Neurophysiological evidence of motor preparation in inner speech and the effect of content predictability.

Self-generated overt actions are preceded by a slow negativity as measured by electroencephalogram, which has been associated with motor preparation. Recent studies have shown that this neural activity is modulated by the predictability of action outcomes. It is unclear whether inner speech is also preceded by a motor-related negativity and influenced by the same factor. In three experiments, we compared the contingent negative variation elicited in a cue paradigm in an active vs. passive condition. In Experiment 1, participants produced an inner phoneme, at which an audible phoneme whose identity was unpredictable was concurrently presented. We found that while passive listening elicited a late contingent negative variation, inner speech production generated a more negative late contingent negative variation. In Experiment 2, the same pattern of results was found when participants were instead asked to overtly vocalize the phoneme. In Experiment 3, the identity of the audible phoneme was made predictable by establishing probabilistic expectations. We observed a smaller late contingent negative variation in the inner speech condition when the identity of the audible phoneme was predictable, but not in the passive condition. These findings suggest that inner speech is associated with motor preparatory activity that may also represent the predicted action-effects of covert actions.

Electrophysiological signatures of temporal context in the bisection task.

Despite having relatively accurate timing, subjective time can be influenced by various contexts, such as stimulus spacing and sample frequency. Several electroencephalographic (EEG) components have been associated with timing, including the contingent negative variation (CNV), offset P2, and late positive component of timing (LPCt). However, the specific role of these components in the contextual modulation of perceived time remains unclear. In this study, we conducted two temporal bisection experiments to investigate this issue. Participants had to judge whether a test duration was close to a short or long standard. Unbeknownst to them, we manipulated the stimulus spacing (Experiment 1) and sample frequency (Experiment 2) to create short and long contexts while maintaining consistent test ranges and standards across different sessions. The results revealed that the bisection threshold shifted towards the ensemble mean, and both CNV and LPCt were sensitive to context modulation. In the short context, the CNV exhibited an increased climbing rate compared to the long context, whereas the LPCt displayed reduced amplitude and latency. These findings suggest that the CNV represents an expectancy wave preceding a temporal decision process, while the LPCt reflects the decision-making process itself, with both components influenced by the temporal context.

Encoding, working memory, or decision: how feedback modulates time perception.

The hypothesis that individuals can accurately represent temporal information within approximately 3 s is the premise of several theoretical models and empirical studies in the field of temporal processing. The significance of accurately representing time within 3 s and the universality of the overestimation contrast dramatically. To clarify whether this overestimation arises from an inability to accurately represent time or a response bias, we systematically examined whether feedback reduces overestimation at the 3 temporal processing stages of timing (encoding), working memory, and decisions proposed by the scalar timing model. Participants reproduced the time interval between 2 circles with or without feedback, while the electroencephalogram (EEG) was synchronously recorded. Behavioral results showed that feedback shortened reproduced times and significantly minimized overestimation. EEG results showed that feedback significantly decreased the amplitude of contingent negative variation (CNV) in the decision stage but did not modulate the CNV amplitude in the encoding stage or the P2-P3b amplitudes in the working memory stage. These results suggest that overestimation arises from response bias when individuals convert an accurate representation of time into behavior. Our study provides electrophysiological evidence to support the conception that short intervals under approximately 3 s can be accurately represented as "temporal gestalt."

Electrophysiological correlates of response time outliers: Outlier related potentials.

In response time (RT) research, RTs which largely deviate from the RT distribution are considered "outliers". Outliers are typically excluded from RT analysis building upon the implicit assumption that cognitive processing is distorted in outlier trials. The present study aims to test this assumption by comparing cognitive processing indexed by event-related potentials (ERP) of trials with outliers and valid trials in two different tasks. To this end, we compared stimulus- and response-locked ERPs for outliers identified by nine different methods with valid trials, using cluster-based permutation tests. Consistently across outlier exclusion methods and tasks, the late positive complex (P3) associated with response-related processes was reduced in outliers. Analyses of response-locked ERPs related this P3 attenuation to a slower and temporally more extended increase of the P3, possibly indexing reduced evidence accumulation speed in outliers. P3 peak amplitude in response-locked ERPs was similar between outliers and valid trials, suggesting that the absolute amount of evidence required for a response remained comparable. Furthermore, in addition to these more general ERP correlates of outliers, the contingent negative variation (CNV) ERP component was reduced in outliers as a function of preparatory demands of the task. Hence, electrophysiological correlates, and thus cognitive processing, are altered in outliers compared to valid trials. In order to avoid distortion of observed ERP differences between conditions, the RT outlier distribution should be considered for the analysis of ERPs in combined ERP and RT studies.

Neuroelectric indices of motor response preparation are selectively associated with physical activity among adults with obesity.

Previous work has demonstrated that physical activity and weight status are associated with attentional inhibition (indexed with the P3 component of event-related potentials). However, there is limited knowledge on the neural underpinnings of motor response planning and activation. This study investigated the effect of weight status on relationships between moderate-to-vigorous physical activity (MVPA) and the lateralized readiness potential (LRP), a neuroelectric index of motor response planning and activation. Adults (N = 165 [98 females]) wore ActiGraph wGT3X+ accelerometers to measure physical activity. Behavioral outcomes were recorded during the modified Eriksen Flanker task to assess attentional inhibition. EEG recordings were taken to elucidate response- (LRP-R) and stimulus-locked (LRP-S) LRPs, and P3. Participants were separated into groups based on the BMI cutoff of 30 kg/m2 (i.e., non-obese [n = 88], obese [n = 77]). Independent t-tests and ANCOVA were conducted to determine differences between groups. Regression analyses within each group were conducted to determine relationships between MVPA and LRP and P3 amplitude and latencies. There was no difference in MVPA between weight groups after adjustment for age and sex, although the non-obese group had significantly higher incongruent accuracy (p = 0.007). Only in the obese group, MVPA was positively associated with LRP-R incongruent (ß = 0.014, p = 0.029) and LRP-S congruent (ß = 0.013, p = 0.008) amplitude, and inversely associated with LRP-S incongruent (ß = -0.488, p = 0.017) and P3 congruent (ß = 0.013, p = 0.008) fractional area latency. MVPA was associated with pre-motor planning and activation only among persons with obesity. Future work should study the impact of physical activity on neuroelectric indices of motor responses in people with obesity.

The Dominance of Anticipatory Prefrontal Activity in Uncued Sensory-Motor Tasks.

Anticipatory event-related potentials (ERPs) precede upcoming events such as stimuli or actions. These ERPs are usually obtained in cued sensory-motor tasks employing a warning stimulus that precedes a probe stimulus as in the contingent negative variation (CNV) paradigms. The CNV wave has been widely studied, from clinical to brain-computer interface (BCI) applications, and has been shown to emerge in medial frontoparietal areas, localized in the cingulate and supplementary motor areas. Several dated studies also suggest the existence of a prefrontal CNV, although this component was not confirmed by later studies due to the contamination of ocular artifacts. Another lesser-known anticipatory ERP is the prefrontal negativity (pN) that precedes the uncued probe stimuli in discriminative response tasks and has been localized in the inferior frontal gyrus. This study aimed to characterize the pN by comparing it with the CNV in cued and uncued tasks and test if the pN could be associated with event preparation, temporal preparation, or both. To achieve these aims, high-density electroencephalographic recording and advanced ERP analysis controlling for ocular activity were obtained in 25 volunteers who performed 4 different visuomotor tasks. Our results showed that the pN amplitude was largest in the condition requiring both time and event preparation, medium in the condition requiring event preparation only, and smallest in the condition requiring temporal preparation only. We concluded that the prefrontal CNV could be associated with the pN, and this activity emerges in complex tasks requiring the anticipation of both the category and timing of the upcoming stimulus. The proposed method can be useful in BCI studies investigating the endogenous neural signatures triggered by different sensorimotor paradigms.

Face specific neural anticipatory activity in infants 4 and 9 months old.

The possibility of predicting the specific features of forthcoming environmental events is fundamental for our survival since it allows us to proactively regulate our behaviour, enhancing our chance of survival. This is particularly crucial for stimuli providing socially relevant information for communication and interaction, such as faces. While it has been consistently demonstrated that the human brain shows preferential and ontogenetically early face-evoked activity, it is unknown whether specialized neural routes are engaged by face-predictive activity early in life. In this study, we recorded high-density electrophysiological (ERP) activity in adults and 9- and 4-month-old infants undergoing an audio-visual paradigm purposely designed to predict the appearance of faces or objects starting from congruent auditory cues (i.e., human voice vs nonhuman sounds). Contingent negative variation or CNV was measured to investigate anticipatory activity as a reliable marker of stimulus expectancy even in the absence of explicit motor demand. The results suggest that CNV can also be reliably elicited in the youngest group of 4-month-old infants, providing further evidence that expectation-related anticipatory activity is an intrinsic, early property of the human cortex. Crucially, the findings also indicate that the predictive information provided by the cue (i.e., human voice vs nonhuman sounds) turns into the recruitment of different anticipatory neural dynamics for faces and objects.

Reduced neural activity when anticipating social versus nonsocial rewards in schizophrenia: Preliminary evidence from an ERP study.

Diminished social motivation is a core feature of schizophrenia that might reflect disturbances in social reward processing. It is not known whether these disturbances reflect anticipatory ("wanting") and/or consummatory ("liking") pleasure deficits. The primary aim of this study was to examine social versus nonsocial reward processing during these temporally distinct substages using event-related potential (ERP) components. Twenty-three schizophrenia participants and 20 healthy participants completed an incentive delay task with social (i.e., smiling expressions) and nonsocial (i.e., money) rewards. We measured two anticipatory ERPs (i.e., "wanting") (target anticipation: Contingent Negative Variation [CNV]; feedback anticipation: Stimulus Preceding Negativity [SPN]) and one consummatory ERP (i.e., "liking") (feedback receipt: P300). As a secondary aim, we examined correlations between the ERPs and interview-rated motivational negative symptoms and social functioning. Schizophrenia participants showed overall less target anticipation (blunted CNV) across all trials (social and nonsocial) than healthy participants. Importantly, schizophrenia participants exhibited less anticipation of social rewards relative to nonsocial rewards (SPN), whereas healthy participants showed similar anticipation for both reward types. Both groups showed similar responses to social and nonsocial reward receipt (P300). Furthermore, social reward anticipation during the incentive delay task was associated with more social approach behaviors in the real-world. Together, these findings provide preliminary evidence for intact social reward "liking" and impaired "wanting" in schizophrenia.

Neural mechanisms of motor dysfunction in individuals at clinical high-risk for psychosis: Evidence for impairments in motor activation.

Motor abnormalities are a core feature of psychotic disorders observed from the premorbid period through chronic illness, suggesting motor dysfunction may reflect the pathophysiology of psychosis. Electrophysiology research in schizophrenia suggests impaired motor activation and preparation may underlie these motor abnormalities. Despite behavioral studies suggesting similar motor dysfunction in those at clinical high-risk (CHR) for psychosis, there have been no studies examining neural mechanisms of motor dysfunction in the CHR period, where research can inform pathophysiological and risk models. The present study used the lateralized readiness potential (LRP), an event-related potential index of motor activation and preparation, to examine mechanisms of motor dysfunction in 42 CHR and 41 control participants (N = 83, 56% female). Response competition was manipulated to determine whether deficits are secondary to cognitive control impairments or reflect primary motor deficits. Behaviorally, CHR participants exhibited overall slower responses than controls. Further, relative to controls, CHR participants showed reduced activation of correct but not incorrect responses, reflected in blunted LRP amplitude under weak response competition and no difference in amplitude associated with the incorrect response under strong response competition. This pattern of results suggests individuals at CHR for psychosis exhibit primary motor deficits in activating and preparing behavioral responses and are contrary to a deficit in cognitive control. Further, blunted LRP amplitude was associated with worsening of negative symptoms at 12-month follow-up. Together, these findings are consistent with LRP studies in psychosis and implicate motor activation deficits as potential mechanisms of motor dysfunction in the high-risk period. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Motor preparation impairment in multiple sclerosis: Evidence from the Bereitschaftspotential in simple and complex motor tasks.

OBJECTIVES: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system, characterized by the accumulation of demyelinating lesions and axonal loss over its course. This study aimed to increase current knowledge of motor preparation in this condition, by assessing the two components of the Bereitschaftspotential (BP1 and BP2), also known as the readiness potential. METHODS: Twelve patients with MS and ten age- and gender-matched healthy controls (HC) were included. Patients' demographic and clinical data were collected. Participants were asked to perform two different tasks, a simple index extension and a Luria sequence. BP1 and BP2 values were obtained from 18 central electroencephalography electrodes and were compared between the two groups. RESULTS: Compared to HC, patients with MS showed earlier BP1 onset (i.e., longer latency) in almost all the analyzed scalp regions during index extension. This was also observed during the Luria sequence, but only in the centro-parietal regions. As for BP2 latency, no significant difference was noted between groups during either task. With regard to amplitudes, patients with MS had larger BP1 amplitudes in the right fronto-central area during index extension and greater BP1 and BP2 amplitudes in bilateral centro-parietal and left central regions during the Luria task. BP1 latency was also found to be significantly correlated with disease duration and performance on executive function tests (Trail Making Test). CONCLUSIONS: This study showed, for the first time, changes in the Bereitschaftspotential in patients with MS. These data reflect prolonged movement preparation in this population and may suggest global alteration of the premotor scheme.

Exploration of cortical inhibition and habituation in insomnia: Based on CNV and EEG.

OBJECTIVE: Cognitive dysfunction with abnormal cortical inhibition and habituation has frequently been found in patients with insomnia. And the so-called contingent negative variation (CNV) and EEG power spectral density (FFT) may be the best choice to explore the underlining pathophysiology. METHODS: We used polysomnography (PSG) to record such objective PSG parameters. The amplitudes, latencies, areas of different CNV components such as oCNV, iCNV and tCNV, PINV have been selected and analyzed. Behavioral data such as manual reaction time (RT) has been analyzed. Spectral analysis was performed with fast Fourier transformation (FFT) on all channels to make a spectral analyses of EEG datas. RESULTS: The A-latency located in CZ or PZ were statistically longer in insomnia group than control group, the iCNV-latency located in insomnia group were statistically shorter than control group. The iCNV-amplitude located in insomnia group was lower than control group. The oCNV-amplitude or the tCNV-amplitude located in insomnia group was higher than control group. The oCNV-square, tCNV-square, or PINV-square located in insomnia group were significant larger than control group. ß1 or ß2 activity distributed in bilateral hemisphere were significantly increased in insomnia group than control group with different distributions. DISCUSSION: Our study revealed varied attentional and information processing in insomnia patients. Above all, we made a hypothesis with ceiling theory: Frontal lobe play an important role in maintaining cognitive processing, which needs much more energy consumption and leads to decreased fast EEG activity in frontal cortex, which contributes to reduced cortical inhibition, represented as abnormal CNV.

Electrophysiological evidence against parallel motor processing during multitasking.

We combined behavioral measures with electrophysiological measures of motor activation (i.e., lateralized readiness potentials, LRPs) to disentangle the relative contribution of premotor and motor processes to multitasking interference in the prioritized processing paradigm. Specifically, we presented stimuli of two tasks (primary and background task) in each trial, but participants were instructed to perform the background task only if the primary task required no response. As expected, task performance was substantially influenced by a task probability manipulation: Background task responses were faster, psychological refractory period effects were smaller, and interference from the second task (i.e., backward compatibility effects) was larger when there was a larger probability that this task required a response. Critically, stimulus-locked and response-locked LRP analyses indicate that these behavioral effects of parallel processing were not driven by background task motor processing (e.g., motoric response activation) taking place during primary task processing. Instead, the LRP results suggest that these effects were exclusively localized during premotor stages of processing (e.g., response selection). Thus, the present results generally provide evidence for multitasking accounts allowing parallel task processing during response selection, whereas the task-specific motor responses are activated in a serial manner. One plausible account is that multiple task information sources can be processed in parallel, with sharing of limited cognitive resources depending on task relevance, but a primary and still active task goal prevents motor activation related to the goals of other tasks in order to avoid outcome conflict.

Dealing with uncertainty: A high-density EEG investigation on how intolerance of uncertainty affects emotional predictions.

Intolerance of uncertainty (IU) can influence emotional predictions, constructed by the brain (generation stage) to prearrange action (implementation stage), and update internal models according to incoming stimuli (updating stage). However, neurocomputational mechanisms by which IU affects emotional predictions are unclear. This high-density EEG study investigated if IU predicted event-related potentials (ERPs) and brain sources activity developing along the stages of emotional predictions, as a function of contextual uncertainty. Thirty-six undergraduates underwent a S1-S2 paradigm, with emotional faces and pictures as S1s and S2s, respectively. Contextual uncertainty was manipulated across three blocks, each with 100%, 75%, or 50% S1-S2 emotional congruency. ERPs, brain sources and their relationship with IU scores were analyzed for each stage. IU did not affect prediction generation. During prediction implementation, higher IU predicted larger Contingent Negative Variation in the 75% block, and lower left anterior cingulate cortex and supplementary motor area activations. During prediction updating, as IU increased P2 to positive S2s decreased, along with P2 and Late Positive Potential in the 75% block, and right orbito-frontal cortex activity to emotional S2s. IU was therefore associated with altered uncertainty assessment and heightened attention deployment during implementation, and to uncertainty avoidance, reduced attention to safety cues and disrupted access to emotion regulation strategies during prediction updating.

Approach of visual stimuli facilitates the prediction of tactile events and suppresses beta band oscillations around the primary somatosensory area.

The purpose of the present study was to investigate whether the approach of visual stimuli influences prediction of subsequent tactile events. For this purpose, we examined electroencephalograms (EEGs) during the prediction of tactile events when visual stimuli did or did not approach. Tactile stimuli were presented with a high probability (80%) of being applied to the left (or right) index finger and a low probability (20%) of being applied to the opposite index finger. In the approach condition, visual stimuli were presented towards the hand to which the high-probability tactile stimuli were presented; in the neutral condition, visual stimuli did not approach. The result of time-frequency analysis for the EEGs showed that beta band event-related spectral perturbation at the electrodes around the primary somatosensory area (C3 and C4) was suppressed about 300 ms before the presentation of a tactile stimulus and that event-related desynchronization (ERD) occurred in all conditions. Moreover, the beta band ERD of the approach condition was larger than that of the neutral condition. These results provide evidence that the approach of visual stimuli facilitates prediction itself for subsequent tactile events.

Electrophysiological correlates of the somatotopically organized tactile duration aftereffect.

Adaptation to sensory events of long or short duration leads to a negative aftereffect, in which a new target event (of median duration) following the adaptation will be perceived to be shorter or longer than is actually the case. This illusion has been observed in visual, auditory, and tactile modalities. This study used event-related potentials (ERPs) to examine the tactile duration aftereffect, using the contingent negative variation (CNV) and the late positive component (LPC) as a way to characterize the temporal processes. The tactile duration adaptation was found to induce a significant aftereffect within a somatotopic framework. Moreover, the CNV in the contralateral scalp and the LPC in the fronto-central scalp were both modulated by the tactile duration adaptation. Specifically, adaptation to a short tactile duration increased the CNV and LPC amplitudes, whereas adaptation to a long tactile duration decreased them. This modulation was contingent on the topographic distance between fingers, which was only observed when the adapting and test fingers were consistent or adjacent, but not homologous. In sum, these results reveal a coherent behavioral-electrophysiological link in the somatotopically organized tactile duration aftereffect.

Effects of rhythmic visual cues on cognitive resources allocation characterized by electroencephalographic (EEG) features during human gait initiation.

Rhythmic visual cues are beneficial in gait initiation (GI) in Parkinson's disease patients with freezing of gait (FOG), however, the underlying neurophysiological mechanism remains poorly understood. The cognitive control modulated by visual cues during GI has been investigated and considered as a potential factor influencing automatic motor actions, but it is unclear how rhythmic visual cues affect cognitive resources demands during GI. The purpose of this study was to explore the effect of rhythmic visual cues on cognitive resources allocation by recording the anticipatory cerebral cortex electroencephalographic (EEG) activity during GI. Twenty healthy participants initiated gait in response to the rhythmic and non-rhythmic visual cues of stimulus presentation. We assessed the contingent negative variation (CNV) of averaged EEG data over 32 electrode positions during GI preparation, the results of which showed that the CNV was induced over prefrontal, frontal, central, and parietal regions in both rhythmic conditions and non-rhythmic conditions. Overall, different visual cues modulated the amplitude of CNV in the early and late stages of the GI preparation. Compared with the non-rhythmic condition, the CNV amplitude was lower in rhythmic condition over displayed regions precede the GI onset. In the late stage of GI preparation, it showed significant differences between the two conditions in prefrontal, frontal, and central regions, and the amplitude of CNV was lower under rhythmic condition. More to the point, the differences were more obvious in the late stage of GI preparation between the two conditions, which was closely associated with the cognitive resources. Therefore, the results indicate that less cognitive resources allocation is required to trigger GI under rhythmic visual cues compared with non-rhythmic visual cues. This study may provide a new insight into why rhythmic visual cues are more effective in improving GI ability compared to non-rhythmic visual cues.

Sensory tricks in cervical dystonia correlate with enhanced brain activity during motor preparation.

INTRODUCTION: Although sensory tricks are well known as the maneuvers that temporarily relieve dystonic symptoms in patients with cervical dystonia (CD), the underlying neurophysiological mechanisms remain unclear. We aimed to investigate brain potentials related to sensory tricks in patients with CD. METHODS: Thirteen patients with CD and 13 age-matched healthy volunteers participated. The experiment consisted of three conditions (moving the neck, moving an arm, and performing sensory tricks) presented in different blocks in random order in a contingent negative variation (CNV) paradigm. Warning and trigger stimuli (S1 and S2) were presented to the participants, who were instructed to prepare to perform the specific task for each condition after S1, and then to perform the task after S2. Early and late components of the CNV were measured. RESULTS: The late CNVs in patients with CD were significantly larger than those in healthy participants in Fz, FCz, Cz, and C3 electrodes. Only in patients with CD, the late CNVs were significantly greater for the 'sensory tricks' condition compared to the 'move neck' condition in Fz and C3 electrodes. CONCLUSION: The late CNV is increased during sensory tricks in patients with CD, suggesting that sensory tricks may affect mechanisms related to the motor preparatory phase in the premotor and primary motor areas. Sensory tricks may normalize impaired motor preparation in dystonia, leading to improved dystonic symptoms.

Hidden wounds of violence: Abnormal motor oscillatory brain activity is related to posttraumatic stress symptoms.

Victims of urban violence are at risk of developing Posttraumatic Stress Disorder (PTSD), one of the most debilitating consequences of violence. Considering that PTSD may be associated with inefficient selection of defensive responses, it is important to understand the relation between motor processing and PTSD. The present study aims to investigate the extent to which the severity of posttraumatic stress symptoms (PTSS) is related to motor preparation against visual threat cues in victims of urban violence. Participants performed a choice reaction time task while ignoring a picture that could be threating or neutral. The EEG indices extracted were the motor-related amplitude asymmetry (MRAA) in the alpha frequency range, and the lateralized readiness potential (LRP). We observed a linear relation between longer LRP latency and a slower reaction time, selectively during threat processing (compared to neutral) in low PTSS, but not in high PTSS participants. Alpha MRAA suppression and the PTSS were also linearly related: the smaller the alpha MRAA suppression in the threat condition relative to neutral, the greater the PTSS. These results provide evidence that threatening cues affect motor processing that is modulated by the severity of PTSS in victims of urban violence.

Neurophysiological mechanisms underlying motor feature binding processes and representations.

Coherent, voluntary action requires an integrated representation of these actions and their defining features. Although theories delineate how action integration requiring binding between different action features may be accomplished, the underlying neurophysiological mechanisms are largely elusive. The present study examined the neurophysiological mechanisms underlying binding processes in actions. To this end, we conducted EEG recordings and applied standard event-related potential analyses, temporal EEG signal decomposition and multivariate pattern analyses (MVPA). According to the code occupation account, an overlap between a planned and a to-be-performed action impairs performance. The level, to which performance is attenuated depends on the strength of binding of action features. This binding process then determines the representation of them, the so-called action files. We show that code occupation and bindings between action features specifically modulate processes preceding motor execution as showed by the stimulus-locked lateralized readiness potential (LRP). Conversely, motor execution processes reflected by the response-locked LRP were not modulated by action file binding. The temporal decomposition of the EEG signal, further distinguished between action file related processes: the planned response determining code occupation was reflected in general (voluntary) response selection but not in involuntary (response priming-related) activation. Moreover, MVPA on temporally decomposed neural signals indicated that action files are represented as a continuous chain of activations. Within this chain, inhibitory and response re-activation patterns can be distinguished. Taken together, the neurophysiological correlates of action file binding suggest that parallel, stimulus- and response-related pre-motor processes are responsible for the code occupation in the human motor system.

Lateralized readiness potentials and sensorimotor activity in adults with obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) patients are known to have various functional abnormalities in prefrontal and motor areas. Given the presence of compulsions in many OCD patients, impaired response preparation processes could be a core feature of OCD. Yet, these processes remain understudied from a neurophysiological standpoint. Nineteen OCD patients were matched on age and sex to 19 healthy controls. Continuous EEG was recorded in all participants during a stimulus-response compatibility task. EEG from electrodes C3 and C4 was then averaged into stimulus- and response-locked LRPs. We compared both groups on various LRP measures, such as the LRP onset, the Gratton dip, and the maximum LRP peak. OCD patients showed significantly larger LRP peak than healthy controls, as well as larger Gratton dip. However, there was no group difference regarding LRP onset. Among OCD patients, it seems that motor regions are overactive during response preparation. Such overactivity was found for both incorrect responses that are aborted before execution and responses that are truly executed. These results suggest that regulation of sensorimotor activity should be addressed in the treatment of OCD.