Clinical Neurophysiology

2012-03-01

Editorial Board

2012-03-01

Preliminary Announcement

2012-03-01

Serendipity in nerve excitability research

Joseph Bergmans — 2011-09-05

In single human motor nerve fibres a phase of increased threshold and latency following prolonged repetitive stimulation (H2) has been attributed, on the basis of indirect evidence, to increased activity of the sodium pump (). More direct evidence for this determinism has been obtained on frog () and mammalian () myelinated peripheral nerve fibres by showing that the underlying positive after-potential is abolished by replacing external sodium ions with lithium (which can substitute for the inward current during the action potential, but whose intracellular accumulation does not activate the sodium pump).

The mismatch negativity (MMN) – A unique window to disturbed central auditory processing in ageing and different clinical conditions

2011-12-14

Highlights: ► The mismatch negativity (MMN) indexes different types of central auditory abnormalities in different neuropsychiatric, neurological, and neurodevelopmental disorders. ► The diminished amplitude/prolonged peak latency observed in patients usually indexes decreased auditory discrimination. ► An MMN deficit may also index cognitive and functional decline shared by different disorders irrespective of their specific aetiology and symptomatology. ► MMN deficits index deficient N-methyl-d-aspartate (NMDA) receptor function affecting memory-trace formation and hence cognition in different disorders.Abstract: In this article, we review clinical research using the mismatch negativity (MMN), a change-detection response of the brain elicited even in the absence of attention or behavioural task. In these studies, the MMN was usually elicited by employing occasional frequency, duration or speech-sound changes in repetitive background stimulation while the patient was reading or watching videos. It was found that in a large number of different neuropsychiatric, neurological and neurodevelopmental disorders, as well as in normal ageing, the MMN amplitude was attenuated and peak latency prolonged.Besides indexing decreased discrimination accuracy, these effects may also reflect, depending on the specific stimulus paradigm used, decreased sensory-memory duration, abnormal perception or attention control or, most importantly, cognitive decline. In fact, MMN deficiency appears to index cognitive decline irrespective of the specific symptomatologies and aetiologies of the different disorders involved.

The yield of routine electroencephalography in the detection of incidental nonconvulsive status epilepticus – A prospective study

Stefan Seidel, Susanne Aull-Watschinger, Ekaterina Pataraia — 2011-07-20

Highlights: ► Prospective study on the incidence of NCSE. ► Half of NCSE unsuspected to treating physicians. ► Unsuspected NCSE mostly in patients without significant reduction of consciousness.Abstract: Objective: Diagnosis of NCSE is challenging, because the clinical presentation ranges from minimally altered mental status to coma without tonic–clonic activity. According to the largest retrospective study to date the incidence of NCSE is about 0.2%.Methods: We prospectively investigated electroencephalography (EEG) recordings of 2514 consecutive patients that were referred to the Electrophysiology Unit of Department of Neurology, Vienna General Hospital between November 2009 and February 2011 (i.e. 16months).Results: The incidence of NCSE in our study population was 0.8%, i.e. the EEG of 19 patients fulfilled the criteria of NCSE. In 53% of these patients the NCSE was not suspected by treating physicians. A severely reduced level of consciousness was found in 78% of patients with a suspected NCSE and in 30% of patients with an unsuspected NCSE, although the results were not statistically significant (p=0.081). The delay between the admission to the hospital and diagnosis ranged between 0 and 51days.Conclusions: NCSE was an unsuspected finding in more than half of the patients. Consciousness was severely impaired in only one third of these patients.Significance: These results highlight the importance of urgent EEG for the diagnosis of NCSE in patients even without significant impairment of consciousness.

Do sphenoidal electrodes aid in surgical decision making in drug resistant temporal lobe epilepsy?

2011-08-26

Highlights: ► We evaluated the utility of spheniodal electrodes (SPh) in surgical decision making in drug resistant temporal lobe epilepsy. ► We compared the prevalence of interictal and ictal EEG findings over the conventional scalp and SPh electrodes. ► In nearly one-third of our patients, SPh electrodes revealed EEG findings which were not evident in conventional scalp electrodes. ► Based on SPh findings, 25% of our patients with bilateral mesial temporal sclerosis could be selected for surgery. ► Used judiciously, SPh minimizes the need for invasive EEG monitoring in mesial temporal lobe epilepsy surgical candidates.Abstract: Objective: The utility of sphenoidal electrodes (SPh) in analyzing interictal epileptiform discharges (IEDs) and ictal electrography remains controversial, despite its widespread use.Methods: One hundred and twenty-two consecutive patients with presumed temporal lobe epilepsy (TLE) who underwent presurgical evaluation were prospectively studied. SPh and Silverman’s electrodes were placed, in addition to routine electrodes in 10–20 international system. IEDs and ictal electroencephalography (EEG) were analyzed separately in bipolar and referential montages. The proportion of patients selected for surgery after adjusting for SPh placement based on the earlier ictal onset and IEDs were analyzed.Results: Of the 8701 IEDs in SPh, only 65% were seen over the scalp bipolar montage; 1392 (16%) IEDs were confined to SPh electrodes, and were not seen at scalp bipolar montage (p<0.001). Spike amplitudes were highest at SPh (p<0.001). Of the 592 seizures analyzed, 62 (61%) had simultaneous SPh and scalp onset, while in 26 (25%) SPh onset preceded the scalp.Conclusions: Out of the 35 patients with unilateral mesial temporal sclerosis (MTS) with additional neocortical changes and/or non-lateralized bitemporal IEDs and/or diffuse ictal onset (group 1), 27 were selected for surgery (77%). About 7% was selected for surgery in this group by SPh placement. Also, in patients with bilateral MTS (group 2), 25% (5/20) were chosen for anterior temporal lobectomy, SPh provided an additional benefit in 11% (p<0.001). Patients with normal magnetic resonance imaging (group 3) and temporal plus epilepsy (group 4) had a lower surgical yield, only 12% and 9.5% could undergo surgery. They were denied surgical candidacy with SPh (p<0.001).Significance: One-third of patients after SPh placement were selected for resective surgery obviating the need for invasive monitoring. The maximum yield was noted in unilateral MTS (associated with additional neocortical features or non-lateralized bilateral temporal interictal IEDs or diffuse ictal onset in scalp EEG) and in bilateral MTS. Those with normal MRI/temporal plus epilepsy could be excluded from direct resective surgery.

Quantification and localization of EEG interictal spike activity in patients with surgically removed epileptogenic foci

2011-09-07

Highlights: ► This is a clinical study comparing the accuracy of two available methods for epileptic spike source localization using a gold standard of surgical outcomes in a wide epilepsy surgery series. ► The importance of selecting the appropriate time window during spike onset for localization is demonstrated. ► The sensitivity and specificity of source localization to the likely location of the epileptogenic cortex is assessed.Abstract: Objective: To demonstrate if interictal spike activity was localized within the resected area in surgically treated epilepsy patients; and if there is correspondence between the degree of localization and improvement after surgery.Methods: We analyzed long-term EEGs from 34 patients. Interictal spikes were grouped in clusters and averaged according to morphology and topography. The relative contribution of each cluster to the total number of spikes in each patient was estimated. Dipole and distributed EEG source localization of each cluster was made. The percentage of spike activity localized within the site of resection (SR) during the onset was estimated. The relationship between the percentage of activity within SR and the surgery outcome was assessed.Results: Fourteen patients had 90–100% of spikes within SR, 9 had 50–89%. Most patients with more than 50% of activity localized within SR were seizure free, while the 5 patients who had all activity localized outside SR were not seizure free.Conclusions: Localization of clusters containing the largest quantity of interictal spikes during onset generally corresponded to the likely location of the epileptogenic cortex.Significance: Computer-assisted EEG source localization with our methodology can be a useful adjunct for the evaluation of candidates for epilepsy surgery.

Seizure clusters and adverse events during pre-surgical video-EEG monitoring with a slow anti-epileptic drug (AED) taper

2011-09-15

Highlights: ► The study evaluated efficacy and safety of pre-surgical video-EEG monitoring with a slow anti-epileptic drug (AED) taper. ► Seizure clusters are frequent when AEDs are withdrawn. ► Serious adverse events are rare when monitoring is performed in a highly supervised setting.Abstract: Objective: To evaluate the efficiency and safety of pre-surgical video-EEG monitoring with a slow anti-epileptic drug (AED) taper and a rescue benzodiazepine protocol.Methods: Fifty-four consecutive patients with refractory focal epilepsy who underwent pre-surgical video-electroencephalography (EEG) monitoring during the year 2010 were included in the study. Time to first seizure, duration of monitoring, incidence of 4-h and 24-h seizure clustering, secondarily generalised tonic–clonic seizures (sGTCS), status epilepticus, falls and cardiac asystole were evaluated.Results: A total of 190 seizures were recorded. Six (11%) patients had 4-h clusters and 21 (39%) patients had 24-h clusters. While 15 sGTCS were recorded in 14 patients (26%), status epilepticus did not occur and no seizure was complicated with cardiac asystole. Epileptic falls with no significant injuries occurred in three patients. The mean time to first seizure was 3.3days and the time to conclude video-EEG monitoring averaged 6days.Conclusion: Seizure clustering was common during pre-surgical video-EEG monitoring, although serious adverse events were rare with a slow AED tapering and a rescue benzodiazepine protocol.Significance: Slow AED taper pre-surgical video-EEG monitoring is fairly safe when performed in a highly specialised and supervised hospital setting.

Rhinal–hippocampal interactions during déjà vu

2011-09-19

Highlights: ► The phenomenon of déjà vu is caused by acute disturbance of mnemonic systems of the medial temporal lobe (MTL). ► In epileptic patients investigated with intracerebral electrodes, déjà vu can be more readily induced by stimulation of the rhinal cortices than the hippocampus. ► This study is the first to report the signal correlations of intracerebral EEG signals between MTL structures during déjà vu, demonstrating large collaboration between these brain structures.Abstract: Objective: The phenomenon of ‘déjà vu’ is caused by acute disturbance of mnemonic systems of the medial temporal lobe (MTL). In epileptic patients investigated with intracerebral electrodes, déjà vu can be more readily induced by stimulation of the rhinal cortices (RCs) than the hippocampus (H). Whether déjà vu results from acute dysfunction of the familiarity system alone (sustained by RC) or from more extensive involvement of the MTL region (including H) is debatable.Methods: We analysed the synchronisation of intracerebral electroencephalography (EEG) signals recorded from RC, H and amygdala (A) in epileptic patients in whom déjà vu was induced by electrical stimulation.EEG signal correlations (between signals from RC, A and H) were evaluated using a nonlinear regression.Results: In comparison with RC stimulations that did not lead to déjà vu (DV−), stimulations triggering déjà vu (DV+) were associated with increased broadband EEG correlation (p=0.01). Changes in correlations were significantly different in the theta band for RC–A (p=0.007) and RC–H (p=0.01) and in the beta band for RC–H (p=0.001) interactions.Conclusion: Déjà vu is associated with increased EEG signal correlation between MTL structures.Significance: Results are in favour of a mechanism involving transient co-operation between various MTL structures, not limited to RC alone.

P300 in neglect

Styrmir Saevarsson, Árni Kristjánsson, Michael Bach, Sven P. Heinrich — 2011-08-16

Highlights: ► Reduced P300 to contralesional targets relative to ipsilesional targets in neglect. ► P300 amplitudes correlate with scores and time in standard neglect tests. ► Results suggest a link between attentional dysfunction and impaired stimulus processing.Abstract: Objective: Attentional deficits have been thought to underlie hemispatial neglect. The present study investigates this using the P300 component of the event-related potential, which is assumed to reflect the allocation of attention.Methods: We recorded the P300 and oddball detection performance from patients with neglect. Infrequent targets appeared either in the affected contralesional or the unaffected ipsilesional visual hemifield.Results: Contralesional targets produced weaker average P300 responses than ipsilesional ones, but stronger responses than when only distractors were presented. In the affected hemifield, the difference in P300 amplitude between identified and missed targets was correlated with the miss rate. The number of missed contralesional targets for a given participant was positively correlated with the time required for completion of standard neglect tests.Conclusions: The P300 not only reflects a general attentional impairment in neglect, but also varies as a function of the participants’ awareness of individual stimuli.Significance: The findings reflect an important link between attentional dysfunction and impaired stimulus processing in neglect and extinction.

Finding the right control: The mismatch negativity under investigation

Philipp Ruhnau, Björn Herrmann, Erich Schröger — 2011-08-12

Highlights: ► The ERP components N1 and MMN were measured in oddball and random control blocks as well as in a new cascadic control sequence. ► The cascadic control sequence was designed as a conceptual and methodological refinement of previous control approaches. ► We aimed to improve the estimation of N1-specific refractoriness effects in deviants of an oddball block. ► We found the new cascadic control design to be the most reasonable control for oddball deviants. ► The cascadic control design enables the investigation of the MMN without overestimating frequency-specific refractory states.Abstract: Objective: When investigating auditory perceptual regularity processing, mismatch negativity (MMN) is commonly used. MMN is computed as a difference signal between the event-related potentials (ERPs) elicited by repeated standard tones and rarely occurring deviant tones. This procedure leads to an underestimation of the N1 component elicited by standards compared to the N1 to deviants which might affect the MMN. Consequently, a random control design was previously introduced. This design, however, overestimates the N1 to the deviant. Here, we developed a new paradigm that avoids previous drawbacks.Methods: We designed a regular cascadic sequence as a control to the deviant. ERPs were measured while presenting conventional oddball blocks (standards, deviants), random control blocks and a cascadic control block.Results: MMN was observed in each difference signal. Regarding the N1, standards elicited smallest amplitudes. The N1 for the deviant and the cascadic control was comparable. The largest N1 was elicited by the random control.Conclusion: Standards underestimate N1 refractoriness effects in the responses to deviants, while random control tones overestimate. Cascadic control tones, however, provide a reasonable estimation for the N1.Significance: The new cascadic control design is suitable to investigate auditory perceptual regularity processes while controlling for N1 refractoriness effects.

Foveal and parafoveal spatial attention and its impact on the processing of facial expression: An ERP study

Albertus A. Wijers, Stella Banis — 2011-09-02

Highlights: ► Fearful and neutral faces were presented at attended/unattended foveal and parafoveal locations. ► Spatial attention enhanced P1/N1 ERP components at both locations. ► Expression effects were earlier for attended foveal than parafoveal stimuli, and present for unattended parafoveal faces but absent for unattended foveal faces.Abstract: Objective: The aim was to investigate the effects of spatial attention, stimulus location, and emotional expression on the processing of face stimuli.Methods: Healthy volunteers performed two sustained attention tasks, focusing their attention on either fixation (foveal location) or on a location several degrees above fixation (parafoveal location). Photographs of faces with either a neutral or a fearful expression were presented randomly at one of these locations. Event-related potentials were recorded in response to the face stimuli.Results: Spatial attention modulated the early P1 and N1 components for both foveally and parafoveally presented stimuli. Emotional expression effects already occurred at the P1 stage in response to attended foveal stimuli, but only arose from 220ms post-stimulus onwards in response to attended parafoveal stimuli. When faces were unattended, emotional expression effects were still present for parafoveal stimuli, whereas they were completely absent for foveal stimuli.Conclusions: The modulations of the P1/N1 components by fearful faces are due to an early sensory modulation of extrastriate generators, and reflect an enhanced allocation of attention to threat-related stimuli.Significance: Future studies should take into account the possibility that spatial attention effects and effects of emotional expression processing are different for different positions in the visual field.

Reorganization of multi-muscle and joint withdrawal reflex during arm movements in post-stroke hemiparetic patients

2011-08-09

Highlights: ► In a broader motor context these findings represent the spinal neuropathophysiological correlate of the movement abnormalities observed in hemiparetic patients. ► This study show a maladaptive behavior of the spinal cord during arm movements in stroke patients determined by new functional brain–spinal cord connections. ► This finding indicates a marked plastic rearrangement of the spinal cord which partially loses its capacity for functional modulation by descending motor pathways during a motor task.Abstract: Objectives: To investigate the behavior of the nociceptive withdrawal reflex (NWR) in the upper limb during reaching and grasping movements in post-stroke hemiparetic patients.Methods: Eight patients with chronic stroke and moderate motor deficits were included. An optoelectronic motion analysis system integrated with a surface EMG machine was used to record the kinematic and EMG data. The NWR was evoked through a painful electrical stimulation of the index finger during a movement which consisted of reaching out, picking up a cylinder, and returning it to the starting position.Results: We found that: (i) the NWR is extensively rearranged in hemiparetic patients, who were found to present different kinematic and EMG reflex patterns with respect to controls; (ii) patients partially lose the ability to modulate the reflex in the different movement phases; (iii) the impairment of the reflex modulation occurs at single-muscle, single-joint and multi-joint level.Conclusions: Patients with chronic and mild-moderate post-stroke motor deficits lose the ability to modulate the NWR dynamically according to the movement variables at individual as well as at multi-muscle and joint levels.Significance: The central nervous system is unable to use the NWR substrate dynamically and flexibly in order to select the muscle synergies needed to govern the spatio–temporal interaction among joints.

Short-latency crossed spinal responses are impaired differently in sub-acute and chronic stroke patients

P.W. Stubbs, J.F. Nielsen, T. Sinkjær, N. Mrachacz-Kersting — 2011-08-12

Highlights: ► Short-latency crossed spinal interlimb reflexes are impaired differently in sub-acute and chronic stroke patients. ► The reflexes are impaired from the non-paretic to paretic and paretic to non-paretic extremities in both patient groups suggesting that projections to the paretic and non-paretic extremities modulate the response. ► The inappropriate modulation of these reflexes may result in an inability to appropriately modify the muscle activity of the opposite leg subsequently reducing the ability to quickly avoid obstacles (which may contribute to falls).Abstract: Objective: Investigate if patients with supraspinal lesions have impaired interlimb spinal reflex pathways. The short-latency crossed spinal response will be investigated during sitting from the non-paretic to paretic and paretic to non-paretic extremities at different stimulation intensities in chronic and sub-acute stroke patients.Methods: The ipsilateral tibial nerve of the paretic and non-paretic extremities were stimulated at motor threshold, 35% M-max and 85% M-max of the ipsilateral soleus while the contralateral soleus was contracted from 5% to 15% of the maximum voluntary contraction of the paretic soleus.Results: Chronic patients (from both extremities) had significantly less prominent inhibitory responses than healthy controls (post hoc tests: P .05). Some sub-acute patients had significantly more variable responses than chronic patients and healthy controls (P<.001–P⩽.05).Conclusions: Short-latency interlimb reflexes are impaired differently in sub-acute vs. chronic patients, are impaired from the non-paretic and paretic extremity, and abnormal when compared to healthy controls.Significance: The inappropriate coordination could result in an inability to quickly avoid obstacles following a mechanical disturbance to the ipsilateral extremity. It also indicates that bilateral descending projections affect the response.

Mu rhythm, visual processing and motor control

Magdalena Sabate, Catalina Llanos, Enrique Enriquez, Manuel Rodriguez — 2011-08-16

Highlights: ► Visual stimuli induce an early phase-locked Mu-rhythm in the sensorimotor cortex which is task-dependent. ► Visual stimuli can induce a persistent decrease of non-phase-locked Mu-rhythm. ► Mu-rhythm can both inhibit and promote information processing in the sensorimotor cortex.Abstract: Objective: The Mu-rhythm has been proposed as both an inhibitor (“idling hypothesis”) and as a promoter (“processing hypothesis”) of information processing in the primary sensory-motor cortex (SM-C). We tested these possibilities by analyzing the phase-locked and non-phase-locked Mu response during the execution of a visual–motor task.Methods: EEG was recorded in 13 subjects during the visual presentation of an arrow which indicated the direction of the finger motion to be executed after the presentation of a second stimulus. The EEG activity in the α-range (Mu-α) and β-range was evaluated by a method which segregated the phase-locked and the non-phase-locked response. The event-related Mu-response observed during this task was compared with that computed when the subjects saw the same arrow-stimuli but did not perform any task (passive test).Results: Visual stimuli induced a phase-locked α-oscillation which began ≈50ms after the stimulus onset and persisted for about 150–200ms. This response was much higher when stimuli were used for motion planning than when they were passively observed, and was more marked in the α-range than in the β-range. The phase-locked response was followed by a persistent decrease of the non-phase-locked Mu-activity similar to that previously reported with the event-related desynchronization/synchronization method.Conclusions: The Mu-wave is not a single phenomenon. It was segregated here into two components, one with an early and short-lasting phase locked-response to visual stimuli, which increased during the task execution, and the other without phase-locked responses which persistently decreased during the task execution.Significance: Present data suggest that Mu-activity performs a double action, increasing the information processing of one task (according to the “processing hypothesis”) and decreasing the computation of other potentially interfering tasks (according to the “idling hypothesis”), with task selection being achieved by choosing their phase-association to the Mu-wave.

Limb segment vibration modulates spinal reflex excitability and muscle mRNA expression after spinal cord injury

2011-10-03

Highlights: ► Vertical limb oscillations (vibration) resulted in a predominant inhibition of H-reflex and post-activation depression mechanism in both SCI and healthy control groups. ► Microarray analysis revealed that a short-term limb segment vibration had significant effects on genes associated with synaptic plasticity. ► These findings highlight the possibility that long-term vibration training may promote spinal neuronal plasticity in individuals with chronic SCI.Abstract: Objective: We investigated the effect of various doses of vertical oscillation (vibration) on soleus H-reflex amplitude and post-activation depression in individuals with and without SCI. We also explored the acute effect of short-term limb vibration on skeletal muscle mRNA expression of genes associated with spinal plasticity.Methods: Six healthy adults and five chronic complete SCI subjects received vibratory stimulation of their tibia over three different gravitational accelerations (0.3g, 0.6g, and 1.2g) at a fixed frequency (30Hz). Soleus H-reflexes were measured before, during, and after vibration. Two additional chronic complete SCI subjects had soleus muscle biopsies 3h following a single bout of vibration.Results: H-reflex amplitude was depressed over 83% in both groups during vibration. This vibratory-induced inhibition lasted over 2min in the control group, but not in the SCI group. Post-activation depression was modulated during the long-lasting vibratory inhibition. A single bout of mechanical oscillation altered mRNA expression from selected genes associated with synaptic plasticity.Conclusions: Vibration of the lower leg inhibits the H-reflex amplitude, influences post-activation depression, and alters skeletal muscle mRNA expression of genes associated with synaptic plasticity.Significance: Limb segment vibration may offer a long term method to reduce spinal reflex excitability after SCI.

Stretch reflex responses in Complex Regional Pain Syndrome-related dystonia are not characterized by hyperreflexia

2011-09-07

Highlights: ► Disinhibition of reflex pathways due to central sensitization may cause dystonia of CRPS. ► No significant differences in stretch reflex responses were found between CRPS-patients with dystonia and controls when compared at equal percentage of maximum voluntary contraction torque. ► Significantly smaller stretch reflex responses were found in CRPS-patients with dystonia in respect to controls when compared at similar absolute torque.Abstract: Objective: To evaluate if hyperreflexia (exaggerated reflexes) due to disinhibition is associated with dystonia in Complex Regional Pain Syndrome (CRPS).Methods: Stretch reflexes at the wrist were assessed in healthy controls (n=10) and CRPS-patients with dystonia (n=10). Subjects exerted a wrist flexion torque of 5% of maximum voluntary contraction torque (TMVC) to a manipulandum which applied ramp-and-hold stretches to the wrist flexors. Since reflex responses scale with background contraction, controls additionally performed the task at 1% and 3% TMVC to attain similar torques as patients who have reduced TMVC.The M1 onset and the magnitudes of the short latency M1 and long latency M2 were assessed using the electromyographic signals (EMG) of the flexor carpi radialis. EMG of the extensor carpi radialis was recorded to monitor cocontraction.Results: Compared to controls, patients had a substantially reduced TMVC. Ramp velocity had a significant effect on M1 onset time and magnitude.Conclusions: Since M1 magnitude decreased with flexion torque, no significant difference was found between patients and controls at 5% TMVC, while comparison at similar absolute torques (controls at 1% TMVC) resulted in significantly smaller M1 magnitudes for patients with dystonia.Significance: This study suggests that CRPS-patients with dystonia are not hyperreflexive.

The role of proprioception in the consolidation of ipsilateral 1Hz-rTMS effects on motor performance

2011-09-19

Highlights: ► We demonstrated that muscle vibration, if applied after 1Hz-repetitive transcranial magnetic stimulation (1Hz rTMS) on ipsilateral M1, can interact with rTMS cortical effects. ► Subjects who voluntarily executed a finger opposition task after rTMS presented motor performance changes lasting till 30min after rTMS as did subjects who received muscle vibration after rTMS protocol. ► Muscle vibration might be used in a rehabilitative setting to consolidate rTMS effects in patients with sensory pathways preserved.Abstract: Objectives: The aim of the present work is to investigate whether the longlasting effect of the ipsilateral primary motor cortex (ipsiM1) 1Hz-repetitive transcranial magnetic stimulation (1Hz-rTMS) on motor performance can be modulated by subsequent engagement of the sensorimotor system through muscle vibration.Methods: Twenty-one subjects were divided into three groups: MOVEMENT group performed the 1min-finger opposition task before (PRE), immediately after (POST0), 15min (POST15) and 30min after (POST30) the 1Hz-rTMS on ipsiM1; the REST and VIBRATION groups performed the finger opposition task only at PRE and POST30. However, in the VIBRATION group at POST0 and POST15 the right flexor carpi radialis (FCR) was vibrated for 1min. Motor performance was recorded at PRE and POST30.Results: The MOVEMENT and VIBRATION groups showed at POST30 similar and significant changes in motor performance. A decrease in movement time and an increase in touch duration with no change in the ability to follow the metronome cue were observed. Motor performance did not change in the REST group at POST30.Conclusions: These findings suggest that vibration of FCR can interact with rTMS cortical effects in a similar way to the voluntary movement.Significance: Muscle vibration might be used in a rehabilitative setting to consolidate rTMS effects in patients with sensory pathways preserved.

Increased baseline temperature improves the acquisition of contact heat evoked potentials after spinal cord injury

J.L.K. Kramer, J. Haefeli, A. Curt, J.D. Steeves — 2011-10-03

Highlights: ► Increased skin surface baseline temperature increases the N2P2 amplitude of contact heat evoked potentials. ► The effect of an increased baseline on N2P2 amplitude can be attributed in part to shortening the stimulus duration and improving the synchronization of the afferent volley. ► After spinal cord injury, varying the baseline temperature improved the perception of noxious stimuli and acquisition of evoked potentials in dermatomes with absent or diminished sensation according to conventional sensory testing methods (i.e. pinprick testing and 35°C baseline contact heat evoked potentials).Abstract: Objective: To investigate the effect of increasing the skin surface baseline temperature for contact heat evoked potentials (CHEPs).Methods: CHEPs were studied in healthy subjects and subjects with chronic cervical spinal cord injury (SCI) using a conventional 35°C (condition 1) or increased 42–45°C baseline temperature (condition 2). A third condition was used to standardize the contact heat stimulus duration from the different baseline temperatures. Changes in peak latency and N2P2 amplitude of the CHEPs and rating of perceived intensity were examined between conditions.Results: In healthy subjects, increasing the baseline temperature for contact heat stimulation significantly increased the rating of perceived intensity (conditions 2 and 3), as well as the amplitude of CHEPs (condition 2 only). Following SCI, an increased baseline temperature facilitated perception of contact heat stimulation and evoked potentials could be recorded from dermatomes that were insensitive to contact heat from a conventional baseline temperature.Conclusions: Enhancing the acquisition of CHEPs can be achieved by increasing the baseline temperature. This effect can be attributed, in part, to shortening the stimulation duration.Significance: After SCI, increasing the baseline temperature for CHEPs in dermatomes with absent or diminished sensation improved the neurophysiological resolution of afferent sparing.

Sex differences in auditory subcortical function

Jennifer Krizman, Erika Skoe, Nina Kraus — 2011-08-22

Highlights: ► Male and female young adults have measurably different neural responses to speech; to the fast acoustic components of speech, female responses are generally earlier and more robust than male responses. ► The differences observed between males and females in the nervous system’s response to speech parallel those previously reported for poor, relative to good, readers. ► These sex differences provide a baseline for interpreting the higher incidence of language impairment in males, and the neural deficits associated with these disorders.Abstract: Objective: Sex differences have been demonstrated in the peripheral auditory system as well as in higher-level cognitive processing. Here, we aimed to determine if the subcortical response to a complex auditory stimulus is encoded differently between the sexes.Methods: Using electrophysiological techniques, we assessed the auditory brainstem response to a synthesized stop-consonant speech syllable [da] in 76 native-English speaking, young adults (38 female). Timing and frequency components of the response were compared between males and females to determine which aspects of the response are affected by sex.Results: A dissimilarity between males and females was seen in the neural response to the components of the speech stimulus that change rapidly over time; but not in the slower changing, lower frequency information in the stimulus. We demonstrate that, in agreement with the click-evoked brainstem response, females have earlier peaks relative to males in the subcomponents of the response representing the onset of the speech sound. In contrast, the response peaks comprising the frequency-following response, which encode the fundamental frequency (F0) of the stimulus, as well as the spectral amplitude of the response to the F0, is not affected by sex. Notably, the higher-frequency elements of the speech syllable are encoded differently between males and females, with females having greater representation of spectrotemporal information for frequencies above the F0.Conclusions: Our results provide a baseline for interpreting the higher incidence of language impairment (e.g. dyslexia, autism, specific language impairment) in males, and the subcortical deficits associated with these disorders.Significance: These results parallel the subcortical encoding patterns that are documented for good and poor readers in that poor readers differ from good readers on encoding fast but not slow components of speech. This parallel may thus help to explain the higher incidence of reading impairment in males compared to females.

Evoked potentials and quantitative thermal testing in spinal cord injury patients with chronic neuropathic pain

2011-08-18

Highlights: ► Patients with spinal cord injury (SCI) and chronic neuropathic pain can demonstrate generalized pain perception changes at or above lesion level. ► Contact heat evoked potentials and quantitative thermal testing may provideuseful information regarding patients with spinal cord injury and neuropathic pain. ► Alteration in the processing of somatosensory inputs from dermatomes rostral to the injury level in SCI patients with neuropathic pain (NP) may contribute to the understanding of the mechanisms underlying NP and secondary changes to neuropathic pain in SCI.Abstract: Objective: Neuropathic pain (NP) is a common symptom following spinal cord injury (SCI). NP may be associated with altered processing of somatosensory pathways in dermatomes rostral to the injury level. To explore this possibility, the characteristics of contact heat evoked potentials (CHEPs) and quantitative thermal testing (QTT) were studied at and above the lesion level in SCI patients with NP. The goal was to determine processing abnormalities correlated with data from clinical evaluations.Methods: Thirty-two subjects with chronic NP, 22 subjects without NP and 16 healthy control subjects were studied. Warm and heat pain thresholds were determined both at and above SCI level. CHEPs were recorded above SCI level and subjects rated their perception of evoked heat pain using a numerical rating scale.Results: CHEPs were not different between the three groups. Evoked pain perception in SCI subjects with NP was significantly higher than in SCI subjects without NP and healthy controls. Heat pain threshold was significantly lower in subjects with NP in comparison to both groups.Conclusions: Our findings indicate that processing of somatosensory inputs from dermatomes rostral to the injury level is abnormal in SCI subjects with NP.Significance: SCI somatosensory processing alteration may contribute to the understanding of the mechanisms underlying NP and secondary changes to NP in SCI.

Tonic pain and continuous EEG: Prediction of subjective pain perception by alpha-1 power during stimulation and at rest

Rony-Reuven Nir, Alon Sinai, Ruth Moont, Eyal Harari, David Yarnitsky — 2011-09-02

Highlights: ► Alpha-1 power, obtained at the temporal scalp bilaterally during both resting-state and the application of noxious stimulation, predicts individual experiences of tonic pain. ► Alpha-1 power may serve as a direct, objective and experimentally stable measure of subjective perception of tonic pain. ► The association of alpha-1 power with subjective responsiveness to prolonged pain may facilitate a better understanding of the mechanisms underlying the processing of tonic nociceptive stimulation.Abstract: Objective: Pain neurophysiology has been chiefly characterized via event-related potentials (ERPs), which are exerted using brief, phase-locked noxious stimuli. Striving for objectively characterizing clinical pain states using more natural, prolonged stimuli, tonic pain has been recently associated with the individual peak frequency of alpha oscillations. This finding encouraged us to explore whether alpha power, reflecting the magnitude of the synchronized activity within this frequency range, will demonstrate a corresponding relationship with subjective perception of tonic pain.Methods: Five-minute-long continuous EEG was recorded in 18 healthy volunteers under: (i) resting-state; (ii) innocuous temperature; and (iii) psychophysically-anchored noxious temperature. Numerical pain scores (NPSs) collected during the application of tonic noxious stimuli were tested for correlation with alpha-1 and alpha-2 power.Results: NPSs and alpha power remained stable throughout the recording conditions (Ps⩾0.381). In the noxious condition, alpha-1 power obtained at the bilateral temporal scalp was negatively correlated with NPSs (Ps⩽0.04). Additionally, resting-state alpha-1 power recorded at the bilateral temporal scalp was negatively correlated with NPSs reported during the noxious condition (Ps⩽0.038).Conclusions: Current findings suggest alpha-1 power may serve as a direct, objective and experimentally stable measure of subjective perception of tonic pain. Furthermore, resting-state alpha-1 power might reflect individuals’ inherent tonic pain responsiveness.Significance: The relevance of alpha-1 power to tonic pain perception may deepen the understanding of the mechanisms underlying the processing of prolonged noxious stimulation.

Reference values for voluntary and stimulated single-fibre EMG using concentric needle electrodes: A multicentre prospective study

2011-09-02

Highlights: ► The reference values for both voluntary and stimulated concentric SFEMG in the EDC and frontal muscles were constructed. ► The reference values obtained in this study were larger than those reported previously for concentric needles. ► Appropriate definitions of the percentile and cut-off values were discussed.Abstract: Objective: The aim of this study is to establish reference values for single-fibre electromyography (SFEMG) using concentric needles in a prospective, multicentre study.Methods: Voluntary or stimulated SFEMG at the extensor digitorum communis (EDC) or frontalis (FRO) muscles was conducted in 56–63 of a total of 69 normal subjects below the age of 60years at six Japanese institutes. The cut-off values for mean consecutive difference (MCD) of individual potentials were calculated using +2.5 SD or 95% prediction limit (one-tail) of the upper 10th percentile MCD value for individual subjects.Results: The cut-off values for individual MCD (+2.5 SD) were 56.8μs for EDC-V (voluntary SFEMG for EDC), 58.8μs for EDC-S (stimulated SFEMG for EDC), 56.8μs for FRO-V (voluntary SFEMG for FRO) and 51.0μs for FRO-S (stimulated SFEMG for FRO). The false positive rates using these cut-off values were around 2%.Conclusions: The +2.5 SD and 95% prediction limit might be two optimal cut-off values, depending on the clinical question. The obtained reference values were larger than those reported previously using concentric needles, but might better coincide with conventional values.Significance: This is the first multicentre study reporting reference values for SFEMG using concentric needles. The way to determine cut-off values and the statistically correct definition of the percentile were discussed.

Quantification of motor unit action potential energy

Geoffrey L. Sheean — 2011-09-07

Highlights: ► Motor units generate force so the energy content of a MUAP is of interest. ► MUAP energy follows an exponential distribution, suggesting it directly reflects the force-generating capacity of the motor unit. ► MUAP energy correlates strongly with the MUAP Size Index.Abstract: Objective: Motor unit action potentials (MUAPs) recorded by needle electrode reflect the functional state of the motor unit and its force-generating capacity, and are usually described morphologically (e.g. amplitude, duration). However, since the purpose of motor unit activation is force generation, MUAP energy seems a more physically meaningful measurement.Methods: MUAPs were obtained by multi-MUAP decomposition of real interference patterns taken from human patients with neurological diseases. The energy content of each MUAP was measured from a time–frequency representation (TFR), specifically the Choi–Williams distribution, and compared with the standard MUAP morphological measure, the Size Index. The sample included normal, neurogenic, and myopathic MUAPs, from 11 patients.Results: There is an exponential distribution of energy within a sample of MUAPs and a strong exponential relationship between the Size Index and MUAP energy was observed.Conclusions: The energy content of a MUAP can be quantified and corresponds very well with the current quantitative standard. Energy is a possible addition to MUAP quantification.Significance: MUAPs could be classified as having normal, large (neurogenic), or low (myopathic) energy. MUAP energy has direct physical and physiological meaning that reflects the force-generating capacity of the motor unit. Time–frequency analysis could also be used to study the specific frequency content of MUAPs and the energy of MUAPs within an interference pattern, without the need for decomposition.

Neuromuscular ultrasound in the diagnosis of focal neuropathies superimposed on polyneuropathy: A case report

Preet S. Chahal, Waqas Sohail, Michael S. Cartwright — 2011-08-11

Neuromuscular ultrasound is an emerging technique for the diagnosis of a variety of nerve and muscle conditions, and it has proven particularly helpful in the evaluation of focal neuropathies (). In these conditions, focal enlargement of nerve cross-sectional area can be detected and quantified with ultrasound. One of the more difficult diagnoses to establish with electrodiagnostic studies is that of a focal neuropathy superimposed on a polyneuropathy. In our lab, we have found ultrasound to be a very helpful complement to electrodiagnostic studies in this type of situation, and the following case illustrates its use in the diagnosis of several focal neuropathies in an individual with polyneuropathy.

Corrigendum to “Event-related brain potential modulation in patients with severe brain damage” [Clin. Neurophysiol. 122 (2011) 719–724]

M. Cavinato, C. Volpato, S. Silvoni, M. Sacchetto, A. Merico, F. Piccione — 2011-09-02

The authors regret that an error appeared in the ‘Methods’ section of the ‘Abstract’. The correction is as follows: The patients in vegetative state were 11 and the MCS patients were 6.

1. Neuromodulation of motor learning in health and after stroke

U. Ziemann — 2012-03-01

Ischemic cerebral stroke is the leading cause of long-term disability among adults in industrialized countries. A fundamental but still not sufficiently solved question is how to improve disability after stroke. One approach to this unmet medical need is to explore ways of modifying synaptic plasticity and learning along a translational pathway from basic neuroscience over healthy human subjects to stroke patients [Ziemann et al. 2006, Neurorehabil Neural Repair; 20: 243–51]. This presentation will review evidence for this translational pathway on how pharmacological treatment or brain stimulation modulates synaptic plasticity (long-term plasticity, LTP) and motor learning, which is thought to be an LTP-dependent process. The focus will be on drugs that are agonists or antagonists at the NMDA and GABA receptors, on neuromodulating drugs that modify activity in the dopaminergic, noradrenergic, serotonergic and cholinergic systems, and on novel non-invasive brain stimulation techniques such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation. It will be argued that these data may be useful for advancing the concepts of pharmacotherapy and brain stimulation for recovery after stroke.

2. The blink reflex: Long known, but still fascinating

M. Kofler — 2012-03-01

The blink reflex is routinely used in clinical neurophysiology to characterize the functional integrity of the trigemino-facial reflex pathway covering supraorbital nerve, pons, medulla oblongata, and facial nerve. Recent findings of unconditioned blink reflex alterations, as well as changes in blink reflex modulation by subthreshold prepulse stimuli or suprathreshold double pulse stimulation, in patients with spinal cord injury or chronic pain syndromes, e.g. fibromyalgia, suggest plastic changes at the brainstem level in these conditions. The blink reflex and its modulation also serve to document acute pharmacological effects, e.g. following intrathecal bolus application of the GABA-ergic drug baclofen, thus concurring with an antispastic action of baclofen at the brainstem level. Finally, recent data suggest distinct influences of physiological variables, e.g. of age on blink reflex excitability recovery, and of gender on prepulse inhibition of the blink reflex. It remains to be elucidated whether the gender effect pertains to protective reflex mechanisms which are known to be more pronounced in females, or rather to neuropsychological mechanisms of gender-specific differences in filtering of afferent information flow through the brainstem, thereby influencing focused and diverted attention.

REM sleep and immunogenetic research in narcolepsy

S. Nevšímalová — 2012-03-01

The discovery of REM (Rapid Eye Movement) sleep laid the foundations for modern development of sleep medicine. Polysomnographic recording enabled to make distinction between different sleep stages, and on this basis, the criteria for different sleep disorders including narcolepsy came into being. The main feature of narcolepsy rests in increased REM sleep penetration verified by the multiple sleep latency test (MSLT). In clinical terms, the disease is marked by imperative attacks of daytime sleep and usually also by cataplexy – sudden loss of muscle tone evoked by emotive experience. The first indication of the immunogenetic basis of narcolepsy came with the discovery of its link to the HLA-DR2 (15) subgroup and with the subsequently revealed connection between narcolepsy–cataplexy and HLA-DQB1*0602.

4. Sleep apnoea syndrome in acute stroke patients – Results of the first phase prospective study

J. Slonková, M. Sedláková, Z. Soldánová, M. Kolibáčová, M. Štorkánová — 2012-03-01

Target: One-year follow-up of acute stroke patients with assessment of influence of obstructive sleep apnea (OSA) on final outcome after 3months and 1year after stroke. Methods: We present in 1st phase demographic data type of OSA, time onset and type of stroke of the 54 patients. Polygraphic finding is being performed up to 72h and 7days after stroke. Negative results of an apnea/hypopnea index (AHI) (up to AHI=4) form control group. We use basic statistic methods for quantitative and qualitative data, statistic hypothesis measured by parametric tests at 5% level of significance.

5. High prevalence of restless legs syndrome does not correlates with brain damage

J. Vavrova, J. Krasensky, K. Sonka, E. Havrdova, D. Kemlink — 2012-03-01

Introduction: Restless legs syndrome (RLS) has a prevalence of approx. 10% in the general population. Recently, multiple sclerosis (MS) was identified as a common cause for secondary RLS with prevalence ranging between 13.3% and 37.5%. The aim of our study was to evaluate the prevalence of RLS in MS and to compare the extent of brain damage between patients with and without RLS using magnetic resonance imaging (MRI).

6. Changes in strategy during the mental rotation task and its correlation with EEG

K. Štěpánová, M. Vavrečka, L. Lhotská — 2012-03-01

Shepard and Metzler (1971) showed that the mental rotation is performed with approximately steady rate. Further studies were concerned whether there is a relation between reaction times and stimuli complexity (both “piecemeal” theory and propositional theory predict decrease in the reaction times due to the increasing stimulus difficulty). Relation was not approved. Folk and Luce (1987) discuss possible problems in the methodology.

7. The inter-individual differences and the test–retest reliability of a EEG signal

M. Vavrečka, B. Rosset, L. Lhotská — 2012-03-01

The majority of EEG studies in the area of cognitive neuroscience are administered without any retest. The reliability of these studies should be questionable. The analysis of test–retest reliability in the Näpflin et al. study (2008) revealed high correlation between measurements. We did similar comparison and we also tested inter-individual differences and differences between scalp projections and source activity of independent components.

8. Sulcus temporalis superior

P. Haitová, R. Mareček, M. Mikl, M. Brázdil — 2012-03-01

Superior temporal sulcus (STS) is a brain structure, which has been related to many cognitive functions recently. It can be presumed that it is a part of many cognitive functions and that in particular situation, its relationship with other brain areas is relevant. Our work aimed to its effective connectivity during processing of potentially relevant unusual events.

9. Origins of VEP response suppression during prolonged visual motion stimulation

J. Kremláček, M. Kuba, Z. Kubová, J. Langrová, F. Vít, J. Szanyi — 2012-03-01

Response suppression of motion-onset visual evoked potentials (M-VEPs) can be measured during repetitive stimulation (Kremlacek et al. Doc Ophthalmol 115: 95–103; 2007). To reveal the origins of this suppression we evaluated the latency jittering and the effect of its correction on the amplitudes of dominant peaks P1, N2 and P3.

10. Electrophysiological correlate of auditory processing initiative on an unconscious level in the nucleus subthalamicus

E. Minks, P. Jurak, J. Halamek, J. Chladek, M. Bares — 2012-03-01

Introduction: In the protocol of mismatch negativity (MMN) the frequent and target auditory stimuli are presented to the patient while his attention is excluded. These evoked potentials (EP) are considered to correlate with automatic working memory and a primitive intelligence on an unconscious level. The aim of the study was to elucidate whether subthalamicus nucleus (STN) is involved in the processing of audio signals.

11. Pilot attempt to monitor Graves’ ophthalmopathy with pattern-reversal and motion-onset VEPS

J. Szanyi, J. Kremláček, Z. Kubová, J. Langrová, M. Kuba — 2012-03-01

Objective: The aim of this pilot study was to evaluate efficacy of visual evoked potentials (VEPs) in monitoring of visual functions during the high-dose intravenous steroid pulse therapy and apheresis treatment of severe Graves’ ophthalmopathy (GO).

12. Stance with head extension – Posturographic test

M. Kucharík, M. Šaling, J. Púčik — 2012-03-01

Stance with head extension represents significant stress on postural system. Posturographic studies on healthy young subjects indicate a reduction of stability during stance with head extension when compared to direct head position (Jaskson and Epstein, 1991). However, some patients with peripheral vestibular deficit improve postural stability during stance with head extension when comparing to stance with direct head position (Norris, 1995). Based on these data, we included stance with head extension to our posturographic examination. We compared measurements in stance with head extended (Ex) with parameters measured during the stance with direct head position (Pr). Both situations measured with eyes closed to eliminate the influence of visual information. For comparison of individual parameters of centre of pressure displacement, we used the formula (Ex−Pr/Ex+Pr)×100 (thus we get the differences between the measurements in percentages). During 3years 542 patients underwent our posturographic tests. We found that in healthy subjects head extension always led to deterioration of stability. Deterioration within 20% we considered as physiological variance. Higher values (20–25%) we observed in patients with cervical vertebral disabilities. Even higher values we observed in cerebellar patients or patients with atrophic brain process. Improvement of stability during stance with head extension was observed only in patients with peripheral vestibular impairment. According to our investigation we consider stance with head extension an appropriate test included in posturographic examination.

13. Cutaneous silent periods in multiple system atrophy

I. Štětkářová, M. Kofler — 2012-03-01

Objective: The cutaneous silent period (CSP) is a spinal inhibitory reflex mediated by A-delta fibers. Prolonged CSPs have previously been reported in patients with restless legs syndrome (RLS) and idiopathic Parkinson’s disease (IPD). Dopaminergic medication normalized the CSP alteration, concurring with dopaminergic influence on CSPs. To date, CSPs have not been extensively studied in patients with multiple system atrophy (MSA).

14. Electrophysiological intraoperative monitoring in vestibular schwannoma surgery

J. Ceé, T. Radovnický, R. Bartoš, P. Vachata, E. Provazníková, M. Sameš — 2012-03-01

We present the results of 48 patients, who underwent surgery of vestibular schwannomas (VS) from 2001 to 2011, with electrophysiological monitoring. Material and methods: Fifty operations (two re-resection). Monitoring used: EMG in identification and monitoring of CN VII, auditory evoked potentials (BAEP, ABR), motor evoked potentials (MEP). House–Brackmann scale (HB) was used in evaluation of postoperative deficit of CN VII. To determine the hearing disability we used audiometry or AAO-HNS score. We detected preoperative anacusis (respectively D score in the AAO-HNS classification) by 82% of patiens.

15. Intraoperative monitoring of evoked potentials in scoliosis surgery at University Hospital Brno

2012-03-01

Aim: The aim of our study was the evaluation of sensitivity and specificity of intraoperative monitoring (IOM) of evoked potentials (EP) in scoliosis and developmental spinal deformities surgery in our hospital.

16. Influence of water on the character of a surface EMG signal (WaS-EMG)

D. Pánek, D. Jurák, D. Pavlů, V. Krajča, J. Čemusová — 2012-03-01

Introduction: We present our personal experience with Water Surface Electromyography (WaS-EMG), and we compare our results with sources in the literature. Methodology: We started with a series of experiments conducted in the Swimming Sports Laboratory at FTVS, UK. We registered muscle activity with the help of a telemetric surface EMG instrument TelemyoMini 16 by Neurodata.

17. Oscillations in the basal ganglia – Cognitive aspects

M. Bočková, J. Chládek, P. Jurák, J. Halámek, M. Baláž, I. Rektor — 2012-03-01

Background: The aim of this work was to study high- frequency oscillations in the subthalamic nucleus and internal pallidum linked to cognitive and motor activities using event-related de/synchronizations (ERD/S) methodology.

18. Treatment-induced change of cortical activation: fMRI evidence of the central effect of BoNT-A

2012-03-01

The central mechanism of idiopathic dystonia is presumably localized within the brain although there has been no direct evidence for involvement of specific brain structures. Similarly, the exact cerebral correlate of post-stroke spasticity is unknown. We have performed a series of investigation with aiming to localize the potential central mechanisms.

19. Default mode network and extrastriate visual resting state network in patients with Parkinson’s disease dementia

I. Rektorova, L. Krajcovicova, R. Marecek, M. Mikl — 2012-03-01

Aims: Our aim was to evaluate two resting state networks (RSNs): the default mode network (DMN) and an extra-striate visual RSN (ESV-RSN) using the seed-based functional connectivity analysis of resting state data or deactivations in patients with Parkinson’s disease dementia (PDD) as compared with Parkinson’s disease (PD) without dementia and healthy controls (HC).

20. Neural correlates of traffic educational campaign content evaluation

J. Zelinková, R. Marecek, M. Mikl, T. Urbanek, L. Peterková, M. Brazdil — 2012-03-01

This study compare differences in brain activation during watching the video-clips from the national traffic educational campaign in contrast to neutral videos in order to identify which areas of the brain are involved in detailed perception of these videos and detection of differences between them. Functional magnetic resonance imaging data were acquired in 15 healths 19- to 28-year-old male volunteer drivers. During fMRI scanning, clips from the campaign with a catastrophic end were presented together with control videos without dramatic ending to participants. General linear model implemented in SPM5 software was used for analysis. Immediately after fMRI scanning, the verb description, valence and arousal (by scale from 1 to 10) were evaluated from participants. The maximum of significant difference in neuronal activity was observed within both-sided superior temporal sulci with only subtle left-sided predominance. These brain areas were activated more strongly during watching clips from the campaign in contrast to the control clips. The other, less extensive differences were observed mainly in left precuneus, right middle temporal gyrus and in left inferior parietal lobule. Activation in these brain regions did not show a significant correlation with subjective evaluation of valence and arousal for either category of videos. Involvement of these neural regions is often associated with perception of emotions and social cognition. Our results suggest that STS activation is related in our experiment with social perception more than with emotional processes.

21. Analysis of newborn EEG recorded at 40th week of postconceptional age

V. Gerla, V. Radisavljevic Djordjevic, L. Lhotska, V. Krajca, K. Paul — 2012-03-01

In this paper we present results of computer processing of newborn polysomnographic (PSG) recordings. For experiments we used data from 22 newborns, recorded at 40th week of postconceptional age, consisting of 8×EEG, EOG, EMG, ECG and PNG. For each recording, 6min of quiet sleep (QS) and active sleep (AS) were selected. These segments do not include physiological artifacts and can be regarded as representative for listed sleep stages. Data were collected, classified and selected by Karel Paul, MD.

22. Wavelet transform based features for analysis of newborn behavioral states

V. Radisavljevic Djordjevic, V. Gerla, R. Bělobrádek, L. Lhotská, V. Krajča — 2012-03-01

Computer-assisted processing of electroencephalographic (EEG) recordings permits computation and analyses of EEG features which were not possible only by visual analysis. In this study we addressed the application of the wavelet transform (WT) for analysis of newborn behavioral states. Selection of the most appropriate parameters of the transform was performed and potential of its features was tested.

23. Anti-CV2 associated cerebellar degeneration and polyneuropathy

2012-03-01

Introduction: Paraneoplastic damage of the nervous system frequently precedes the detection of the malignancy. Tumors cells indicate the production of anti-CV2 antibodies; that presence is associated with cerebellar degeneration, polyneuropathy and uveitis. The symptoms may occur acutely or subacutely.

24. Basal ganglia and cerebellum in the motor timing prediction task: Effective connectivity

I. Husárová, M. Mikl, O.V. Lungu, R. Mareček, J. Vaníček, M. Bareš — 2012-03-01

Objective: Over the years, the cerebellum, the basal ganglia (BG) and other cortical regions have emerged as important structures dealing with various aspects of timing. We investigated the effective connectivity (EC) and its modulation by behavioral outcome in a network comprised of cerebellum, BG and SMA in group of patients with Parkinson’s disease (PD) and healthy controls.

Clinical Neurophysiology

Contents

Editorial Board

Preliminary Announcement

Serendipity in nerve excitability research

The mismatch negativity (MMN) – A unique window to disturbed central auditory processing in ageing and different clinical conditions

The yield of routine electroencephalography in the detection of incidental nonconvulsive status epilepticus – A prospective study

Do sphenoidal electrodes aid in surgical decision making in drug resistant temporal lobe epilepsy?

Quantification and localization of EEG interictal spike activity in patients with surgically removed epileptogenic foci

Seizure clusters and adverse events during pre-surgical video-EEG monitoring with a slow anti-epileptic drug (AED) taper

Rhinal–hippocampal interactions during déjà vu

P300 in neglect

Finding the right control: The mismatch negativity under investigation

Foveal and parafoveal spatial attention and its impact on the processing of facial expression: An ERP study

Reorganization of multi-muscle and joint withdrawal reflex during arm movements in post-stroke hemiparetic patients

Short-latency crossed spinal responses are impaired differently in sub-acute and chronic stroke patients

Mu rhythm, visual processing and motor control

Limb segment vibration modulates spinal reflex excitability and muscle mRNA expression after spinal cord injury

Stretch reflex responses in Complex Regional Pain Syndrome-related dystonia are not characterized by hyperreflexia

The role of proprioception in the consolidation of ipsilateral 1Hz-rTMS effects on motor performance

Increased baseline temperature improves the acquisition of contact heat evoked potentials after spinal cord injury

Sex differences in auditory subcortical function

Evoked potentials and quantitative thermal testing in spinal cord injury patients with chronic neuropathic pain

Tonic pain and continuous EEG: Prediction of subjective pain perception by alpha-1 power during stimulation and at rest

Reference values for voluntary and stimulated single-fibre EMG using concentric needle electrodes: A multicentre prospective study

Quantification of motor unit action potential energy

Neuromuscular ultrasound in the diagnosis of focal neuropathies superimposed on polyneuropathy: A case report

Corrigendum to “Event-related brain potential modulation in patients with severe brain damage” [Clin. Neurophysiol. 122 (2011) 719–724]

1. Neuromodulation of motor learning in health and after stroke

2. The blink reflex: Long known, but still fascinating

REM sleep and immunogenetic research in narcolepsy

4. Sleep apnoea syndrome in acute stroke patients – Results of the first phase prospective study

5. High prevalence of restless legs syndrome does not correlates with brain damage

6. Changes in strategy during the mental rotation task and its correlation with EEG

7. The inter-individual differences and the test–retest reliability of a EEG signal

8. Sulcus temporalis superior

9. Origins of VEP response suppression during prolonged visual motion stimulation

10. Electrophysiological correlate of auditory processing initiative on an unconscious level in the nucleus subthalamicus

11. Pilot attempt to monitor Graves’ ophthalmopathy with pattern-reversal and motion-onset VEPS

12. Stance with head extension – Posturographic test

13. Cutaneous silent periods in multiple system atrophy

14. Electrophysiological intraoperative monitoring in vestibular schwannoma surgery

15. Intraoperative monitoring of evoked potentials in scoliosis surgery at University Hospital Brno

16. Influence of water on the character of a surface EMG signal (WaS-EMG)

17. Oscillations in the basal ganglia – Cognitive aspects

18. Treatment-induced change of cortical activation: fMRI evidence of the central effect of BoNT-A

19. Default mode network and extrastriate visual resting state network in patients with Parkinson’s disease dementia

20. Neural correlates of traffic educational campaign content evaluation

21. Analysis of newborn EEG recorded at 40th week of postconceptional age

22. Wavelet transform based features for analysis of newborn behavioral states

23. Anti-CV2 associated cerebellar degeneration and polyneuropathy

24. Basal ganglia and cerebellum in the motor timing prediction task: Effective connectivity