Influence of frontal-to-parietal connectivity in pseudoneglect: A cortico-cortical paired associative stimulation study

Pseudoneglect is a set of visuospatial biases that entails a behavioral advantage for stimuli appearing in the left hemifield compared to the right one. Although right hemisphere dominance for visuospatial processing has been invoked to explain this phenomenon, its neurophysiological mechanisms are still debated, and the role of intra- and inter-hemispheric connectivity is yet to be defined. The present study explored the possibility of modulating pseudoneglect in healthy participants through a cortico-cortical paired associative stimulation protocol (ccPAS): a non-invasive brain stimulation protocol that manipulates the interplay between brain regions through the repeated, time-locked coupling of two transcranial magnetic stimulation (TMS) pulses. In the first experiment, healthy participants underwent a frontal-to-parietal (FP) and a parietal-to-frontal (PF) ccPAS. In the FP protocol, the first TMS pulse targeted the right frontal eye field (FEF), and the second pulse the right inferior parietal lobule (IPL), two critical areas for visuospatial and attentional processing. In the PF condition, the order of the pulses was reversed. In both protocols, the inter-stimulus interval (ISI) was 10 ms. Before and after stimulation, pseudoneglect was assessed with a landmark task and a manual line bisection task. A second experiment controlled for ccPAS timing dependency by testing FP-ccPAS with a longer ISI of 100 ms. Results showed that after administering the FP-ccPAS with the ISI of 10 ms, participants' leftward bias in the landmark task increased significantly, with no effects in the manual line bisection task. The other two protocols tested were ineffective. Our findings showed that ccPAS could be used to modulate pseudoneglect by exploiting frontal-to-parietal connectivity, possibly through increased top-down attentional control. FP-ccPAS could represent a promising tool to investigate connectivity properties within visuospatial and attentional networks in the healthy and as a potential rehabilitation protocol in patients suffering from severe visuospatial pathologies

The past, present, and future of the Brain Imaging Data Structure (BIDS)

The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a history of how the standard has developed and grown over time. We outline the principles behind the project, the mechanisms by which it has been extended, and some of the challenges being addressed as it evolves. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS

A tool to induce cross-modal Hebbian-like plasticity within the primary somatosensory cortex

Background In recent years neuroscientific evidence highlighted the cross-modal, mirror-like, properties of the primary somatosensory cortex (S1): this area is activated not only by one’s own somatosensation, but also by the observation of tactile stimulation of another person’s body. We explored whether the activity of S1, and the associated tactile processing, could be enhanced by activating Hebbian plasticity-induction mechanisms through their visual, mirror-based, recruitment. To this aim, we developed a novel, cross-modal, Paired Associative Stimulation protocol (cm-PAS). Methods Cm-PAS consists in the repetitive, time-locked pairing of a visual stimulus depicting a hand being touched and a Transcranial Magnetic Stimulation (TMS) pulse over S1. In four experiments we tested the i) timing ii) cortical area iii) visual stimulation selectivity of the cm-PAS, and iv) the role of predictive coding mechanisms. Cm-PAS effects were assessed by measuring tactile acuity (behavioural index) and Somatosensory Evoked Potentials (SEPs, neurophysiological index in experiment 3). Results Results show an enhancement of tactile acuity only with strict delay between the TMS pulse and the visual touch stimulus; an increase of SEPs following only S1 stimulation paired with a visuo-tactile stimulus. Moreover, we found that preventing the anticipation of the visual touch changes the time-course of cortical-visual interactions

Hebbian associative plasticity in the visuo-tactile domain: A cross-modal paired associative stimulation protocol

We developed and assessed the effects of a novel cross-modal protocol aimed at inducing associative (Hebbian-like) plasticity in the somatosensory cortical system through vision. Associative long-term potentiation can be induced in the primary somatosensory cortex (S1) by means of paired associative stimulation (PAS), in which a peripheral electrical stimulation of the median nerve is repeatedly paired with a transcranial magnetic stimulation (TMS) pulse over S1. Considering the mirror proprieties of S1, the cross-modal PAS (cm-PAS) consists of repetitive observation of bodily tactile stimulations, paired with TMS pulses over the contralateral S1. Through three experiments in healthy participants, we demonstrate that the cm-PAS is able to induce excitatory plastic effects with functional significance in S1, improving somatosensory processing at both behavioral (tactile acuity) and neurophysiological (somatosensory-evoked potentials) levels. The plastic effects induced by cm-PAS depend on the interval (20 m s) between the visual stimulus and the magnetic pulse, the targeted cortical site (S1), and the tactile content of the visual stimulus, which must represent a touch event. Such specificity implies the recruitment of cross-modal, mirror-like, mechanisms in S1, which are able to visually promote associative synaptic plasticity in S1 likely through the recruitment of predictive coding processe

Touch anticipation mediates cross-modal Hebbian plasticity in the primary somatosensory cortex

Paired associative stimulation (PAS) protocols can be used to induce Hebbian plasticity in the human brain. A modified, cross-modal version, of the PAS (cross-modal PAS, cm-PAS) has been recently developed. The cm-PAS consists in the repetitive pairings of a transcranial magnetic stimulation (TMS) pulse over the primary somatosensory cortex (S1) and a visual stimulus depicting a hand being touched; a 20 ms of inter-stimulus interval (ISI) is required to affect S1 plasticity, in turn modulating tactile acuity and somatosensory evoked potentials. The present study explores the role of anticipatory simulation in the cm-PAS efficacy, which could be responsible for such a short ISI. To this aim, we compared the effect of the original, fixed-frequency, cm-PAS to that of a jittered version, in which the time interval between trials was not steady but jittered, hence avoiding the anticipation of the upcoming visual-touch stimulus. Moreover, in the jittered PAS, the ISI between the paired stimulations was varied: it could match the early, somatosensory-driven, activation of S1 (20 ms), or the mirror recruitment of S1 by touch observation (150 ms). Results showed that tactile acuity is enhanced by the fixed-frequency cm-PAS, with an ISI of 20 ms between paired stimulation (visual-touch stimulus and TMS pulse over S1), and also by the jittered cm-PAS but only if the ISI is of 150 ms. These findings suggest that the cm-PAS with a jittered frequency, by preventing an anticipatory pre-activation of S1, delays the timing of the interaction between the visual-touch stimulus and the cortical pulse. On a broader perspective, our study highlights the possible involvement of sensory anticipation, likely through mirror-like simulation mechanisms, in tactile mirroring, as well as its influence of the optimal interval between the afferent and the magnetic pulse during PAS protocols

The Past, Present, and Future of the Brain Imaging Data Structure (BIDS)

International audienceThe Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a history of how the standard has developed and grown over time. We outline the principles behind the project, the mechanisms by which it has been extended, and some of the challenges being addressed as it evolves. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS

The Past, Present, and Future of the Brain Imaging Data Structure (BIDS)

The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a history of how the standard has developed and grown over time. We outline the principles behind the project, the mechanisms by which it has been extended, and some of the challenges being addressed as it evolves. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS

The Past, Present, and Future of the Brain Imaging Data Structure (BIDS)

The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a history of how the standard has developed and grown over time. We outline the principles behind the project, the mechanisms by which it has been extended, and some of the challenges being addressed as it evolves. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS

Survey of neonatal respiratory care and surfactant administration in very preterm infants in the Italian neonatal network

Introduction: Variation of respiratory care is described between centers around the world.The Italian Neonatal Network (INN), as a national group of the Vermont-Oxford Network (VON) allows to perform a wide analysis of respiratory care in very low birth weight infants. Methods:We analyzed the dataset of infants enrolled in the INN in 2009 and 2010 and, for surfactant administration only, from 2006 to 2010 from 83 participating centers. All definitions are those of the (VON). A questionnaire analysis was also performed with a questionnaire on centers practices. Results: We report data for 8297 infants. Data on ventilator practices and outcomes are outlined. Variation for both practices and outcome is found. Trend in surfactant administration is also analyzed. Conclusions. The great variation across hospitals in all the surveyed techniques points to the possibility of implementing potentially better practices with the aim of reducing unwanted variation. These data also show the power of large neonatal networks in identifying areas for potential improvement. \ua9 Mattioli 1885