Verso la comprensione dello stato vegetativo e di minima coscienza.

The limited evidence and inconsistency of purposeful behaviors in patients in a minimally conscious state (MCS) asks for objective electrophysiological marker of the level of consciousness. Here, a comparison between event-related potentials (ERPs) was investigated using different level of stimulus complexity. ERPs were recorded in seventeen patients, 6 of which in vegetative state (VS), 11 in MCS, and 10 controls. Three oddball paradigms with different level of complexity were applied: sine tones, the subject’s own name versus sine tones and other first names. Latencies and amplitudes of N1 and P3 waves were compared. Cortical responses were found in all MCS patients, and in 6 of 11 patients in VS. Healthy controls and MCS patients showed a progressive increase of P3 latency in relation to the level of stimulus complexity. No modulation of P3 latency was observed in the vegetative patients. These results suggest that the modulation of P3 latency related to stimulus complexity may represent an objective index of higher-order processing integration that predicts the recovery of consciousness from VS to MCS when clinical manifestations are inconsistent. A second step was encouraged by the work of Schiff et al. (2007) reporting a MCS patient who responded to deep brain stimulation (DBS). We explored six patients that participated in an ABA design alternating between repetitive transcranial magnetic stimulation (rTMS) and peripheral nerve stimulation. After peripheral stimulation, patients did not exhibit clinical, behavioral, or electroencephalographic (EEG) changes. The frequency of specific and meaningful behaviors increased after rTMS in a patient, along with the absolute and relative power of the EEG δ, β, and α bands. Afterwards, a more consistent sample has been enrolled to reproduce the first encouraging results. Thirty MCS/VS patients participated to a randomized controlled trial consisting of transcranial stimulations with transcranial direct current stimulation (tDCS) and rTMS. Patients in MCS showed an increase of long range fronto-parietal connectivity indicating a complex information processing and a decrease of fluctuation of arousal . VS patients did not. These results suggest that rTMS may improve long range connections between remote cortical areas and promote, at some level, recovery of awareness and arousal in MCS patients

Magnetoencephalography in Stroke Recovery and Rehabilitation

Magnetoencephalography (MEG) is a non-invasive neurophysiological technique used to study the cerebral cortex. Currently, MEG is mainly used clinically to localize epileptic foci and eloquent brain areas in order to avoid damage during neurosurgery. MEG might, however, also be of help in monitoring stroke recovery and rehabilitation. This review focuses on experimental use of MEG in neurorehabilitation. MEG has been employed to detect early modifications in neuroplasticity and connectivity, but there is insufficient evidence as to whether these methods are sensitive enough to be used as a clinical diagnostic test. MEG has also been exploited to derive the relationship between brain activity and movement kinematics for a motor-based brain-computer interface. In the current body of experimental research, MEG appears to be a powerful tool in neurorehabilitation, but it is necessary to produce new data to confirm its clinical utility

Assessment of Event-Related EEG Power After Single-Pulse TMS in Unresponsive Wakefulness Syndrome and Minimally Conscious State Patients

In patients without a behavioral response, non-invasive techniques and new methods of data analysis can complement existing diagnostic tools by providing a method for detecting covert signs of residual cognitive function and awareness. The aim of this study was to investigate the brain oscillatory activities synchronized by single-pulse transcranial magnetic stimulation (TMS) delivered over the primary motor area in the time\u2013frequency domain in patients with the unresponsive wakefulness syndrome or in a minimally conscious state as compared to healthy controls. A time\u2013frequency analysis based on the wavelet transform was used to characterize rapid modifications of oscillatory EEG rhythms induced by TMS in patients as compared to healthy controls. The pattern of EEG changes in the patients differed from that of healthy controls. In the controls there was an early synchronization of slow waves immediately followed by a desynchronization of alpha and beta frequency bands over the frontal and centro-parietal electrodes, whereas an opposite early synchronization, particularly over motor areas for alpha and beta and over the frontal and parietal electrodes for beta power, was seen in the patients. In addition, no relevant modification in slow rhythms (delta and theta) after TMS was noted in patients. The clinical impact of these findings could be relevant in neurorehabilitation settings for increasing the awareness of these patients and defining new treatment procedures

P300-Based Brain–Computer Interface Communication: Evaluation and Follow-up in Amyotrophic Lateral Sclerosis

To describe results of training and 1-year follow-up of brain-communication in a larger group of early and middle stage amyotrophic lateral sclerosis (ALS) patients using a P300-based brain–computer interface (BCI), and to investigate the relationship between clinical status, age and BCI performance. A group of 21 ALS patients were tested with a BCI-system using two-dimensional cursor movements. A four choice visual paradigm was employed to training and test the brain-communication abilities. The task consisted of reaching with the cursor one out of four icons representing four basic needs. Five patients performed a follow-up test 1 year later. The clinical severity in all patients were assessed with a battery of clinical tests. A comparable control group of nine healthy subjects was employed to investigate performance differences. Nineteen patients and nine healthy subjects were able to achieve good and excellent cursor movements' control, acquiring at least communication abilities above chance level; during follow-up the patients maintained their BCI-skill. We found mild cognitive impairments in the ALS group which may be attributed to motor deficiencies, while no relevant correlation has been found between clinical data and BCI performance. A positive correlation between age and the BCI-skill in patients was found. Time since training acquisition and clinical status did not affect the patients brain-communication skill at early and middle stage of the disease. A brain-communication tool can be used in most ALS patients at early and middle stage of the disease before entering the locked-in stage

ERRATUM: Effects of combined endurance and resistance training in Amyotrophic Lateral Sclerosis: A pilot, randomized, controlled study

Not available

Preservation of Auditory P300-Like Potentials in Cortical Deafness

The phenomenon of blindsight has been largely studied and refers to residual abilities of blind patients without an acknowledged visual awareness. Similarly, “deaf hearing” might represent a further example of dissociation between detection and perception of sounds

Verso la comprensione dello stato vegetativo e di minima coscienza.

The limited evidence and inconsistency of purposeful behaviors in patients in a minimally conscious state (MCS) asks for objective electrophysiological marker of the level of consciousness. Here, a comparison between event-related potentials (ERPs) was investigated using different level of stimulus complexity. ERPs were recorded in seventeen patients, 6 of which in vegetative state (VS), 11 in MCS, and 10 controls. Three oddball paradigms with different level of complexity were applied: sine tones, the subject’s own name versus sine tones and other first names. Latencies and amplitudes of N1 and P3 waves were compared. Cortical responses were found in all MCS patients, and in 6 of 11 patients in VS. Healthy controls and MCS patients showed a progressive increase of P3 latency in relation to the level of stimulus complexity. No modulation of P3 latency was observed in the vegetative patients. These results suggest that the modulation of P3 latency related to stimulus complexity may represent an objective index of higher-order processing integration that predicts the recovery of consciousness from VS to MCS when clinical manifestations are inconsistent. A second step was encouraged by the work of Schiff et al. (2007) reporting a MCS patient who responded to deep brain stimulation (DBS). We explored six patients that participated in an ABA design alternating between repetitive transcranial magnetic stimulation (rTMS) and peripheral nerve stimulation. After peripheral stimulation, patients did not exhibit clinical, behavioral, or electroencephalographic (EEG) changes. The frequency of specific and meaningful behaviors increased after rTMS in a patient, along with the absolute and relative power of the EEG δ, β, and α bands. Afterwards, a more consistent sample has been enrolled to reproduce the first encouraging results. Thirty MCS/VS patients participated to a randomized controlled trial consisting of transcranial stimulations with transcranial direct current stimulation (tDCS) and rTMS. Patients in MCS showed an increase of long range fronto-parietal connectivity indicating a complex information processing and a decrease of fluctuation of arousal . VS patients did not. These results suggest that rTMS may improve long range connections between remote cortical areas and promote, at some level, recovery of awareness and arousal in MCS patients.Le limitate evidenze e la fluttuazione dei comportamenti intenzionali neiin pazienti in stato di minima coscienza (SMC) richiedono la ricerca di un indice marcatore elettrofisiologico obiettivo del livello di coscienza. Nel presente studio, è stato mostrato un confronto tra potenziali evento-correlati (ERP) utilizzando diversi livelli di complessità di stimolo. Gli ERP sono stati registrati in diciassette pazienti, di cui sei in stato vegetativo (SV), 11 in SMC, e 10 controlli sani. I partecipanti sono stati sottoposti a tre paradigmi di diverso grado di complessità: toni puri, il nome proprio del soggetto verso toni puri, e verso altri nomi. Sono state riscontrate risposte corticali in tutti i pazienti in SMC, ed in 6 degli 11 pazienti in SV. I controlli sani ed i pazienti in SMC hanno mostrato un progressivo aumento della latenza dell’onda P300 in relazione al livello di complessità dello stimolo. Nessuna modulazione di latenza è stata osservata nei pazienti in SV. Questi risultati suggeriscono che la modulazione di latenza della P300 relativa a complessità dello stimolo può rappresentare un indice obiettivo dell’integrazione tra aree di elaborazione di ordine superiore, presupposto necessario per il recupero della coscienza. Un secondo passo è stato incoraggiato dal lavoro di Schiff e coll. (2007) che riportarono il miglioramento clinico di un paziente in SMC dopo stimolazione cerebrale profonda (DBS). Abbiamo studiato sei pazienti sottoponendoli ad uno studio di tipo ABA con alternanza tra stimolazione magnetica transcranica ripetitiva (rTMS) e stimolazione dei nervi periferici. Dopo stimolazione periferica, i pazienti non ha evidenziato variazioni dei quadric clinico, comportamentale o elettroencefalografico (EEG). Tuttavia, dopo la rTMS, un paziente manifestò un aumento della frequenza di specifici comportamenti coscienti, associato ad un incremento della potenza assoluta e relativa delle bande EEG alfa, beta e delta. Successivamente, è stato arruolato un campione più consistente di pazienti per riprodurre i primi incoraggianti risultati. Trenta pazienti in SV/SMC hanno partecipato ad uno studio controllato randomizzato che comportava l’utilizzo di stimoli transcranici con stimolazione transcranica a corrente continua (tDCS) e rTMS. I pazienti in SMC hanno mostrato un aumento di connettività fronto-parietale, che indica una complessa elaborazione delle informazioni sensoriali, ed una diminuzione della fluttuazione dell’arousal. Il quadro dei pazienti in SV rimase invariato. Questi risultati suggeriscono che la rTMS può migliorare le connessioni a lungo raggio tra remote aree corticali e promuovere, in qualche modo, il recupero di coscienza nei pazienti in SMC

An EEG-based BCI platform to improve arm reaching ability of chronic stroke patients by means of an operant learning training with a contingent force feedback

The Brain Computer Interface platform described in this paper was implemented to enhance neuroplasticity of a stroke-damaged brain in order to promote recovery of motor functions like reaching, fundamentally important in a healthy daily life. To this scope a closed-loop between the stroke patients\u2019 brain and a robotic arm is established by means of a real-time identification of the cerebral activity related to the movement and its transformation in a force feedback delivered by the robot. In particular, an operant-learning strategy is employed: while patients are performing the motor task they receive a feedback of their neural activity. If the latter agrees with the expected neurophysiological hypothesis, they are helped by the robotic arm in completing the task. The method trains patients to control the modulation of sensorimotor rhythms of their perilesional area and, at the same time, it should induce them to associate that modulation to the reaching movement. In this way, the modification of the neural activity becomes an alternative tool for controlling the impaired reaching ability bypassing the damaged brain area. Preliminary encouraging results were found in both the two first patients recruited in the program