Sensorimotor cortex

Neurofeedback-Linked Suppression of Cortical β Bursts Speeds Up Movement Initiation in Healthy Motor Control: A Double-Blind Sham-Controlled Study

Abnormally increased β bursts in cortical-basal ganglia-thalamic circuits are associated with rigidity and bradykinesia in patients with Parkinson's disease. Increased β bursts detected in the motor cortex have also been associated with longer reaction times (RTs) in healthy participants. Here we further hypothesize that suppressing β bursts through neurofeedback training can improve motor performance in healthy subjects. We conducted a double-blind sham-controlled study on 20 human volunteers (10 females) using a sequential neurofeedback-behavior task with the neurofeedback reflecting the occurrence of β bursts over sensorimotor cortex quantified in real time. The results show that neurofeedback training helps healthy participants learn to volitionally suppress β bursts in the sensorimotor cortex, with training being accompanied by reduced RT in subsequent cued movements. These changes were only significant in the real feedback group but not in the sham group, confirming the effect of neurofeedback training over simple motor imagery. In addition, RTs correlated with the rate and accumulated duration of β bursts in the contralateral motor cortex before the go-cue, but not with averaged β power. The reduced RTs induced by neurofeedback training positively correlated with reduced β bursts across all tested hemispheres. These results strengthen the link between the occurrence of β bursts in the sensorimotor cortex before the go-cue and slowed movement initiation in healthy motor control. The results also highlight the potential benefit of neurofeedback training in facilitating voluntary suppression of β bursts to speed up movement initiation.SIGNIFICANCE STATEMENT This double-blind sham-controlled study suggested that neurofeedback training can facilitate volitional suppression of β bursts in sensorimotor cortex in healthy motor control better than sham feedback. The training was accompanied by reduced reaction time (RT) in subsequent cued movements, and the reduced RT positively correlated with the level of reduction in cortical β bursts before the go-cue, but not with average β power. These results provide further evidence of a causal link between sensorimotor β bursts and movement initiation and suggest that neurofeedback training could potentially be used to train participants to speed up movement initiation.

Neurofeedback Control in Parkinsonian Patients Using Electrocorticography Signals Accessed Wirelessly With a Chronic, Fully Implanted Device

Parkinson's disease (PD) is characterized by motor symptoms such as rigidity and bradykinesia that prevent normal movement. Beta band oscillations (13-30 Hz) in neural local field potentials (LFPs) have been associated with these motor symptoms. Here, three PD patients implanted with a therapeutic deep brain neural stimulator that can also record and wirelessly stream neural data played a neurofeedback game where they modulated their beta band power from sensorimotor cortical areas. Patients' beta band power was streamed in real-time to update the position of a cursor that they tried to drive into a cued target. After playing the game for 1-2 hours each, all three patients exhibited above chance-level performance regardless of subcortical stimulation levels. This study, for the first time, demonstrates using an invasive neural recording system for at-home neurofeedback training. Future work will investigate chronic neurofeedback training as a potentially therapeutic tool for patients with neurological disorders.

Innovative technologies applied to sensorimotor rehabilitation after stroke

Innovative technologies for sensorimotor rehabilitation after stroke have dramatically increased these past 20 years. Based on a review of the literature on "Medline" and "Web of Science" between 1990 and 2013, we offer an overview of available tools and their current level of validation. Neuromuscular electric stimulation and/or functional electric stimulation are widely used and highly suspected of being effective in upper or lower limb stroke rehabilitation. Robotic rehabilitation has yielded various results in the literature. It seems to have some effect on functional capacities when used for the upper limb. Its effectiveness in gait training is more controversial. Virtual reality is widely used in the rehabilitation of cognitive and motor impairments, as well as posture, with admitted benefits. Non-invasive brain stimulation (rTMS and TDCS) are promising in this indication but clinical evidence of their effectiveness is still lacking. In the same manner, these past five years, neurofeedback techniques based on brain signal recordings have emerged with a special focus on their therapeutic relevance in rehabilitation. Technological devices applied to rehabilitation are revolutionizing our clinical practices. Most of them are based on advances in neurosciences allowing us to better understand the phenomenon of brain plasticity, which underlies the effectiveness of rehabilitation. The acceptation and "real use" of those devices is still an issue since most of them are not easily available in current practice.

Neurofeedback for Cerebral Palsy

A double-blind investigation of the relationship between seizure activity and the sleep EEG following EEG biofeedback training

The sleep EEGs of eight medically refractory epileptic patients were examined as part of a double-blind, ABA crossover study designed to determine the effectiveness of EEG biofeedback for the control of seizures. The patients were initially reinforced for one of three EEG criteria recorded from electrodes placed over sensorimotor cortex: (a) suppression of 3- to 7-Hz activity, (b) enhancement of 12- to 15-Hz activity, or (c) simultaneous suppression of 3- to 7-Hz and enhancement of 11- to 19-Hz activity. Reinforcement contingencies were reversed during the second or B phase, and then reinstated in their original form during the final A′ phase. All-night polysomnographic recordings were obtained at the end of each conditioning phase and were subjected to both visual and computer-based power spectral analyses. Four of the patients showed changes in their nocturnal paroxysmal activity that were either partially or totally consistent with the ABA′ contingencies of the study. The spectral data proved difficult to interpret, though two trends emerged from the analyses. Decreases in nocturnal 4- to 7-Hz activity were correlated with decreases in seizure activity, and increases in 8- to 11-Hz activity were correlated with decreases in seizure activity. These findings were shown to strengthen the hypothesis that EEG biofeedback may produce changes in the sleep EEG that are related to seizure incidence.

Biofeedback Training of the Sensorimotor Electroencephalogram Rhythm in Man: Effects on Epilepsy

Summary Previous work in cats demonstrated a discrete 12–16 Hz rhythm in sensorimotor cortex (SMR), present only during absence of movement, that could be operantly conditioned. Trained cats were resistant to drug-induced seizures. Similar biofeedback training procedures were employed with epileptic and nonepileptic human subjects, utilizing lights, tones, and slides. Initially SMR activity was detected only at low voltage by tuned filters. Biofeedback training sessions resulted in a significant increase in this activity after 2 to 3 months. Learned SMR responses in nonepileptic subjects were trains of pure or polyrhythmic 12–16 Hz activity at 20 to 25 μV over central and frontal areas. Although epileptic subjects failed to develop the enhanced SMR amplitude, they did demonstrate increased occurrence of this frequency. Training in four epileptic patients, who previously were not controlled by chemotherapy, was accompanied by a significant reduction of EEG and clinical epileptic manifestations, as indicated by sequential power spectral analysis, clinical EEG records, and seizure logs. Tonic-clonic and myoclonic seizures were most markedly reduced. RÉsumé Des travaux antérieurs chez des chats ont démontré qu'il y a un rythme discret à 12–16 Hz dans le cortex sensorimoteur (SMR) évident seulement au repos mais suceptible d'étre conditioné. Les chats entrainés étaient résistants aux crises provoquées par des drogues. Des procédés analogues de biofeedback training ont été employeś chez des personnes avec ou sans épilepsie, en utilisant des lumières des sons et des diapositives. Au début, le rythme du cortex sensorimoteur était détecté seulement à des bas voltages avec des filtres à sonorisation appropriée. A la suite de séances de biofeedback training, il y avait après 2–3 mois, une augmentation significative de L'activité rythmique des régions sensorimotrices. Chez les sujets sans épilepsies, les activités acquises à la suite de L'apprentissage étaient constituées par des bouffées d'activités mono- ou polyrythmique à 12–16 Hz et de 20–25 μV d'amplitude, intéressant les régions centrales et frontales. Bien que les sujets avec épilepsie ne soient pas arriveés à augmenter L'amplitude des rythmes des régions sensorimotrices, ils ont cependant mis en évidence une augmentation quantitative de ces rythmes. Chez 4 sujets avec épilepsie qui avant L'entra înement n'étaient pas contrôlés par les médicaments, on a observéà la suite de L'entraînement une diminution significative des decharges paroxystiques sur L'EEG et des crises diminution objectiveée par L'analyse séquentielle des spectres de puissances et par le compte rendu du nombre des crises. Les crises tonico-cloniques et myocloniques etaient le plus remarquablement diminuées. RESUMEN Estudios previos en gatos nan demostrado que un discreto ritmo de 12 a 16 Hz en la corteza sensorial-motora (SMR), registrable solamente en ausencia de movimiento, podía ser condicionado. Los gatos entrenados eran resistentes a los ataques inducidos. Un entrenamiento semejante (bio-feedback) se utilizeó en enfermos epilépticos y en individuos sanos mediante el empleo de luces, tonos y diapositivas. Inicialmente la actividad SMR se registró solamente con voltajes bajos y filtros apropiados. El entrenamiento con retro-información boilógica (biofeedback) produjo un aumento significativo de esta actividad a los 2 o 3 meses. En individuos sanos, las respuestas SMR aprendidas, se expresaban en forma de trenes de una actividad, pura o polirítmica, de 12 a 16 Hz y de 20 a 25 micro-voltios en las areas frontal y central. Los enfermos epilépticos mostraron un aumento de estas frecuencias a pesar de que no se pudo conseguir un incremento de la amplitud SMR. En cuatro enfermos epilépticos entrenados sin posible control farmacológico previo, se consiguió una reducción significativa de las manifestaciones clínicas o electroencefalográficas de la epilepsyía, como demostró el análisis espectral secuencial y los trazados clónicos de EEG Los ataques tónico-clónicos y las mioclónias fueron los que más se redujeron. ZUSAMMEnfassung Frühere Untersuchungen bei Katzen liessen einen diskreten 12 bis 16 Hz-Rhythmus im sensomotorischen Cortex (SMR) erkennen. Er war nur bei Bewegungsruhe vorhanden und konnte konditioniert werden. Trainierte Katzen waren gegenüber medicamentös erzeugten Anfällen resistent. Ahnliche Programme mit biologischem Rückkopplungstraining wurden mit epileptischen und nicht epileptischen Patienten durchgeführt, wobei Licht, Töne und Dias verwendet wurden. Anfangs wurde die SMR.-Aktivität nur mit niedriger Amplitude durch abgestimmte Filter gefunden. Nach 2 bis 3 Monaten dauerndem Training der biologischen Rückkopplung wurde eine signifikante Zunahme dieser Aktivität gefunden. Bei nicht epileptischen Patienten bestanden die erlernten SMR-Ant-worten in Zügen reiner oder polyrhythmischer 12 bis 16 Hz-Aktivität mit 20 bis 25 μV über den zentralen und frontalen Ableitepunkten. Obwohl epileptische Patienten keine verstärkte SMR-Amplitude aufwiesen, zeigten sie doch eine vermehrte Häufigkeit dieser Frequenz. Das Training von 4 epileptischen Patienten, deren Anfälle durch Chemotherapie vorher nicht zu kontrollieren waren, wurde von einer signifikanten Verminderung der epileptischen Manifestationen im EEG und klinisch begleitet. Das zeigten die sequentielle Power-Spektrumanalyse, klinische EEG-Untersuchugnen und Anfallsaufzeichnungen. Tonisch-klonische und myoklonische Anfälle wurden am deutlichsten vermindert.