The challenge of controlling an auditory BCI in the case of severe motor disability.

Background: The locked-in syndrome (LIS), due to a lesion in the pons, impedes communication. This situation can also be met after some severe brain injury or in advanced Amyotrophic Lateral Sclerosis (ALS). In the most severe condition, the persons cannot communicate at all because of a complete oculomotor paralysis (Complete LIS or CLIS).

Infraclinical detection of voluntary attention in coma and post-coma patients using electrophysiology.

Objective: Early functional evaluation and prognosis of patients with disorders of consciousness is a major challenge that clinical assessments alone cannot solve. Objective measures of brain activity could help resolve this uncertainty. We used electroencephalogram at bedside to detect voluntary attention with a paradigm previously validated in healthy subjects.

Auditory attention alterations in migraine: A behavioral and MEG/EEG study.

Objectives: To evaluate alterations of top-down and/or bottom-up attention in migraine and their cortical underpinnings.

Methods: 19 migraineurs between attacks and 19 matched control participants performed a task evaluating jointly top-down and bottom-up attention, using visually-cued target sounds and unexpected task-irrelevant distracting sounds. Behavioral responses and magneto- and electro-encephalography signals were recorded.

The auditory oddball paradigm revised to improve bedside detection of consciousness in behaviorally unresponsive patients.

Active paradigms requiring subjects to engage in a mental task on request have been developed to detect consciousness in behaviorally unresponsive patients. Using auditory ERPs, the active condition consists in orienting patient's attention toward oddball stimuli. In comparison with passive listening, larger P300 in the active condition identifies voluntary processes.

Increased Evoked Potentials to Arousing Auditory Stimuli during Sleep: Implication for the Understanding of Dream Recall.

High dream recallers (HR) show a larger brain reactivity to auditory stimuli during wakefulness and sleep as compared to low dream recallers (LR) and also more intra-sleep wakefulness (ISW), but no other modification of the sleep macrostructure. To further understand the possible causal link between brain responses, ISW and dream recall, we investigated the sleep microstructure of HR and LR, and tested whether the amplitude of auditory evoked potentials (AEPs) was predictive of arousing reactions during sleep. Participants (18 HR, 18 LR) were presented with sounds during a whole night of sleep in the lab and polysomnographic data were recorded.

BCI in patients with disorders of consciousness: clinical perspectives.

The reestablishment of communication is one of the main goals for patients with disorders of consciousness (DOC). It is now established that many DOC patients retain the ability to process stimuli of varying complexity even in the absence of behavioural response. Motor impairment, fatigue, attention disorders might contribute to the difficulty of communication in this population.

MMN and novelty P3 in coma and other altered states of consciousness: a review.

In recent decades, there has been a growing interest in the assessment of patients in altered states of consciousness. There is a need for accurate and early prediction of awakening and recovery from coma. Neurophysiological assessment of coma was once restricted to brainstem auditory and primary cortex somatosensory evoked potentials elicited in the 30 ms range, which have both shown good predictive value for poor coma outcome only.

Alpha reactivity to complex sounds differs during REM sleep and wakefulness.

We aimed at better understanding the brain mechanisms involved in the processing of alerting meaningful sounds during sleep, investigating alpha activity. During EEG acquisition, subjects were presented with a passive auditory oddball paradigm including rare complex sounds called Novels (the own first name - OWN, and an unfamiliar first name - OTHER) while they were watching a silent movie in the evening or sleeping at night. During the experimental night, the subjects' quality of sleep was generally preserved.

Attention orienting dysfunction with preserved automatic auditory change detection in migraine.

Objective: To investigate automatic event-related potentials (ERPs) to an auditory change in migraine patients.

Methods: Auditory ERPs were recorded in 22 female patients suffering from menstrually-related migraine and in 20 age-matched control subjects, in three sessions: in the middle of the menstrual cycle, before and during menses. In each session, 200 trains of tone-bursts each including two duration deviants were presented in a passive listening condition.

Alpha reactivity to first names differs in subjects with high and low dream recall frequency.

Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG).

Brain reactivity differentiates subjects with high and low dream recall frequencies during both sleep and wakefulness.

The neurophysiological correlates of dreaming remain unclear. According to the "arousal-retrieval" model, dream encoding depends on intrasleep wakefulness. Consistent with this model, subjects with high and low dream recall frequency (DRF) report differences in intrasleep awakenings.

What is the specificity of the response to the own first-name when presented as a novel in a passive oddball paradigm? An ERP study.

One's own first-name is a special stimulus: one's attention is more likely captured by hearing one's own first-name than by hearing another first-name. Previous event-related potential (ERP) studies demonstrated that this special stimulus produces differential responses both in active and in passive condition. Such results suggest that passively hearing one's own first-name triggers processing levels generally activated by the explicit detection of stimuli.

Exacerbated attention orienting to auditory stimulation in migraine patients.

Objective: To investigate long-term (LTH) and short-term (STH) habituation of auditory event-related potentials (ERPs) during a migraine cycle, using a classic habituation paradigm.

Methods: In 22 patients suffering from menstrually-related migraine and in 20 age-matched control subjects, auditory ERPs were recorded in 3 sessions: in the middle of the menstrual cycle, before menses, and during menses. In 12 patients, a migraine attack occurred during one of the peri-menses sessions.

Event-related potentials (MMN and novelty P3) in permanent vegetative or minimally conscious states.

Objective: To assess markers of cognition, if any, in patients in a permanent vegetative state (PVS).

Methods: Event-related potential (ERP) mapping was performed on 27 patients in permanent (4-261 months after coma onset) vegetative (PVS, n=16) or minimally conscious states (MCS, n=11) due to anoxia (n=18) or other aetiologies (n=9). Mismatch negativity (MMN) to duration-deviant tones and novelty P3 (nP3) to the subject's own name were recorded according to a paradigm previously validated in healthy volunteers and comatose patients.

Novelty P3 elicited by the subject's own name in comatose patients.

Objective: To assess patterns of novelty P3 elicited by the subject's own name (SON) in comatose patients and to compare SON novelty P3 prognostic value with that of mismatch negativity (MMN).

Methods: A passive oddball paradigm, previously validated in healthy subjects, including duration deviants and SON presented as a novel was applied in 50 severe comatose patients on average 20 days after coma onset. The outcome was assessed 3 months after coma onset.

Odd sound processing in the sleeping brain.

How does the sleeping brain process external stimuli, and in particular, up to which extent does the sleeping brain detect and process modifications in its sensory environment? In order to address this issue, we investigated brain reactivity to simple auditory stimulations during sleep in young healthy subjects. Electroencephalogram signal was acquired continuously during a whole night of sleep while a classical oddball paradigm with duration deviance was applied. In all sleep stages, except Sleep Stage 4, a mismatch negativity (MMN) was unquestionably found in response to deviant tones, revealing for the first time preserved sensory memory processing during almost the whole night.

Subject's own name as a novel in a MMN design: a combined ERP and PET study.

With a view to elaborating a clinical tool to assess cognitive functions in brain-damaged patients, we had previously displayed characteristic patterns of ERPs (32 electrodes) in awake healthy persons in response to their own name (SON) presented as a novel in a passive oddball paradigm. In the present combined ERP and PET study, in an attempt to identify brain correlates of duration MMN and response to SON uttered by a familiar (FV) or an unknown voice (NFV), we used a block design protocol as close as possible to the aforementioned SON protocol. ERP data showed robust duration MMN and novelty P3 in response to SON similar to our previous results.

Separate neural processing of timbre dimensions in auditory sensory memory.

Timbre is a multidimensional perceptual attribute of complex tones that characterizes the identity of a sound source. Our study explores the representation in auditory sensory memory of three timbre dimensions (acoustically related to attack time, spectral centroid, and spectrum fine structure), using the mismatch negativity (MMN) component of the auditory event-related potential. MMN is elicited by a discriminable change in a sound sequence and reflects the detection of the discrepancy between the current stimulus and traces in auditory sensory memory.

Brain responses to a subject's own name uttered by a familiar voice.

Hearing one's own first name automatically elicits a robust electrophysiological response, even in conditions of reduced consciousness like sleep. In a search for objective clues to superior cognitive functions in comatose patients, we looked for an optimal auditory stimulation paradigm mobilizing a large population of neurons. Our hypothesis was that wider ERPs would be obtained in response to the subject's own name (SON) when a familiar person uttered it.

Improved prediction of awakening or nonawakening from severe anoxic coma using tree-based classification analysis.

Objective: To evaluate the utility of sensory and event-related evoked potentials for the prediction of awakening/nonawakening in severe anoxic coma and to design a decision tree helping decision for any patient in this condition.

Design: Prospective cohort study.

Setting: Clinical neurophysiology unit and intensive care unit of a French university hospital.

Mismatch negativity (MMN) in multiple sclerosis: an event-related potentials study in 46 patients.

Objective: To assess pre-attentive detection mechanisms indexed by MMN component of auditory Event-Related Potentials (ERPs) in Multiple Sclerosis (MS) patients.

Methods: 46 MS patients (mean age 43.7 years, mean disease duration 10.

Late auditory and event-related potentials can be useful to predict good functional outcome after coma.

Objective: To investigate whether late auditory and event-related potentials, and in particular N100 and mismatch negativity, together with clinical parameters, can help to predict good functional outcome in comatose patients.

Design: Prospective cohort study.

Setting: Hospital.

Predictive value of sensory and cognitive evoked potentials for awakening from coma.

Objectives: To determine the prognostic role of late auditory (N100) and cognitive evoked potentials (MMN) for awakening in a cohort of comatose patients categorized by etiology.

Methods: The authors prospectively studied a series of 346 comatose patients. Coma was caused by stroke (n = 125), trauma (n = 96), anoxia (n = 64), complications of neurosurgery (n = 54), and encephalitis (n = 7).