Cortical activation to voluntary movement in amyotrophic lateral sclerosis is related to corticospinal damage: electrophysiological evidence

ObjectivesThe time course of mu and beta sensorimotor rhythms, with event-related desynchronisation (ERD) to preparation and execution of voluntary movement followed by synchronisation (ERS) after movement, is considered to indicate cortical activation and idling, respectively. We investigated ERD and ERS in amyotrophic lateral sclerosis (ALS) patients and the relationship with anatomical and neurophysiological measures of corticospinal tract damage.MethodsPre-movement mu and beta ERD, and post-movement beta ERS were analysed in 16 ALS patients and 15 healthy controls performing self-paced brisk right thumb extensions. Apparent diffusion coefficient (ADC) of corticospinal tract was measured with magnetic resonance imaging (MRI). Motor-evoked potentials (MEPs) to the right abductor pollicis brevis were obtained using transcranial magnetic stimulation (TMS).ResultsMovement-related electromyographic activity was similar in the two groups. Post-movement ERS was significantly reduced in ALS group and negatively correlated with the amount of corticospinal damage as from MRI and TMS measures. ERD did not significantly differ between groups.ConclusionsAlterations of cortical activity in ALS patients were limited to the post-movement phase, as indicated by reduced ERS, and could be linked to reduced cortical inhibition rather than to generalised hyperexcitability.SignificanceThe correlation between ERS and corticospinal damage severity might be interpreted as a functional compensation or dysfunction of inhibitory systems paralleling corticospinal damage.     

Decreased movement-related beta desynchronization and impaired post-movement beta rebound in amyotrophic lateral sclerosis

ObjectiveThis study explored event-related desynchronization (ERD) and synchronization (ERS) in amyotrophic lateral sclerosis (ALS) to quantify cortical sensorimotor processes during volitional movements. We furthermore compared ERD/ERS measures with clinical scores and movement-related cortical potential (MRCP) amplitudes.MethodsElectroencephalograms were recorded while 21 ALS patients and 19 controls performed two self-paced motor tasks: sniffing and right index finger flexion. Based on Wavelet analysis the alpha and beta frequency bands were selected for subsequent evaluation.ResultsPatients generated significantly smaller resting alpha spectral power density (SPD) and smaller beta ERD compared to controls. Additionally patients exhibited merely unilateral post-movement ERS (beta rebound) whereas this phenomenon was bilateral in controls. ERD/ERS amplitudes did not correlate with corresponding MRCPs for either patients or controls.ConclusionsThe smaller resting alpha SPD and beta ERD and asymmetrical appearance of beta ERS in patients compared to controls could be the result of pyramidal cell degeneration and/or corpus callosum involvement in ALS.SignificanceThese results support the notion of reduced movement preparation in ALS involving also areas outside the motor cortex. Furthermore post-movement cortical inhibition seems to be impaired in ALS. ERD/ERS and MRCP are found to be independent measures of cortical motor functions in ALS.     

Cortical involvement in the sensory and motor symptoms of primary restless legs syndrome

BackgroundRestless legs syndrome (RLS) is characterized by closely interrelated motor and sensory disorders. Two types of involuntary movement can be observed: periodic leg movements during wakefulness (PLMW) and periodic leg movements during sleep (PLMS). Basal ganglia dysfunction in primary RLS has often been suggested. However, clinical observations raise the hypothesis of sensorimotor cortical involvement in RLS symptoms. Here, we explored cortical function via movement-related beta and mu rhythm reactivity.MethodsTwelve patients with idiopathic, primary RLS were investigated and compared with 10 healthy subjects. In the patient group, we analyzed event-related beta and mu (de)synchronization (ERD/S) for PLMS and PLMW during a suggested immobilization test (SIT). An ERD/S analysis was also performed in patients and controls during self-paced right ankle dorsal flexion at 8:30 PM (i.e., the symptomatic period for patients) and 8:30 AM (the asymptomatic period).ResultsBefore PLMS, there was no ERD. Intense ERS was recorded after PLMS. As with voluntary movement, cortical ERD was always observed before PLMW. After PLMW, ERS had a diffuse scalp distribution. Furthermore, the ERS and ERD amplitudes and durations for voluntary movement were greater during the symptomatic period than during the asymptomatic period and in comparison with healthy controls, who presented an evening decrease in these parameters. Patients and controls had similar ERD and ERS patterns in the morning.ConclusionOn the basis of a rhythm reactivity study, we conclude that the symptoms of RLS are related to cortical sensorimotor dysfunction.     

Altered pattern of motor cortical activation–inhibition during voluntary movements in Tourette syndrome

In patients with Gilles de la Tourette syndrome (GTS) alterations of motor cortex (M1) excitability at rest have been evidenced. In contrast, there has so far been little research into changes of motor cortical reactivity during the time course of voluntary movements in GTS patients. The present study investigates neuromagnetic event‐related desynchronization (ERD) and event‐related synchronization (ERS) of bilateral M1 in 11 GTS patients and 11 healthy control subjects. ERD represents motor cortical activation, whereas ERS most likely indicates its inhibition. Subjects performed a self‐paced finger movement task while magnetoencephalography was used to record neuromagnetic activity. In GTS patients, ERD at beta frequency was significantly increased in the contralateral hemisphere before and during movements, whereas ERS following movement termination was increased in M1 ipsilateral. Ipsilateral ERS was inversely correlated with tic severity as determined by the Yale Global Tic Severity Rating Scale. The data of the present study support the hypothesis that during voluntary movements, motor cortical reactivity is pathologically altered in GTS patients. The observed pattern of increased activation (ERD) prior to and during movement execution followed by increased inhibition (ERS) after movement termination at beta frequency suggests abnormally increased motor cortical activation, possibly driving stronger inhibition. The stronger this inhibition is, the better symptoms appear to be controlled. © 2010 Movement Disorder Society     

Event-related desynchronization and excitability of the ipsilateral motor cortex during simple self-paced finger movements.

OBJECTIVE: To study the time course of oscillatory EEG activity and corticospinal excitability of the ipsilateral primary motor cortex (iM1) during self-paced phasic extension movements of fingers II-V. METHODS: We designed an experiment in which cortical activation, measured by spectral-power analysis of 28-channel EEG, and cortical excitability, measured by transcranial magnetic stimulation (TMS), were assessed during phasic self-paced extensions of the right fingers II-V in 28 right-handed subjects. TMS was delivered to iM1 0-1500 ms after movement onset. RESULTS: Ipsilateral event-related desynchronization (ERD) during finger movement was paralleled by increased cortical excitability of iM1 from 0-200 ms after movement onset and by increased intracortical facilitation (ICF) without changes in intracortical inhibition (ICI) or peripheral measures (F waves). TMS during periods of post-movement event-related synchronization (ERS) revealed no significant changes in cortical excitability in iM1. CONCLUSIONS: Our findings indicate that motor cortical ERD ipsilateral to the movement is associated with increased corticospinal excitability, while ERS is coupled with its removal. These data are compatible with the concept that iM1 contributes actively to motor control. No evidence for inhibitory modulation of iM1 was detected in association with self-paced phasic finger movements. SIGNIFICANCE: Understanding the physiological role of iM1 in motor control.     

Event-related desynchronization and synchronization. Reactivity of electrocortical rhythms in relation to the planning and execution of voluntary movement]

Cortical electroencephalographic rhythms reactivity may be quantified using event-related desynchronization (ERD) and synchronization (ERS) methods. We therefore studied cortical activation occurring during programming and performance of voluntary movement in healthy subjects. EEG power evolution within the reactive frequency bands (mu and beta central rhythms) was averaged before, during and after a minimum of 50 self-paced flexions of the thumb. Recordings in 18 normal adults showed that ERD (decrease in power) of mu rhythm started 2,000 ms before movement onset, while ERD of beta rhythm started 1,500 ms before movement onset. Early ERD of mu and beta rhythms were located over the contralateral central region covering primary motor cortex. They were followed by bilateral ERD occurring over ipsilateral and contralateral central regions during performance of the movement. At the end of the movement, an ERS (increase in power) of beta rhythm occurred. These results suggest that programming of voluntary movement induces early activation in contralateral sensorimotor areas, while performance of the movement induces bilateral activation in sensorimotor areas. ERS of beta rhythm occurring at the end of the movement could correspond to inactivation of motor areas activated by movement. Based on EEG activity, ERD and ERS prove to be useful methods to analyze cortical activation during programming and performance of voluntary movements with good spatial and temporal resolution.     

Watching object related movements modulates mirror-like activity in parietal brain regions

ObjectiveWe studied the activation of cortical motor and parietal areas during the observation of object related grasping movements. By manipulating the type of an object (realistic versus abstract) and the type of grasping (correct versus incorrect), we addressed the question how observing such object related movements influences cortical rhythmicity, especially the mu-rhythm, in the context of an “extended” human mirror neuron system (MNS).MethodsMultichannel electroencephalogram (EEG) was recorded during the observation of different object-related grasping actions in twenty healthy subjects. Different movies were presented, showing sequences of correct or incorrect hand grasping actions related to an abstract or realistic (daily life) object.ResultsEvent-related de/synchronization (ERD/ERS) analyses revealed a larger ERD in the upper alpha (10–12 Hz), beta (16–20 Hz) and gamma (36–40 Hz) frequency bands over parietal brain regions depending on the type of grasping. The type of object only influenced ERD patterns in the gamma band range (36–40 Hz) at parietal sites suggesting a strong relation of gamma band activity and cortical object representation. Abstract and realistic objects produced lower beta band synchronization at central sites only, whereas depending on the type of grasping an ERS in the upper alpha band (10–12 Hz) was observed.ConclusionDepending on the type of the grasped object and the type of grasping stronger parietal cortical activation occurred during movement observation.SignificanceDiscussing the results in terms of an “extended” human mirror neuron system (MNS), it could be concluded that beside sensorimotor areas a stronger involvement of parietal brain regions was found depending on the type of object and grasping movement observed.     

Event-related synchronization (ERS): an electrophysiological correlate of cortical areas at rest.

Oscillations in the alpha and beta bands can display either an event-related blocking response or an event-related amplitude enhancement. The former is named event-related desynchronization (ERD) and the latter event-related synchronization (ERS). Examples of ERS are localized alpha enhancements in the awake state as well as sigma spindles in sleep and alpha or beta bursts in the comatose state. It was found that alpha band activity can be enhanced over the visual region during a motor task, or during a visual task over the sensorimotor region. This means ERD and ERS can be observed at nearly the same time; both form a spatiotemporal pattern, in which the localization of ERD characterizes cortical areas involved in task-relevant processing, and ERS marks cortical areas at rest or in an idling state.     

Event-related synchronization (ERS): an electrophysiological correlate of cortical areas at rest

Oscillations in the alpha and beta bands can display either an event-related blocking response or an event-related amplitude enhancement. The former is named event-related desynchronization (ERD) and the latter event-related synchronization (ERS). Examples of ERS are localized alpha enhancements in the awake state as well as sigma spindles in sleep and alpha or beta bursts in the comatose state. It was found that alpha band activity can be enhanced over the visual region during a motor task, or during a visual task over the sensorimotor region. This means ERD and ERS can be observed at nearly the same time; both form a spatiotemporal pattern, in which the localization of ERD characterizes cortical areas involved in task-relevant processing, and ERS marks cortical areas at rest or in an idling state.     

Structural and functional motor cortex asymmetry in unilateral lower limb amputation with phantom limb pain

ObjectiveThe role of motor cortex reorganization in the development and maintenance of phantom limb pain (PLP) is still unclear. This study aims to evaluate neurophysiological and structural motor cortex asymmetry in patients with PLP and its relationship with pain intensity.MethodsCross-sectional analysis of an ongoing randomized-controlled trial. We evaluated the motor cortex asymmetry through two techniques: i) changes in cortical excitability indexed by transcranial magnetic stimulation (motor evoked potential, paired-pulse paradigms and cortical mapping), and ii) voxel-wise grey matter asymmetry analysis by brain magnetic resonance imaging.ResultsWe included 62 unilateral traumatic lower limb amputees with a mean PLP of 5.9 (SD = 1.79). We found, in the affected hemisphere, an anterior shift of the hand area center of gravity (23 mm, 95% CI 6 to 38, p = 0.005) and a disorganized and widespread representation. Regarding voxel-wise grey matter asymmetry analysis, data from 21 participants show a loss of grey matter volume in the motor area of the affected hemisphere. This asymmetry seems negatively associated with time since amputation. For TMS data, only the ICF ratio is negatively correlated with PLP intensity (r = −0.25, p = 0.04).ConclusionThere is an asymmetrical reorganization of the motor cortex in patients with PLP, characterized by a disorganized, widespread, and shifted hand cortical representation and a loss in grey matter volume in the affected hemisphere. This reorganization seems to reduce across time since amputation. However, it is not associated with pain intensity.SignificanceThese findings are significant to understand the role of the motor cortex reorganization in patients with PLP, showing that the pain intensity may be related with other neurophysiological factors, not just cortical reorganization.     

Different patterns of movement-related cortical oscillations in patients with myoclonus and in patients with spinocerebellar ataxia

ObjectiveTo assess whether different patterns of EEG rhythms during a Go/No-go motor task characterize patients with cortical myoclonus (EPM1) or with spinocerebellar ataxia (SCA).MethodsWe analyzed event-related desynchronization (ERD) and synchronization (ERS) in the alpha and beta-bands during visually cued Go/No-go task in 22 patients (11 with EPM1, 11 with SCA) and 11 controls.ResultsIn the Go condition, the only significant difference was a reduced contralateral beta-ERS in the EPM1 patients compared with controls; in the No-go condition, the EPM1 patients showed prolonged alpha-ERD in comparison with both controls and SCA patients, and reduced or delayed alpha- and beta-ERS in comparison with controls. In both conditions, the SCA patients, unlike EPM1 patients and controls, showed minimal or absent lateralization of alpha- and beta-ERD.ConclusionsEPM1 patients showed abnormal ERD/ERS dynamics, whereas SCA patients mainly showed defective ERD lateralization.SignificanceA different behavior of ERS/ERD distinguished the two patient groups: the pattern observed in EPM1 suggests a prominent defect of inhibition occurring in motor cortex contralateral to activated segment, whereas the pattern observed in SCA suggested a defective lateralization attributable to the damage of cerebello-cortical network, which is instead marginal in patients with cortical myoclonus.     

Abnormal cortical mechanisms in voluntary muscle relaxation in de novo parkinsonian patients.

This study aimed at elucidating how the cortical mechanism underlying the preparation and the postmovement phase of voluntary hand muscle relaxation is affected in Parkinson's disease. Event-related mu and beta (de)synchronization (ERD/S) related to voluntary muscle contraction and relaxation were recorded in 16 untreated, akineto-rigid, predominantly hemiparkinsonian patients. The results were compared with data from 10 age-matched, healthy subjects. In the muscle relaxation task, the subject held the wrist in an extended position and then let the hand drop by voluntarily relaxing wrist extensor contraction, i.e., without any overt, associated muscle contraction. In the muscle contraction task, subjects performed a self-initiated brief wrist extension. A same pattern of ERD/S was observed in control subjects and parkinsonian patients performing the motor tasks with their less affected limb. In contrast, related to voluntary relaxation performed with the more affected limb, a delayed mu and beta ERD and a disappearance of beta ERS were revealed. These results demonstrate that the pattern of cortical oscillatory activity in a relaxation task is abnormal in parkinsonian patients. The authors suggest that this may be due to anomalous activity in inhibitory motor cortical systems and impaired sensorimotor integration of afferent inputs from muscle and joint receptors.     

Event-related beta EEG-changes during passive and attempted foot movements in paraplegic patients

A number of electroencephalographic (EEG) studies report on motor event-related desynchronization and synchronization (ERD/ERS) in the beta band, i.e. a decrease and increase of spectral amplitudes of central beta rhythms in the range from 13 to 35 Hz. Following an ERD that occurs shortly before and during the movement, bursts of beta oscillations (beta ERS) appear within a 1-s interval after movement offset. Such a post-movement beta ERS has been reported after voluntary hand movements, passive movements, movement imagination, and also after movements induced by functional electrical stimulation. The present study compares ERD/ERS patterns in paraplegic patients (suffering from a complete spinal cord injury) and healthy subjects during attempted (active) and passive foot movements. The aim of this work is to address the question, whether patients do have the same focal beta ERD/ERS pattern during attempted foot movement as healthy subjects do. The results showed midcentral-focused beta ERD/ERS patterns during passive, active, and imagined foot movements in healthy subjects. This is in contrast to a diffuse and broad distributed ERD/ERS pattern during attempted foot movements in patients. Only one patient showed a similar ERD/ERS pattern. Furthermore, no significant ERD/ERS patterns during passive foot movement in the group of the paraplegics could be found.     

Cortical network dysfunction revealed by magnetoencephalography in carriers of spinocerebellar ataxia 1 or 2 mutation

ObjectiveIn patients with spinocerebellar ataxia type 1 or 2 (SCA1 or SCA2) and in their asymptomatic gene-positive relatives (AsyRs) we investigated the event-related desynchronization and synchronisation (ERD/ERS) on magnetoencephalographic signals to assess the changes occurring before manifest ataxia, by comparing the results obtained in AsyRs and in their gene-negative healthy relatives (HRs).MethodsTwenty-four patients (12 SCA1, 12 SCA2), 24 AsyRs (13 SCA1, 11 SCA2) and 17 HRs performed a visually cued Go/No-go task. We evaluated the ERD/ERS in regions of interest corresponding to the frontal, central and parietal cortices.ResultsIn the SCA patients the main findings were a loss of side predominance for alpha and beta ERD and significantly weakened beta ERS. In AsyRs the main finding was a significantly enhanced alpha ERD, namely in those who were approaching the estimated time of symptom onset.ConclusionsIn ataxic patients, the loss of ERD lateralisation and the significantly reduction of beta ERS suggest defective bilateral processes that are involved in ending the movement. In AsyRs, enhanced alpha ERD proposes the presence of preclinical marker closely preceding symptom onset.SignificanceMovement-related ERD/ERS can detect the defective sensorimotor integration in ataxic patients, and reveals possible compensatory mechanisms in their AsyRs.     

Inter-hemispheric asymmetry of motor corticospinal excitability in major depression studied by transcranial magnetic stimulation

BACKGROUND: Imaging and electroencephalographic studies have reported inter-hemispheric asymmetries in frontal cortical regions associated with depression. This study aimed at comparing motor corticospinal excitability assessed by methods of transcranial magnetic stimulation (TMS) between the right and left hemispheres in patients with major depression and healthy controls. METHOD: Patients with major depression (n=35) and healthy controls (n=35) underwent a bilateral study of various motor corticospinal excitability parameters, including rest motor threshold (RMT), corticospinal silent period (CSP) duration and intra-cortical inhibition (ICI) and facilitation (ICF). Indexes of asymmetry were calculated, and the relationships between excitability parameters and clinical scores of depression were statistically analyzed. RESULTS: Depressed patients showed a reduced excitability of both excitatory (RMT, ICF) and inhibitory (CSP, ICI) processes in the left hemisphere, compared to the right hemisphere and to healthy controls. CONCLUSION: The present results confirmed the existence of inter-hemispheric asymmetries in frontal cortex activities of depressed patients in favor of a left-sided reduced excitability. This neurophysiological approach may help to guide repetitive TMS procedures in the treatment of depressive disorders.     

Evidence for cortical inhibitory and excitatory dysfunction in obsessive compulsive disorder

Several lines of evidence suggest that obsessive-compulsive disorder (OCD) is associated with an inability to inhibit unwanted intrusive thoughts. The neurophysiological mechanisms mediating such inhibitory deficits include abnormalities in cortical γ-aminobutyric acid (GABA) inhibitory as well as N-methyl-D-aspartate (NMDA) receptor-mediated mechanisms. Molecular evidence suggests that both these neurotransmitter systems are involved in OCD. Transcranial magnetic stimulation (TMS) represents a noninvasive technique to ascertain neurophysiological indices of inhibitory GABA and facilitatory NMDA receptor-mediated mechanisms. In this study, both mechanisms were indexed in 34 patients with OCD (23 unmedicated and 11 medicated) and compared with 34 healthy subjects. Cortical inhibitory and facilitatory neurotransmission was measured using TMS paradigms known as short-interval cortical inhibition (SICI), cortical silent period (CSP), and intracortical facilitation (ICF). Patients with OCD demonstrated significantly shortened CSP (p<0.001, Cohen's d=0.91) and increased ICF (p<0.009, Cohen's d=0.71) compared with healthy subjects. By contrast, there were no significant deficits in SICI. After excluding patients with OCD and comorbid major depressive disorder (MDD) from the analysis, these differences remained significant. Our findings suggest that OCD is associated with dysregulation in cortical inhibitory and facilitatory neurotransmission. Specifically, these findings suggest impairments in GABA(B) receptor-mediated and NMDA receptor-mediated neurotransmission. These findings are consistent with previously published genetic studies implicating GABA(B), and NMDA transporter and receptor genes in OCD. It is posited that dysregulation of such mechanisms may lead to the generation and persistence of intrusive thoughts that form the basis for this disorder.     

Prolonged cortical silent period is related to poor fitness and fatigue,but not tumor necrosis factor,in Multiple Sclerosis

ObjectivePoor fitness among people with Multiple Sclerosis (MS) aggravates disease symptoms. Whether low fitness levels accompany brain functioning changes is unknown.MethodsMS patients (n = 82) completed a graded maximal exercise test, blood was drawn, and transcranial magnetic stimulation determined resting and active motor thresholds, motor evoked potential latency, and cortical silent period (CSP).ResultsSixty-two percent of participants had fitness levels ranked below 10th percentile. Fitness was not associated with disability measured using the Expanded Disability Status Scale (EDSS). Regression analyses revealed that, cardiorespiratory fitness, when controlling for disease demographics, contributed 23.7% (p < 0.001) to the model explaining variance in CSP. Regression analysis using cardiorespiratory fitness and CSP as predictors showed that CSP alone explained 19.9% of variance in subjective fatigue (p = 0.002). Tumor necrosis factor was not associated with any variable.ConclusionLow fitness was associated with longer CSP in MS. Longer CSP was, in turn, related to greater MS fatigue.SignificanceMS patients had extremely low levels of cardiorespiratory fitness. Poor fitness predicted longer CSP, a marker of greater intracortical inhibition, which was linked to MS fatigue. Future research should examine whether aerobic training could shorten CSP and potentially lessen inhibition of cortical networks.     

Visuo‐attentional and sensorimotor alpha rhythms are related to visuo‐motor performance in athletes

This study tested the two following hypotheses: (i) compared with non‐athletes, elite athletes are characterized by a reduced cortical activation during the preparation of precise visuo‐motor performance; (ii) in elite athletes, an optimal visuo‐motor performance is related to a low cortical activation. To this aim, electroencephalographic (EEG; 56 channels; Be Plus EB‐Neuro) data were recorded in 18 right‐handed elite air pistol shooters and 10 right‐handed non‐athletes. All subjects performed 120 shots. The EEG data were spatially enhanced by surface Laplacian estimation. With reference to a baseline period, power decrease/increase of alpha rhythms during the preshot period indexed the cortical activation/deactivation (event‐related desynchronization/synchronization, ERD/ERS). Regarding the hypothesis (i), low‐ (about 8–10 Hz) and high‐frequency (about 10–12 Hz) alpha ERD was lower in amplitude in the elite athletes than in the non‐athletes over the whole scalp. Regarding the hypothesis (ii), the elite athletes showed high‐frequency alpha ERS (about 10–12 Hz) larger in amplitude for high score shots (50%) than for low score shots; this was true in right parietal and left central areas. A control analysis confirmed these results with another indicator of cortical activation (beta ERD, about 20 Hz). The control analysis also showed that the amplitude reduction of alpha ERD for the high compared with low score shots was not observed in the non‐athletes. The present findings globally suggest that in elite athletes (experts), visuo‐motor performance is related to a global decrease of cortical activity, as a possible index of spatially selective cortical processes (“neural efficiency”). Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

Selective and nonselective benzodiazepine agonists have different effects on motor cortex excitability

Transcranial magnetic stimulation (TMS) is a useful method to study pharmacological effects on motor cortex excitability. Zolpidem is a selective agonist of the benzodiazepine receptor subtype BZ1 and has a distinct pharmacological profile compared to diazepam. To study the different effects of these two drugs on the cortical inhibitory system, TMS was performed before and after administration of a single oral dose of zolpidem (10 mg) and diazepam (5 mg) in six healthy volunteers. TMS tests included the determination of resting and active motor threshold (MT) and measurements of the amplitudes of motor evoked potentials, intracortical facilitation (ICF), short-latency intracortical inhibition (SICI), and long-latency intracortical inhibition (LICI), and determination of the cortical silent period (CSP). Both drugs were without effect on the active or resting MT and decreased the ICF. Prolongation of the CSP and enhancement of LICI only in the presence of zolpidem point to a specific BZ1-related mechanism underlying the long-lasting component of cortical inhibition. This selective modulation of the CSP and the LICI points to a specific role of BZ1 receptors in the control of inhibitory neuronal loops within the primary motor cortex.     

Event-related EEG theta and alpha band oscillatory responses during language translation

Recent investigations on oscillatory EEG dynamics by means of event-related synchronisation and desynchronisation (ERS/ERD) suggest that first language semantic information processing is primarily reflected in the theta (4-7 Hz) and alpha (7-13 Hz) frequency bands. In this pilot study we explore whether similar ERS/ERD patterns emerge during language translation and which frequency bands sensitively respond to the difficulty of translation and the translation success. Thirteen female students of translation and interpreting were visually presented high and low frequency English words that had to be translated into German. Time-frequency representations of ERS/ERD between 2 and 50 Hz displayed a theta ERS response about 200-600 ms after word presentation, a beta ERD from about 400 ms, and alpha ERS and ERD patterns about 200-400 ms after word presentation. Statistical analyses of the ERS/ERD data in the theta (4-7 Hz), two alpha frequency bands (7-10 Hz and 10-13 Hz), and a beta band (20-30 Hz) predominantly revealed: (a) higher parietal theta ERS and frontal upper alpha ERD during the translation of low as compared to high frequency words, and (b) generally stronger ERD in the lower alpha band and larger left-hemispheric upper alpha ERD for successfully translated in contrast to not translated low frequency words. These findings provide first evidence of the sensitivity of the theta and alpha ERS/ERD measure to lexical-semantic processes involved in language translation.