP1, pP2 components) areas, suggesting allocation of attentional resources at distinct stages of information processing in the two groups. Overall, the present data provide evidence in favor of a more proactive and cautious cognitive processing in females and a more reactive and fast cognitive processing in males. In addition, we confirm that (1) gender is an important variable to be considered in ERP studies on perceptual processing and decision making, and (2) the pre-stimulus component analysis can provide useful information concerning neural correlates of upcoming performance.

Frontiers in Human Neuroscience, 2013

We studied the effects of transcutaneous electrical nerve stimulation (TENS) in six rightbrain-da... more We studied the effects of transcutaneous electrical nerve stimulation (TENS) in six rightbrain-damaged patients with left unilateral spatial neglect (USN), using both standard clinical tests (reading, line, and letter cancelation, and line bisection), and electrophysiological measures (steady-state visual-evoked potentials, SSVEP). TENS was applied on left neck muscles for 15 , and measures were recorded before, immediately after, and 60 after stimulation. Behavioral results showed that the stimulation temporarily improved the deficit in all patients. In cancelation tasks, omissions and performance asymmetries between the two hand-sides were reduced, as well as the rightward deviation in line bisection. Before TENS, SSVEP average latency to stimuli displayed in the left visual half-field [LVF (160 ms)] was remarkably longer than to stimuli shown in the right visual half-field [RVF (120 ms)]. Immediately after TENS, latency to LVF stimuli was 130 ms; 1 h after stimulation the effect of TENS faded, with latency returning to baseline. TENS similarly affected also the latency SSVEP of 12 healthy participants, and their line bisection performance, with effects smaller in size. The present study, first, replicates evidence concerning the positive behavioral effects of TENS on the manifestations of left USN in right-brain-damaged patients; second, it shows putatively related electrophysiological effects on the SSVEP latency. These behavioral and novel electrophysiological results are discussed in terms of specific directional effects of left somatosensory stimulation on egocentric coordinates, which in USN patients are displaced toward the side of the cerebral lesion. Showing that visual-evoked potentials latency is modulated by proprioceptive stimulation, we provide electrophysiological evidence to the effect that TENS may improve some manifestations of USN, with implications for its rehabilitation.