PolyMorph: A P300 Polymorphic Speller

P300 is an electric signal emitted by brain about 300 milliseconds after a rare, but relevant-for-the-user event. Even if it is hard to identify and it provides a low-rate communication channel, it can be used in cases in which other evoked potentials fail. One of the applications of this signal is a speller that enables subjects who lost the control of their motor pathways to communicate by selecting one by one each character of a sentence in a matrix containing all the alphabet symbols. This paper provides an improvement of this paradigm and it aims at reducing both the error rate and the time required to spell a sentence by exploiting the redundancy which is present in all the natural languages

Review of the therapeutic neurofeedback method using electroencephalography: EEG Neurofeedback

Electroencephalographic neurofeedback (EEG-NFB) represents a broadly used method that involves a real-time EEG signal measurement, immediate data processing with the extraction of the parameter(s) of interest, and feedback to the individual in a real-time. Using such a feedback loop, the individual may gain better control over the neurophysiological parameters, by inducing changes in brain functioning and, consequently, behavior. It is used as a complementary treatment for a variety of neuropsychological disorders and improvement of cognitive capabilities, creativity or relaxation in healthy subjects. In this review, various types of EEG-NFB training are described, including training of slow cortical potentials (SCPs) and frequency and coherence training, with their main results and potential limitations. Furthermore, some general concerns about EEG-NFB methodology are presented, which still need to be addressed by the NFB community. Due to the heterogeneity of research designs in EEG-NFB protocols, clear conclusions on the effectiveness of this method are difficult to draw. Despite that, there seems to be a well-defined path for the EEG-NFB research in the future, opening up possibilities for improvement

Altered Modulation of Silent Period in Tongue Motor Cortex of Persistent Developmental Stuttering in Relation to Stuttering Severity

Motor balance in developmental stuttering (DS) was investigated with Transcranial Magnetic Stimulation (TMS), with the aim to define novel neural markers of persistent DS in adulthood. Eleven DS adult males were evaluated with TMS on tongue primary motor cortex, compared to 15 matched fluent speakers, in a "state" condition (i.e. stutterers vs. fluent speakers, no overt stuttering). Motor and silent period thresholds (SPT), recruitment curves, and silent period durations were acquired by recording tongue motor evoked potentials. Tongue silent period duration was increased in DS, especially in the left hemisphere (P<0.05; Hedge's g or Cohen's dunbiased = 1.054, i.e. large effect size), suggesting a "state" condition of higher intracortical inhibition in left motor cortex networks. Differences in motor thresholds (different excitatory/inhibitory ratios in DS) were evident, as well as significant differences in SPT. In fluent speakers, the left hemisphere may be marginally more excitable than the right one in motor thresholds at lower muscular activation, while active motor thresholds and SPT were higher in the left hemisphere of DS with respect to the right one, resulting also in a positive correlation with stuttering severity. Pre-TMS electromyography data gave overlapping evidence. Findings suggest the existence of a complex intracortical balance in DS tongue primary motor cortex, with a particular interplay between excitatory and inhibitory mechanisms, also in neural substrates related to silent periods. Findings are discussed with respect to functional and structural impairments in stuttering, and are also proposed as novel neural markers of a stuttering "state" in persistent DS, helping to define more focused treatments (e.g. neuro-modulation)

Effect of Transcranial Magnetic Stimulation (TMS) on Parietal and Premotor Cortex during Planning of Reaching Movements

The activation of the superior parietal lobule (SPL) and premotor cortex (PM) has been investigated using transcranial magnetic stimulation (TMS) during planning of reaching movements under visual guidance. A facilitory effect was found when TMS was delivered on the parietal cortex at about half of the time from sight of the target to hand movement, independently of target location in space. Furthermore, at the same stimulation time, a similar facilitory effect was found in PM, which is probably related to movement preparation. This data contributes to the understanding of cortical dynamics in the parieto-frontal network, and suggests that it is possible to interfere with the planning of reaching movements at different cortical points within a particular time window. Since similar effects may be produced at similar times on both the SPL and PM, parallel processing of visuomotor information is likely to take place in these regions

Stuttering as a matter of delay in neural activation: A combined TMS/EEG study

Objective: Brain dynamics in developmental stuttering (DS) are not well understood. The supplementary motor area (SMA) plays a crucial role, since it communicates with regions related to planning/execution of movements, and with sub-cortical regions involved in paced/voluntary acts (such as speech). We used TMS combined with EEG to shed light on connections in DS, stimulating the SMA. Methods: TMS/EEG was recorded in adult DS and fluent speakers (FS), stimulating the SMA during rest. TMS-evoked potentials and source distribution were evaluated. Results: Compared to FS, stutterers showed lower activity of neural sources in early time windows: 66\u2013 82 ms in SMA, and 91\u2013102 ms in the left inferior frontal cortex and left inferior parietal lobule. Stutterers, however, showed higher activations in later time windows (i.e. from 260\u2013460 ms), in temporal/premotor regions of the right hemisphere. Conclusions: These findings represent the functional counterpart to known white matter and cortico- basal-thalamo-cortical abnormalities in DS. They also explain how white matter abnormalities and cortico-basal-thalamo-cortical dysfunctions may be associated in DS. Finally, a mechanism is proposed in which compensatory activity of the non-dominant (right) hemisphere is recruited. Significance: DS may be a disorder of neural timing that appears to be delayed compared to FS; new mechanisms that support stuttering symptoms are inferred; the SMA may be a promising target for neuro-rehabilitation

Visuomotor adaptation changes tactile discrimination: an ERP study

We recorded brain activity in SI, elicited by the electrical stimulation of the right forearm during a 2PTD task (the two point distance selected according to the individual threshold) after visuomotor adaptation sessions, including normal and extended reaches. A reliable increase in brain activity was observed after the visuomotor adaptation with extended but not normal reaches. Visuomotor adaptation changes body representation and preset the tactile circuits involved in the 2TPD task via top-down links from multisensory areas in the posterior parietal cortex into the somatosensory corte

BCI-Based Neuro-Rehabilitation Treatment for Parkinson’s Disease: cases Report

Parkinson's Disease (PD) is characterized by motor and cognitive decay, coupled to an alteration of brain oscillatory patterns. In this study a novel neuro-rehabilitation tool, based on the application of motor imagery into a Brain Computer Interface system, is presented with some preliminary data. Three patients were evaluated (with motor, neuropsychological and EEG testing) before and after a neuro-rehabilitation protocol made by 15 experimental sessions. Patients showed a decrease of freezing of gait severity, an improvement in alpha and beta EEG bands power, and a better performance on some attention and executive tasks

Neurofeedback induced restoration on sensorimotor rhythm after 24h of hand immobilization.

In this study, we examined the effect of neurofeedback on EEG changes due to immobilization of the dominant hand. Desynchronization of the sensorimotor rhythms during motor imagery was used as a tool to investigate brain activity. The study is based on 8 healthy subjects who underwent immobilization of the dominant hand for 24 hours. The electrical activity of the sensorimotor region of the cerebral cortex was registered during mental imagery of hand movements before the immobilization, soon after its removal and after a single session of neurofeedback. The control of the feedback stimuli was based on changes in sensorimotor rhythms produced by imagination of movement. Preliminary results show that immobilization caused changes in alpha and beta rhythms that were rapidly reversed after a single session of neurofeedback. At the end of the full study, if the here presented observations will still hold, the neurofeedback protocol will be proposed for routine rehabilitation sessions in patients suffering partial or total limb disability

Transcranial magnetic stimulation in developmental stuttering: Relations with previous neurophysiological research and future perspectives

Developmental stuttering (DS) is a disruption of the rhythm of speech, and affected people may be unable to execute fluent voluntary speech. There are still questions about the exact causes of DS. Evidence sug- gests there are differences in the structure and functioning of motor systems used for preparing, execut- ing, and controlling motor acts, especially when they are speech related. Much research has been obtained using neuroimaging methods, ranging from functional magnetic resonance to diffusion tensor imaging and electroencephalography/magnetoencephalography. Studies using transcranial magnetic stimulation (TMS) in DS have been uncommon until recently. This is surprising considering the relation- ship between the functionality of the motor system and DS, and the wide use of TMS in motor-related disturbances such as Parkinson\u2019s Disease, Tourette\u2019s Syndrome, and dystonia. Consequently, TMS could shed further light on motor aspects of DS. The present work aims to investigate the use of TMS for under- standing DS neural mechanisms by reviewing TMS papers in the DS field. Until now, TMS has contributed to the understanding of the excitatory/inhibitory ratio of DS motor functioning, also helping to better understand and critically review evidence about stuttering mechanisms obtained from different tech- niques, which allowed the investigation of cortico-basal-thalamo-cortical and white matter/connection dysfunctions