Contingent negative variation in epilepsy

The contingent negative variation (CNV) is a long-latency event-related potential elicited by paired or associated stimuli. We recorded contingent negative variation in 50 patients with complex partial and secondarily generalized seizures and in 20 neurologically and psychiatrically normal unmedicated controls.CNV was recorded from Fz, Cz, and Pz. A 2000 Hz tone was followed after 1.5 s by 1000 microsecond light flash, at which a button press was to be executed. Filter band pass was 0.1–20 Hz, analysis time was 10s and 10 responses were replicated.Patients with complex partial seizures with and without secondary generalization had lower measurements of area under the CNV curve (AUC) than did controls, and CNV amplitude was significantly reduced. Patients with interictal behavioural symptoms had significantly smaller AUC and lower amplitude. No significant difference was found between depressed and non-depressed seizure patients with respect to AUC, but amplitude was significantly lower in depressed patients. Seizure patients with psychosis had significantly lower AUC but did not differ from non-psychotic patients in CNV amplitude. No differences were found between seizure patients with and without personality disorder with respect to CNV AUC or amplitude. Post-imperative negative variation was significantly more common in seizure patients than in controls and among patients with epilepsy, was significantly increased in those with inter-ictal behaviour disturbance generally and psychosis particularly. No specific effect of anticonvulsant monotherapy on AUC or amplitude was identified.These findings suggest that CNV may differ between partial epilepsy patients and controls, and that inter-ictal behaviour disturbance may particularly affect CNV measures. They also agree with previous evidence for a frontal lobe generator for the CNV, and a possible role for central dopaminergic pathways in the production of PINV

Contingent Negative Variation: Sensitivity to Directed Attention

The exact nature of the contingent negative variation (CNV) event-related potential (ERP) remains unclear after decades of research. Although this ERP has long been associated with anticipation of motor responses, it remains present in the absence of physical action. Attention and arousal may better account for production of this ERP. In the current study, we examined the role directed attention may play in CNV production, while controlling for the expectancy of stimulus presentation based on the mean probability of stimulus duration. We hypothesized that if direction of attention, rather than probability of stimulus presentation, had the most pronounced effect, differences in slope and mean amplitude during different measurement windows would be seen, based on the length of different auditory stimuli. CNV slope was found to differ as a function of attention allocation. The potential role attention plays on CNV production as it relates to complex, time-based decisional-making processes is discussed

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 inf luenced 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

The Contingent Negative Variation: The Cumulative Curve Method Revisited

The contingent negative variation (CNV) slow waves were elicited using a modified version of the standard paradigm matching the earlier work of Timsit-Berthier. Three parameters, the A3, A5 and post-imperative negative variation (PINV), are measured on four blocks of three to five trials and plotted into a cumulative curve. Five different types of cumulative curves are identified and used for further analysis of a clinical population. A literature review, applying the four-step approach for developing diagnostic tests in psychiatry by Boutros and colleagues is used to assess the current state of CNV as a clinical tool. Two clinical examples are used to illustrate that the cumulative curve reflects the current state of a mental disorder and that follow-up reflects the (un)favorable evolution. Clinical observations indicate that when taking into account the state of a mental disorder, the CNV has potential as a diagnostic aid and can play an active role in the therapeutic decision process

Contingent negative variation (CNV) associated with sensorimotor timing error correction.

INTRODUCTION: Detection and subsequent correction of sensorimotor timing errors are fundamental to adaptive behavior. Using scalp-recorded event-related potentials (ERPs), we sought to find ERP components that are predictive of error correction performance during rhythmic movements. METHOD: Healthy right-handed participants were asked to synchronize their finger taps to a regular tone sequence (every 600ms), while EEG data were continuously recorded. Data from 15 participants were analyzed. Occasional irregularities were built into stimulus presentation timing: 90ms before (advances: negative shift) or after (delays: positive shift) the expected time point. A tapping condition alternated with a listening condition in which identical stimulus sequence was presented but participants did not tap. RESULTS: Behavioral error correction was observed immediately following a shift, with a degree of over-correction with positive shifts. Our stimulus-locked ERP data analysis revealed, 1) increased auditory N1 amplitude for the positive shift condition and decreased auditory N1 modulation for the negative shift condition; and 2) a second enhanced negativity (N2) in the tapping positive condition, compared with the tapping negative condition. In response-locked epochs, we observed a CNV (contingent negative variation)-like negativity with earlier latency in the tapping negative condition compared with the tapping positive condition. This CNV-like negativity peaked at around the onset of subsequent tapping, with the earlier the peak, the better the error correction performance with the negative shifts while the later the peak, the better the error correction performance with the positive shifts. DISCUSSION: This study showed that the CNV-like negativity was associated with the error correction performance during our sensorimotor synchronization study. Auditory N1 and N2 were differentially involved in negative vs. positive error correction. However, we did not find evidence for their involvement in behavioral error correction. Overall, our study provides the basis from which further research on the role of the CNV in perceptual and motor timing can be developed

An Investigation of the Contingent Negative Variation Using Signal Processing Methods

The Contingent Negative Variation (CNV) is one of many types of electrical response signals which appear in the electroencephalogram (EEG) of man subsequent to one or more stimuli. Generally these responses are small in comparison to the normal background EEG and had always been thought to consist of a response component which was added to the background EEG. Professor B. McA. Sayers of Imperial College suggested that the auditory response might actually be due to a temporary ordering of the phases of the components of the background EEG. A model, allowing for additive and ordering effects, is proposed here. This model was tested on both auditory and CNV responses using statistical tests not previously used in evoked potential studies. The tests showed that while the additive model satisfactorily described the auditory responses, it did not explain the CNV responses so well. However, both sets of responses showed a certain amount of phase ordering and this was consistent with the model which showed that a repetitive additional component would always incorporate the phase ordering effect. In the absence of detectable additivity pure phase re-ordering might alternatively occur as proposed by Sayers. The CNV's of a patient group were also studied and certain tests are proposed as a possible method of diagnosis. The reliability of these tests was not conclusively proved as much larger control and patient groups would be required to do this. An important part of this work involved the introduction of a quantitative method for assessing the effectiveness of methods of removing eye movement artefact from the EEG. This allowed the development of a more extensive correction method which was tested against two other techniques and found to be superior. This correction method will provide the basis for further research and the development of a corrector to be made commercially.Department of Neurological Sciences, Freedom Fields Hospital, Plymout

Development of preparatory activity indexed by the contingent negative variation in children

Objectives The present study investigated the effect of age on task-specific preparatory activation induced by a spatial cue using the central cue Posner’s paradigm. The behavioral responses and the contingent negative variation (CNV) generated between S1 (the warning stimulus) and S2 (the imperative stimulus) were compared between 16 healthy children (8–13 years old) and 17 healthy young adults (18–23 years old). Methods The EEG was recorded from 20 scalp sites of the International 10–20 system. The complete trial period included a central directional cue that was on for 300 m s and an attentive waiting period lasting 1360 m s. Finally, a peripheral target appeared, subtending a visual angle of 4.56° and situated 2.28° eccentrically in the horizontal meridian. The early and late components of the CNV appearing in the period between cue and target were analyzed. Results The CNV of children showed no contralateral cortical activation related to motor preparation. However, the young adults showed contralateral activation to the cue over motor areas. Both children and young adults showed cortical activation in posterior sensory areas, displaying a pattern of activation contralateral to the cue. Also, a positive parietal component appeared in children during the CNV period. Conclusions These results suggest that the motor preparation system in children is less mature than the sensory preparatory system. The children may have used strategies and brain areas different from those of the young adults to prepare for stimuli and responses

Contingent negative variation and its relation to time estimation: a theoretical evaluation

The relation between the contingent negative variation (CNV) and time estimation is evaluated in terms of temporal accumulation and preparation processes. The conclusion is that the CNV as measured from the electroencephalogram (EEG) recorded at fronto-central and parietal-central areas is not a direct reflection of the underlying interval timing mechanism(s), but more likely represents a time-based response preparation/decision-making process

Cerebellum in timing control: Evidence from contingent negative variation after cerebellar tDCS

Background and aims Timing control is defined as the ability to quantify time. The temporal estimation of supra-seconds range is generally seen as a conscious cognitive process, while the sub-seconds range is a more automatic cognitive process. It is accepted that cerebellum contributes to temporal processing, but its function is still debated. The aim of this research was to better explore the role of cerebellum in timing control. We transitorily inhibited cerebellar activity and studied the effects on CNV components in healthy subjects. Methods Sixteen healthy subjects underwent a S1-S2 duration discrimination motor task, prior and after cathodal and sham cerebellar tDCS, in two separate sessions. In S1-S2 task they had to judge whether the duration of a probe interval trial was shorter (Short-ISI-trial:800 ms), longer (long-ISI-trail:1600 ms), or equal to the Target interval of 1200 ms. For each interval trial for both tDCS sessions, we measured: total and W2-CNV areas, the RTs of correct responses and the absolute number of errors prior and after tDCS. Results After cathodal tDCS a significant reduction in total-CNV and W2-CNV amplitudes selectively emerged for Short (p < 0.001; p = 0.003 respectively) and Target-ISI-trial (total-CNV: p < 0.001; W2-CNV:p = 0.003); similarly, a significant higher number of errors emerged for Short (p = 0.004) and Target-ISI-trial (p = 0.07) alone. No differences were detected for Longer-ISI-trials and after sham stimulation. Conclusions These data indicate that cerebellar inhibition selectively altered the ability to make time estimations for second and sub-second intervals. We speculate that cerebellum regulates the attentional mechanisms of automatic timing control by making predictions of interval timing