Contingent Negative Variation Paradigm Research Articles

Impaired sustained attention in groups at high risk for antisocial personality disorder: A contingent negative variation and standardized low-resolution tomographic analysis study.

This study aimed to explore the characteristics of contingent negative variation (CNV) in groups at high risk for antisocial personality disorder. A classic CNV paradigm was used to compare the characteristics of attention maintenance among a group of individuals with conduct disorder (CD group; n = 27), a group of individuals with antisocial personality traits (AP; n = 29), a group of individuals with conduct disorder and antisocial personality traits (CD + AP group; n = 25), and a group of healthy controls (CG group; n = 30), to examine the characteristics of the amplitude and latency of CNV in different processing stages. Results of the event-related potential analysis were as follows: The mean amplitude analysis between 500 and 1,000 ms revealed that the mean CNV amplitudes in the CD + AP group (-1.388 ± 0.449 μV, P < 0.001) were significantly lower than that in the CG group (-4.937 ± 0.409 μV). The mean amplitude analysis between 1,000 and 1,500 ms revealed that the mean CNV amplitude in the CD + AP group (-0.931 ± 0.646 μV) was significantly lower than that in the CG group (4.809 ± 0.589 μV, P < 0.001). The mean amplitude analysis between 1,500 and 2,000 ms revealed that the mean CNV amplitude in the CG group (3.121 ± 0.725 μV) was significantly higher than that in the CD + AP group (-0.277 ± 0.795 μV, P = 0.012), whereas the mean CNV amplitude in the CD + AP group was not significantly different in the AP group (P = 0.168) and CD group (P > 0.05). Source localization results indicated altered activity in frontal-temporal regions. The CNV amplitude characteristics in the CD + AP group and AP group were more consistent and fluctuated around the baseline, indicating the absence of attention maintenance resulted in impairments in attention allocation and motor preparation in the CD + AP group and AP group.

"You Should Praise" - "You Should Kill": The Contingent Negative Variation Indicates Moral Goodness and Badness.

Moral advice (how to behave in life) is often conveyed by short, simple sentence constructions: “You – should – (plus verb with moral meaning).” Yet how moral prescriptions are processed has never been studied from a neurocognitive perspective. The results of this study suggest that the contingent negative variation (CNV) serves as a neural correlate for moral (and immoral) predictive phrases. In step 1, the original CNV paradigm (S1–S2–motor response) was extended using action-demanding three-word phrases taken from everyday contexts (e.g., “Ready–Set–Go”). In step 2, these commands were replaced by abstract words, each phrase then including a verb of moral or immoral meaning (e.g., “You should hope,” “You should praise,” and “You should lie”). During recording, each phrase type (e.g., moral or immoral) was presented blockwise. The task varied according to block order: Participants (n = 19) had to either listen attentively or respond with a finger tap immediately after the final word of a phrase. Electroencephalogram (EEG) data were bandpass filtered (0.1–30 Hz) and analyzed at the onset of the second word, yielding two independent responses: a bilateral CNV and a bilateral motor-related negativity, both decreasing from anterior to posterior. The results show that the CNV is sensitive to phrase constructions of moral resp. immoral valence. Thus, transfer to remote semantic fields seems possible. Importantly, this transfer is combined with a change of time frames, from restricted and highly pragmatic (as in the original paradigm) to indefinite and vague. Thus, a CNV may indicate not only preparation to action but also general guidelines for social life. An N400 occurring as an additional, task-dependent result cannot be sufficiently explained on the basis of the present data.

Higher, faster, stronger: The effect of dynamic stimuli on response preparation and CNV amplitude

The contingent negative variation (CNV) is a slow negative shift in the electroencephalogram (EEG), observed during response preparation. To optimalize the CNV paradigm, this study developed a task using dynamic stimuli and next combined this task with a Go/No-go test. In the first experiment, 19 healthy volunteers were subjected to the classic Traffic light (TL) task and the new dynamic Lines task. In the Lines task, response time was faster and CNV amplitude was larger compared to the TL task. In the second experiment, 20 healthy participants were tested on a Go/No-go version of the Lines task. Response times increased as the probability of response requirement decreased. CNV amplitude was larger when probability of response requirement was higher. In conclusion, the dynamic task promotes response preparation. The new tasks may be especially valuable in groups with attention difficulties (i.e. elderly or ADHD patients).

Cortical Habituation Deficit in Tinnitus Sufferers: Contingent Negative Variation as an Indicator of Duration of the Disease

Cortical attention and habituation parameters are altered in patients suffering from tinnitus. The aim of the study was to quantify cortical attention and habituation parameters in tinnitus patients by recording the contingent negative variation (CNV) response and to correlate amplitudes of different CNV parameters with duration of disease. Twenty patients suffering from tinnitus (median: 44years) and twenty age- and sex-matched healthy controls (median: 41years) were tested by a CNV paradigm. We recorded overall CNV, initial CNV, and terminal CNV and calculated habituation slopes. All CNV parameters were Spearman-correlated with individual duration of disease. Highly significant between groups differences emerged in total (tinnitus: -8.4uV vs. controls: -3.8uV), initial (-11.2 vs. -6.0uV), and terminal CNV (-11.9 vs. -6.5uV) demonstrating higher negative amplitudes in tinnitus patients. Habituation differed in total and terminal CNV, indicating missing habituation in tinnitus patients. Overall CNV (ϱ=-.365) and initial CNV (ϱ=-.529) showed a medium Spearman correlation with duration of disease. We conclude that the correlation between duration of tinnitus and the initial CNV amplitudes indicates an altered state of cortical excitability that can also be observed in more negative CNV-amplitudes in tinnitus patients. We assume that this state indicates a chronicity process in tinnitus disease.

Cluster analysis of behavioural and event-related potentials during a contingent negative variation paradigm in remitting-relapsing and benign forms of multiple sclerosis

BackgroundEvent-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile.MethodsWe investigated MS patients with RRMS and BMS subtypes using event-related potentials (ERPs) acquired in the context of a Posner visual-spatial cueing paradigm. Specifically, our study aimed to assess ERP brain activity in response preparation (contingent negative variation -CNV) and stimuli processing in MS patients. Latency and amplitude of different ERP components (P1, eN1, N1, P2, N2, P3 and late negativity -LN) as well as behavioural responses (reaction time -RT; correct responses -CRs; and number of errors) were analyzed and then subjected to cluster analysis.ResultsBoth MS groups showed delayed behavioural responses and enhanced latency for long-latency ERP components (P2, N2, P3) as well as relatively preserved ERP amplitude, but BMS patients obtained more important performance deficits (lower CRs and higher RTs) and abnormalities related to the latency (N1, P3) and amplitude of ERPs (eCNV, eN1, LN). However, RRMS patients also demonstrated abnormally high amplitudes related to the preparation performance period of CNV (cCNV) and post-processing phase (LN). Cluster analyses revealed that RRMS patients appear to make up a relatively homogeneous group with moderate deficits mainly related to ERP latencies, whereas BMS patients appear to make up a rather more heterogeneous group with more severe information processing and attentional deficits.ConclusionsOur findings are suggestive of a slowing of information processing for MS patients that may be a consequence of demyelination and axonal degeneration, which also seems to occur in MS patients that show little or no progression in the physical severity of the disease over time.

Contingent negative variation as a dopaminergic biomarker: evidence from dose-related effects of methylphenidate

RationaleThe basal ganglia play an important role in motor control, which is dependent on dopaminergic input. Preparation of a motor response has been associated with dopamine release in the basal ganglia, and response readiness may therefore serve as a pharmacodynamic marker of dopamine activity.MethodsWe measured response readiness using the amplitude of the contingent negative variation (CNV), a slow negative shift in the electroencephalogram. The CNV is evoked in a paradigm in which a warning stimulus (S1) signals the occurrence of the imperative stimulus (S2) 4 s later, to which the participant has to respond. CNV was assessed in healthy volunteers after administration of placebo or 10, 20 or 40 mg of methylphenidate, a catecholamine re-uptake blocker which primarily enhances the synaptic concentration of dopamine and to a lesser extent also noradrenaline. In addition, participants filled out two visual analogue scales measuring subjective ratings of mood and alertness: Profile of Mood States and Bond and Lader.ResultsMethylphenidate dose dependently increased CNV amplitude and decreased reaction times. Furthermore, participants reported improved mood, feeling more alert, vigorous and content and less angry and tired after methylphenidate.ConclusionsThese results indicate that dopamine availability increases response readiness as measured by the CNV paradigm. The CNV appears to be a good candidate biomarker for assessing changes in dopaminergic function by treatments that either directly or indirectly target the dopaminergic system.

Cortical inhibition at rest and under a focused attention challenge in adults with migraine with and without aura

We aimed to further elucidate the functional and attentional regulation of cortical excitability in migraine patients. We investigated the cortical silent period (CSP) after transcranial magnetic stimulation as a measure of cortical inhibition under three conditions: resting condition, cortical preactivation during reaction preparation, and during the post-processing of a motor response using a visual contingent negative variation paradigm in adults with migraine with aura, migraine without aura and healthy controls. CSP was reduced in individuals with migraine with aura and unaffected in those with migraine without aura under resting conditions. Along with the intensity of transcranial magnetic stimulation, CSP increased equally in all groups (equal slopes). Furthermore, the functional challenge by a contingent negative variation task requiring focused sustained attention led to a comparable reduction of CSP duration in all groups. Our data provide further hints towards the conclusion that a specific cortical inhibition deficit in migraine with aura but not migraine without aura is due to a tonic imbalance and not related to increased reactions to phasic stressors. Given that CSP at rest is related to GABA-ergic inhibition whereas the CSP reduction during late contingent negative variation is thought to be related to dopaminergic disinhibition in the basal ganglia, our results point towards reduced GABA-ergic cortical inhibition related to dysfunctional thalamo-cortical loops, especially in migraine with aura.

Effects of Rizatriptan on the Contingent Negative Variation in Healthy Women

The effect of the antimigraine drug rizatriptan on the amplitude and habituation of the contingent negative variation (CNV) in healthy women was examined in a randomized, double-blind, placebo-controlled trial. The test persons were assigned either to a drug (n = 20) or a placebo group (n = 20). The CNV was recorded three times: before, directly after, and 24 h after drug or placebo intake. The CNV paradigm was presented in a standard, a cued and a choice version. Rizatriptan led to an increase of CNV amplitude that depended on the level of difficulty of the task. Whereas there was no drug effect in the standard version, an amplitude increase was obtained mainly in the choice task. The results are in line with the ceiling theory of migraine, which assumes a rise of CNV amplitude if the serotonin level is lowered.

How does a short history of spinal cord injury affect movement‐related brain potentials?

Brain plasticity following spinal cord injury (SCI) has been studied by a wide range of neurofunctional techniques, which tend to have low temporal resolution or overlook cognitive preparatory processes. This study tried to overcome both limitations by recording the movement-related brain potentials using an experimental task somewhat similar to the contingent negative variation paradigm. The aim was to look for amplitude or topographic distribution changes at an early stage of the SCI. Hence, the brain electrical activity of patients who had a clinical history of less than 6 months of paraplegia was recorded and compared with that of two groups of healthy volunteers. None of the patients was able to move their toes, but they were asked to prepare to carry out this movement and to try to execute it in the same way as one of the control groups. The other control group was instructed to prepare to conduct the same movement but not to execute it. Results did not show significant differences in the readiness potential between patients with paraplegia and both controls. However, the readiness potential topography observed in patients was more similar to that of healthy participants who conducted the movement, whereas a greater similarity was found in the motor potential between patients and healthy participants who did not carry out the movement. These findings suggest that neurofunctional changes that take place in the brain after a SCI may be shown earlier by the motor potential than by the readiness potential.

The effect of response type (motor output versus mental counting) on the intracerebral distribution of the slow cortical potentials in an externally cued (CNV) paradigm

Objective Previous surface CNV studies including a hand motor output have suggested that the late phase of the CNV reflects the preparation of the sensorimotor cortices involved in the motor output given the same similarity in scalp potential distribution with readiness potential. However, the poor spatial resolution of the scalp recorded CNV data prevented a definitive conclusion. This intracerebral study allowed us to test this hypothesis using a CNV paradigm in which a non-motor task is used as a reference. This study concerned the intracerebrally located generators of the Contingent Negative Variation in two different paradigm settings: (i) motor output required, (ii) silent counting required (non-motor control condition). Methods Stereoelectroencephalography (SEEG) recordings of the contingent negative variation (CNV) in a somato-somatosensory stimulation paradigm with a motor or counting task were taken from nine patients with drug-resistant epilepsy. The intracerebral recordings were taken from 25 cortical areas in both hemispheres (supplementary motor area-SMA; the cingulate gyrus; the orbitofrontal, premotor and dorsolateral prefrontal cortices; lateral temporal cortex, amygdalohippocampal complex; and the parietooccipital cortex). Results The slow waves were generated in the SMA, the premotor, dorsolateral, and orbitofrontal cortices, the cingulate gyrus, and parts of the lateral temporal, mesial temporal structures and parietal cortex. We found a significant difference between the two tasks in the CNV potential generation. The task with the motor output produced significantly higher numbers of CNV potential generators when compared to the task with silent counting. Conclusions The CNV potential generators varied between motor and non-motor tasks. The intracerebral distribution of the potentials linked with expectation is task dependent. Our main conclusion is that the executive network is more active during the motor task than during counting task.

Stereotyped topography of different elevated contingent negative variation components in children with migraine without aura points towards a subcortical dysfunction

Increased negativity during contingent negative variation (CNV) is thought to reflect abnormal neural activation in adult migraineurs’ attention related processing. Findings in childhood and adolescence have yielded less clear results. This study characterizes the age-dependent development of CNV topography in migraine during childhood in order to elucidate the origin and cerebral generators of described CNV elevations. A large sample of children with primary headache (migraine with/without aura, tension type headache) and healthy controls aged 6–18 years was examined in a CNV paradigm using 64-channel high resolution DC-EEG. Patients were tested for diagnose-related topographic group differences of initial CNV (iCNV), late CNV (lCNV) and postimperative negative variation (PINV). All three CNV components of 6–11-year-old migraineurs without aura showed elevated negativity over the supplementary motor area (SMA) and around the vertex. Migraine children lacked age-dependent development of late CNV around Cz as previously reported. However, they showed a normal development of late CNV over pre-/primary motor cortex (MI). There was no marked elevation of iCNV amplitude over frontal areas (orienting reaction) nor specific amplitude elevations over “motor” or “sensory” areas during sustained attention (late CNV). Additional “pre-mature” activation e.g., in the locus coeruleus (leading to diffuse cortical activation summing up to a maximum over the vertex) or the basal ganglia (interacting with SMA) explained the rather stereotyped CNV elevation around the vertex better than a specific implication of the cortical systems responsible for orienting, motor preparation or sensory attention.

1405 The effect of response type on the Intracerebral Distribution of the slow cortical potentials in contingent negative variation paradigm

1405 The effect of response type on the Intracerebral Distribution of the slow cortical potentials in contingent negative variation paradigm

Cognitive potentials in the basal ganglia-frontocortical circuits. An intracerebral recording study.

We studied cognitive functions related to processing sensory and motor activities in the basal ganglia (BG), specifically in the putamen and in cortical structures forming the BG-frontocortical circuits. Intracerebral recordings were made from 160 brain sites in 32 epilepsy surgery candidates. We studied P3-like potentials in five different tests evoked by auditory and visual stimuli, and two sustained potentials that are related to cognitive activities linked with movement preparation: BP (Bereitschaftspotential) and CNV (contingent negative variation). We compared the presence of a potential with a phase reversal or an amplitude gradient to the absence of a generator. All of the studied cognitive potentials were generated in the BG; the occurrence in frontal cortical areas was more selective. The frequency of all but one potential was significantly higher in the BG than in the prefrontal and in the cingulate cortices. The P3-like potentials elicited in the oddball paradigm were also more frequent in the BG than in the motor/premotor cortex, while the occurrence of potentials elicited in motor tasks (BP, CNV, and P3-like potentials in the CNV paradigm) in the motor cortex did not significantly differ from the occurrence in the BG. The processing of motor tasks fits with the model by Alexander et al. of segregated information processing in the motor loop. A variable and task-dependent internal organisation is more probable in cognitive sensory information processing. Cognitive potentials were recorded from all over the putamen. The BG may play an integrative role in cognitive information processing.

Effect of Gumchewing with CNV Paradigm on Event-related Potential

The psychophysiological effects of gumchewing were studied by event-related potential (ERP) in 12 healthy volunteers (six males and six females) aged 20–57 years. ERP was recorded with the Tentwenty electrode system from the contingent negative variation (CNV) paradigm after gumchewing and resting, and 5 event-related potential components (N100, P300, Early CNV, Middle CNV, Rate CNV) were extracted for principle component analysis. N100 peak amplitude after gumchewing was significantly larger than that after resting at F3, FZ, F7, and F8, (p<0.05). Early CNV amplitude after gumchewing was significantly larger than that after resting at FZ, F7, C4, P3, T6 and O2 (p<0.05). Reaction time after gumchewing was significantly shorter than that after resting. These results suggested that gumchewing raises general attention and the arousal level with precision.

Event-related potentials, CNV, readiness potential, and movement accompanying potential recorded from posterior thalamus in human subjects. A SEEG study

Intracranial recordings were obtained from three patients with intractable chronic pain who underwent analgesic electrical stimulation of the contralateral thalamus. Multilead electrode made it possible to record from several thalamic nuclei. The electrode was targeted into the ventroposterolateral (VPL) nucleus of the thalamus. During separate recording sessions, the following tests were performed: somatosensory evoked potentials (SEP) of the median or posterior tibial nerve, event-related cognitive potentials (auditory oddball P3 wave), readiness potential (RP) and contingent negative variation (CNV) using auditory warning (S1) and visual imperative (S2) stimuli. The movement accompanying potential (MAP), which was present in the VPL in all but one of the recordings, behaved as a far-field potential. Recordings obtained from the VPL confirmed its established role as a relay nucleus, processing somatosensory information to the primary somatosensory cortex. The VPL generated the ‘thalamic’ SEP, which was the only potential regularly recorded in this nucleus. In the recordings from one patient (No. 3), auditory and visual evoked potentials of the CNV protocol, peaking at approximately 300 ms, were obtained from the VPL and appeared to be generated in situ. Neither RP, CNV nor ˈoddballˈ ERPs appeared in the VPL. From the pulvinar, only a visually evoked potential was recorded. Oddball P3, RP, CNV, and middle and long latency auditory and visual potentials (evoked in the CNV paradigm) appeared to be generated ‘dorsally’ to the VPL, probably in the nucleus posterolateralis (PL). This structure may therefore be involved in both the processing of afferent information and in cognitive operations.

Contingent negative variation and Dex-CRH test in patients with major depression

E€ects of corticosteroid secretion on cognitive information processing have been reported in studies with animals (Vicedomini et al., 1990; Oitzl and de Kloet, 1992; Sandi and Rose, 1994), healthy human subjects (Wolkowitz et al., 1990, 1997), patients with Cushing's syndrome (Whelan et al., 1980) or treated with corticosteroids (Ling et al., 1981; Varney et al., 1984). In depression hypothalamic pituitary adrenal (HPA) axis dysregulation is the major neuroendocrine ®nding (Holsboer and Barden, 1996) and cognitive impairment is frequently observed (Weingartner, 1982; Veiel, 1997), however, only a limited number of studies addressed the relationship between HPA axis dysregulation and cognitive dysfunction in depression. Findings of these studies suggest an association between cognitive impairment assessed by neuropsychological tests and nonsuppression of cortisol in the dexamethasone suppression test (DST) (Siegel et al., 1989, Wolkowitz et al., 1990). The contingent negative variation (CNV), an event related potential, provides a tool to evaluate the central neurophysiological activity underlying cognitive processes of attention (McCallum and Walter 1968). In addition, CNV amplitudes were inversely correlated with severity of depression (Papart et al., 1990). Furthermore, nonsuppression in DST was associated with alterations of CNV amplitude and latency in depressed patients (Timsit-Berthier et al., 1986). In a recent study by our group (Heimberg et al., 1999) a complex CNV paradigm was applied which included a variation in the intensity of attention. Compared to healthy controls, depressed patients presented with a slightly decreased CNV in the target, but a substantial CNV in the nontarget-condition, which was not observed in healthy subjects (Heimberg et al., 1999). In eight inpatients of this study [6 females, 2 males, age: 51.8 11.3 years (mean S.D.)] a combined dexamethasone-corticotropin releasing hormone (Dex-CRH) test (Holsboer et al., 1987), which provides an increased sensitivity compared to the DST (Heuser et al., 1994) was additionally performed. All patients were in an acute phase of major depression (between the ®rst and second week after admission to the depression unit) and were treated with a monotherapy of 200 mg trimipramine for at least 5 days before the examination of the CNV and seven days before the Dex-CRH test. Severity of depression was assessed by Hamilton Rating Scale of Depression (HDRS, Hamilton, 1967). The CNV paradigm, a choice-reaction task, which included a preceding warning period of one second, consisted of a series of 72 ®gures of three complex ®gures presented tachistoscopicly. One third of the series consisted of three identical ®gures (response-relevant condition=RR) and had to be con®rmed by button press immediately after the presentation of the third identical condition (target condition). In the two further thirds of the series either two of the ®gures were identical or all ®gures di€ered (response irrelevant condition=RI). In the response-irrelevant condition (RI) no button press was required. Therefore, both conditions (RRand RI-condition) di€er to a large extent in the requirement of attentional demanding processes. CNV prior to the second ®gure served as the baseline. Monopolar EEG was recorded with the electrode positions Fz, Cz, Pz and two connected electrodes at the mastoid position as reference. Maximal amplitude of CNV was measured between 1200 and 1500 ms after onset of the second ®gure (S1) and before the third ®gure (S2); for further details see Heimberg et al. (1999). In depressed patients (HDRS-score, 21.6 5.9) CRH stimulated cortisol in the Dex-CRH test was increased by trend compared to healthy controls matched by age

Shortening of the cortical silent period following transcranial magnetic brain stimulation during an experimental paradigm for generating contingent negative variation (CNV)

Objectives: We investigated changes in the cortical silent period (CSP) following transcranial magnetic cortical stimulation (TCMS) during a standard paradigm which was designed to evoke contingent negative variation (CNV) in ten normal subjects.Methods: We recorded the motor evoked potentials (MEP) and CSP during the inter-stimulus interval (ISI) of a CNV paradigm in ten normal subjects. The CNV paradigm consisted of a visual warning stimulus (S1) followed by a visual response stimulus (S2). The CSP following TCMS on the hand motor area was recorded from mildly contracted first dorsal interosseous muscles.Results: The CSP was significantly shortened during the ISI (P<0.01, t test) with a highly significant correlation with the TCMS timing during the ISI (P<0.02, Spearman's correlation coefficient), while the MEP amplitude and latency were unchanged.Conclusions: The results suggested that shortening of the CSP was associated with neural processes related to preparation for voluntary movement during the paradigm.

Contingent Negative Variation and Attention in Schizophrenic and Depressed Patients

Contingent negative variation (CNV) is supposed to be a psychophysiological indicator of attention and arousal. Both have been reported to be deteriorated in schizophrenic and depressed patients. Thirty-four patients with major depression, 43 patients with schizophrenia and 49 healthy subjects were investigated during acute illness with a complex three-stimulus go/no-go task which requires different states of attention: trials consisted of three complex figures that were tachistoscopically presented. Three identical figures had to be confirmed by pressing a button (target condition). CNV was measured: (1) after the first figure waiting for the second (baseline condition), (2) after two identical figures waiting for the third (response-relevant condition), (3) after two different figures waiting for the third (response-irrelevant condition). The response-relevant condition compared to baseline significantly intensified CNV in healthy controls and to a minor extent in depressed patients but not in schizophrenics. In the response-relevant conditions in healthy controls, CNV was significantly reduced compared to the response-relevant condition. This clear discrimination between response-relevant and response-irrelevant conditions was not observed in either group of patients. Thus, the applied CNV paradigm was able to discriminate schizophrenic and depressed patients from healthy controls. Furthermore, subtle differences between schizophrenic and depressed patients were detected, reflected by the different CNV development across experimental conditions.

Inter-hemispheric lateralization of event related potentials; motoric versus non-motoric cortical activity

To study hemispheric lateralization of cortical potentials associated with motoric and non-motoric function, cortical activity was recorded accompanying either finger extension or saccadic eye movements in a contingent negative variation (CNV) paradigm. Subjects viewed computer-generated pacing stimuli, presented in the left visual hemi-field, and were instructed to either initiate or inhibit a motor response following an imperative signal. Motoric lateralization was assessed by means of the lateralized readiness potential (LRP). In addition, a measure complementary to the LRP was introduced to investigate non-motoric lateralization (NML). Contralateral inter-hemispheric lateralization was evident in the LRP preceding finger movement, but was absent prior to eye movements. However, pre-saccadic cortical response profiles did exhibit a right hemispheric, non-motoric lateralization (NML) during stimulus presentation. Comparable non-motoric lateralization was found for finger extension. Results of the present study suggest that non-motoric lateralization may be a contributing factor to the frequently reported inter-hemispheric asymmetry preceding self-initiated saccadic eye movements. Results of the present study also suggest that the latter may be related to a covert shift of visuospatial attention toward the saccadic target. Associated shifts of attention are suppressed in a CNV paradigm, where attentional focus is primarily on the CNV stimulus during the pre-saccade period.

Event-related desynchronization to contingent negative variation and self-paced movement paradigms in Parkinson's disease.

The event-related desynchronization (ERD) to voluntary movement is an indicator of cortical activation with a high time resolution and a specific spatial representation. We have evaluated 10 patients affected by Parkinson's disease (PD), free from L-dopa treatment for at least 12 hours, and 10 control subjects. Each subject underwent ERD examination during self-paced movement (SPM) and during contingent negative variation (CNV) paradigms. ERD was measured as the percentage decrease of alpha band power and calculated for frequency bands of 1 Hz, ranging between 8 and 12 Hz. For group comparisons, the frequency showing the highest ERD was selected for each subject and for each side. In the control group, ERD in the CNV paradigm began over the contralateral centroparietal electrodes 1475 ms before movement onset of the right hand and 1375 ms for the left. In the SPM paradigm, ERD started over the contralateral central electrodes 2150 ms and 1775 ms before movement onset of the right and left hand, respectively. In the PD group, ERD started over the contralateral central areas 800 ms and 475 ms before movement onset of the right and left hand, respectively, for CNV paradigm and 1200 ms and 750 ms for the right and left hand, respectively, for SPM paradigm. Therefore, contralateral ERD began closer to movement onset in PD compared with the control group in both paradigms. ERD over the sensorimotor areas ipsilateral to the movement was not significantly different in PD compared with the control group. The finding of delayed contralateral ERD in PD is according to the view that functional cortical activation related to movement preparation is impaired in PD. The lack of group differences in the onset of ipsilateral ERD, which appears close to movement execution than contralateral ERD both in normal subjects and in PD, suggests that different mechanisms may be involved in generating ERD over the hemispheres ipsilateral and contralateral to the movement, and that only the latter are impaired in PD.