36 research outputs found

    Detection of Motor Cerebral Activity After Median Nerve Stimulation During General Anesthesia (STIM-MOTANA): Protocol for a Prospective Interventional Study

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    International audienceBackground Accidental awareness during general anesthesia (AAGA) is defined as an unexpected awareness of the patient during general anesthesia. This phenomenon occurs in 1%-2% of high-risk practice patients and can cause physical suffering and psychological after-effects, called posttraumatic stress disorder. In fact, no monitoring techniques are satisfactory enough to effectively prevent AAGA; therefore, new alternatives are needed. Because the first reflex for a patient during an AAGA is to move, but cannot do so because of the neuromuscular blockers, we believe that it is possible to design a brain-computer interface (BCI) based on the detection of movement intention to warn the anesthetist. To do this, we propose to describe and detect the changes in terms of motor cortex oscillations during general anesthesia with propofol, while a median nerve stimulation is performed. We believe that our results could enable the design of a BCI based on median nerve stimulation, which could prevent AAGA. Objective To our knowledge, no published studies have investigated the detection of electroencephalographic (EEG) patterns in relation to peripheral nerve stimulation over the sensorimotor cortex during general anesthesia. The main objective of this study is to describe the changes in terms of event-related desynchronization and event-related synchronization modulations, in the EEG signal over the motor cortex during general anesthesia with propofol while a median nerve stimulation is performed. Methods STIM-MOTANA is an interventional and prospective study conducted with patients scheduled for surgery under general anesthesia, involving EEG measurements and median nerve stimulation at two different times: (1) when the patient is awake before surgery (2) and under general anesthesia. A total of 30 patients will receive surgery under complete intravenous anesthesia with a target-controlled infusion pump of propofol. Results The changes in event-related desynchronization and event-related synchronization during median nerve stimulation according to the various propofol concentrations for 30 patients will be analyzed. In addition, we will apply 4 different offline machine learning algorithms to detect the median nerve stimulation at the cerebral level. Recruitment began in December 2022. Data collection is expected to conclude in June 2024. Conclusions STIM-MOTANA will be the first protocol to investigate median nerve stimulation cerebral motor effect during general anesthesia for the detection of intraoperative awareness. Based on strong practical and theoretical scientific reasoning from our previous studies, our innovative median nerve stimulation–based BCI would provide a way to detect intraoperative awareness during general anesthesia. Trial Registration Clinicaltrials.gov NCT05272202; https://clinicaltrials.gov/ct2/show/NCT05272202 International Registered Report Identifier (IRRID) PRR1-10.2196/4387

    EEG Spectral Generators Involved in Motor Imagery: A swLORETA Study

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    In order to characterize the neural generators of the brain oscillations related to motor imagery (MI), we investigated the cortical, subcortical, and cerebellar localizations of their respective electroencephalogram (EEG) spectral power and phase locking modulations. The MI task consisted in throwing a ball with the dominant upper limb while in a standing posture, within an ecological virtual reality (VR) environment (tennis court). The MI was triggered by the visual cues common to the control condition, during which the participant remained mentally passive. As previously developed, our paradigm considers the confounding problem that the reference condition allows two complementary analyses: one which uses the baseline before the occurrence of the visual cues in the MI and control resting conditions respectively; and the other which compares the analog periods between the MI and the control resting-state conditions. We demonstrate that MI activates specific, complex brain networks for the power and phase modulations of the EEG oscillations. An early (225 ms) delta phase-locking related to MI was generated in the thalamus and cerebellum and was followed (480 ms) by phase-locking in theta and alpha oscillations, generated in specific cortical areas and the cerebellum. Phase-locking preceded the power modulations (mainly alpha–beta ERD), whose cortical generators were situated in the frontal BA45, BA11, BA10, central BA6, lateral BA13, and posterior cortex BA2. Cerebellar-thalamic involvement through phase-locking is discussed as an underlying mechanism for recruiting at later stages the cortical areas involved in a cognitive role during MI

    REVIEW ARTICLE - Reconstructing cerebral palsy

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    Forty years ago, a consensual definition of the cerebral palsy concept was suggested, delineating it as a disorder of movement and posture secondary to non-progressive pathological processes that affect the immature brain. Because this concept is pragmatic and based on function, it has survived unaltered many changes in pathophysiolgical knowledge, diagnostic technology and general nosology. However, its basis has appeared to be flawed. Its main justification remains management, for which the need to meticulously select patients, define adapted objectives, design appropriate management programs and evaluate results has been increasingly recognized. Fine movement analysis using recent technologies can provide a wealth of information about neurological functioning in cerebral palsy that can serve these purposes. Specific patterns of motor organization reveal different modes of motor control in individuals with developmental motor problems. The different motor patterns reflect individual adaptation to the impairment of the central nervous system. Taken phenomenologically these patterns can contribute to the clinical approach to cerebral palsy and redefine patients groups within this framework. (J Pediatr Neurol 2004; 2(2): 57-64)

    Experimental design and electrophysiological response to electrical stimulation of mouse whiskers.

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    <p>(<b><i>A</i></b>) Animals were prepared for chronic recordings of local field potentials and unitary extracellular activity in the Purkinje cell layer of the Crus I/II area. Facial dermatomes of the whisker region were electrically or tactilely stimulated with a pair of needles under the skin (Stim.) or an air puff pulse, respectively. Sensory information comes into the Crus I/II area from the trigeminal nucleus (Tn) in the brainstem, which receives afferent signals from the trigeminal ganglion (Tg). The LFP recorded in the alert animal induced by tactile stimuli consisted of two major negative waves corresponding to trigeminal (T) and cortical (C) responses (upper trace). (<b><i>B</i></b>) In some of the recordings, the T component appeared as two separate components (N2 and N3). The figure shows superimposed LFPs (upper trace, n = 7) and the corresponding mean average (with error bars in gray at bottom) for the LFP acquired after tactile stimulation of the whisker. (<b><i>C</i></b>) Superimposed LFPs (upper trace, n = 7) and the corresponding mean average (with error bars in gray at bottom) for the LFP acquired at the same recording place shown in <i>B</i> but after electrical stimulation of the whisker. A major reproducibility of the T-related components in the superimposed traces and a decrement in the error bars in the mean average of LFP were observed after electrical stimulation in comparison to air puff stimulation. (<b><i>D</i></b>) The lower trace shows T-related components enlarged from a representative local field potential recording from the Crus II area in the Purkinje cell layer in response to a single-pulse electrical stimulation of the whisker pad (Stim. trace). Early response associated with sensory input in the cerebellum via the trigeminal nucleus is characterized by P1-N1-N2-P2-N3 components.</p

    Relationships between evoked local field potential components and Purkinje cell firing behavior.

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    <p>(<b><i>A</i></b>) Recording of spontaneous firing behavior of a Purkinje cell (PC) shows the presence of single spikes (SS) and complex spikes (CS). The presence of a CS followed by a pause in the SS firing (asterisk) identifies this neuron as a PC. (<b><i>B</i></b>) Single trials, superimposed (n = 11), show spontaneous firing before the whisker electrical stimulation (Stim) and the temporal reorganization of the firing after the stimulus. SS firing occurred at the low points of the N2 and N3 components and later. The evoked CS occurred at a latency of 9–13 ms after the stimulus onset (arrowhead). The single trace appears in color to facilitate the identification of SS and CS. (<b><i>C</i></b>) Histogram (bin size = 1 ms) of a PC recording shows the typical SS (top) and CS (bottom) response to whisker pad electrical stimulation (n = 37). After stimulus onset (arrowhead), the PC showed an initial SS burst at N2–N3 latencies, followed by a CS, followed by a silent period. (<b><i>D</i></b>) Superimposition (n = 43) of a PC recording triggered by CS (dotted line) during spontaneous firing. (<b><i>E</i></b>) Superimposition (n = 58) of the same PC presented in (<b><i>C</i></b>) in response to electrical whisker stimulation (arrowheads). The figure shows that SS and CS waveforms were preserved during whisker stimulation. (<b><i>F</i></b>) The SS latency distribution, in response to whisker pad electrical stimulation, combined from 45 PCs. The two major peaks correspond to the occurrence times of the N2 (black bars) and N3 (gray bars) postsynaptic components. Bin sizes are 0.2 ms. (<b><i>G</i></b>) Latency of the complex spike (CS) for the same population of PCs. The CS always occurred after SS evoked potentials. Bin sizes are 0.5 ms.</p