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PubMed1996

CNV, PINV and probe-evoked potentials in schizophrenics.

Distractibility and temporal modulation of attention in schizophrenics were studied using a visual reaction time task with additional auditory probe stimuli during the forewarning period or between trials. The probes were thought to exert a distracting influence, especially on schizophrenics, and at the same time they generated auditory EPs which allowed to track the modulation of cortical excitability during response preparation. The midline distribution of the terminal contingent negative variation (tCNV) and the amplitude of the postimperative negative variation (PINV) were clearly different in 20 DSM III-R schizophrenics, as compared with 20 alcoholics and 20 normal controls. In schizophrenics, the more frontal distribution of the tCNV was associated with a higher degree of psychopathology (measured with the Brief Psychiatric Rating Scale) and with delayed reactions. Probes between trials reduced tCNV and PINV in all subjects alike. However, this effect could not be attributed to distraction, because reaction times were faster in these trials, possibly due to an alerting effect of the auditory probes. The N100 and P300 amplitudes to probes in the forewarning period, i.e., during the negative potential shift of the CNV, were significantly enhanced in all groups. Apparently there is a state of increased cortical excitability during the CNV which is not selectively "tuned" toward relevant stimuli. In schizophrenia, the temporal and topographical regulation of this excitability is disturbed.

Adult↗
PubMed1981

EEG and cardiac correlates of neuroticism: a psychophysiological comparison of neurotics and normal controls in relation to personality.

In the context of Eysenck's theory of personality the contingent negative variation (CNV) was recorded in 60 psychiatric patients (30 introverted and 30 extraverted neurotics) and 60 normal controls (30 stable extraverts and 30 stable introverts) under three experimental conditions, i.e. the standard CNV-paradigm (St: tone-light-MR) and two discrimination tasks. In these tasks either S1 (info S1) or S2 (info S2) contained task-relevant information with respect to the motor response (MR). At a 4 sec CNV-interval the O- and E-wave, the P300 elicited by S1, the alpha power, the heart rate and the heart rate variability were measured. The EEG, recorded from Cz to the linked earlobes, P4 vs. O2 and the EOG were sampled at a frequency of 100 c/s over a 12 sec epoch (starting 8 sec before S1 till the onset of S2). The increase in informative properties of S1 (as is the case during 'info S1') resulted in enhanced amplitudes (and increased latencies) of O-wave and P300, producing evidence that these two slow waves are related to cortical orientation. The E-wave is not influenced, as expected, by the informative properties of 'info S2' and there is no linear relationship between task complexity and the E-wave. Reaction time increased from 'St' to 'info S2' as did the heart rate. The present results indicate that there is no simple way to characterize CNV-components that can best distinguish neurotics from controls. Neurotics showed during all three conditions shorter P300 latencies than controls indicating that the P300 seems to be a better ERP-parameter than the CNV-components to differentiate between neurotics and controls.

Adolescent↗
PubMed1997

Effects of reduction in arousal level caused by long-lasting task on CNV.

The present study aimed at investigating an inverted-U relationship between contingent negative variation (CNV) and arousal level by examining the effects on CNV of gradually reduced arousal level by long-lasting task. The subjects conducted a simple reaction time task consisting of warning stimuli (S1) and imperative stimuli (S2). This task consisted of 200 trials and lasted about 40 minutes. During this task, spontaneous EEG before S1 and SPL (skin potential level) were measured as indicators for arousal level. The 200 CNV, EEG and SPL data were classified into 5 blocks each of which included 40 trials of data. Analysis was made in seven subjects in whom reduction in the arousal level in long-lasting task was shown by increase in the relative power values of alpha waves before S1 and decrease in the SPL. As a result, the amplitude of early CNV at Fz was observed to increase from the earlier half phase (block 1) to the middle phase (block 3) and to decrease from the middle phase (block 3) to the latter half (block 5). In the middle phase, the amplitude was the greatest. The low amplitude of early CNV in the early half of the task (block 1) was inferred to have been induced by excessive arousal state because of the low relative power values of alpha waves and the high SPL at this time. On the other hand, the low amplitude in the later phase (block 5) was inferred to have been induced by reduction in arousal level because of the high relative power values of alpha waves and the low SPL. These results suggested that CNV amplitude and arousal level was in an inverted-U relationship.

Adult↗
PubMed1983

Correlates of cerebral event-related slow potentials and psychopathology.

The study explored associations between the cerebral event-related slow potentials (ERSP) and psychiatric symptoms and syndromes as reflected by the Present State Examination (PSE) in 36 randomly selected psychiatric in-patients. Independent raters measured the readiness potential (RP), contingent negative variation (CNV) and post-imperative negative variation (PINV) in terms of their amplitude and duration. The 360 individual PSE items were grouped into units of analysis (UA) and further collapsed into groups of units of analysis (GUA). Canonical correlations were computed between two sets of variables (psychological and electrophysiological). Kendall's rank-order correlation was used as the main statistical approach. Some psychotic signs were associated with increased PINV amplitude. Obsessive thoughts, ideas of reference and verbal hallucinations correlated with longer PINV duration. Hopelessness and suicidal thoughts (affect-laden thoughts) as well as first-rank Schneiderian symptoms (FRS) were negatively correlated with CNV amplitude. The results support the hypothesis that CNV and PINV, alone or in combination, can be used to indicate the presence or absence of identifiable psychiatric symptoms and syndromes. The implications of electrophysiological correlates of psychopathology for psychiatric nosology and for the validity of psychiatric symptoms and syndromes were discussed.

Adolescent↗
PubMed2000

[Reliability of electrogustatory threshold--electrogustometry using CNV].

CNV (contingent negative variation), an event-related potential, is induced when an oncoming imperative stimulus (S2) is anticipated after recognition of a warning stimulus (S1). With this in mind, we assessed the usefulness of electrogustometry using CNV as an objective gustatory test with an electric gustatory stimulus as a warning stimulus, S1. A gustatory test was performed on a total of 100 sides of the tongue in 50 subjects. Excluding no response cases on 5 sides in 5 subjects, the CNV threshold was successfully determined on 95 sides in 50 subjects. When the CNV threshold values obtained and the conventionally measured subjective threshold values were compared, a very high correlation was demonstrated between the two thresholds, with a correlation coefficient of 0.961. To assess the reliability of the CNV threshold, three additional measurements on 5 sides in 5 subjects with normal subjective threshold values were performed on different days, and the CNV threshold value variation among the three measurements in all 5 subjects never exceeded 13 microA. Separately, subjective threshold and CNV threshold values were compared in 4 patients with facial palsy (hence with gustatory abnormality) who consented to a follow-up examination. The difference between the subjective threshold and CNV threshold values in all 4 patients never exceeded 10 microA. These findings demonstrate that the reliability of the CNV threshold is satisfactory. Next, a gustatory imitation experiment was performed to assess the usefulness of electrogustometry using CNV as a means of detecting gustatory abnormality malingering. The experiment was performed on a total of 6 subjects: 3 physicians with knowledge of CNV (knowledge group) and 3 others with no knowledge of CNV (no-knowledge group). The differences between the imitated threshold and the subjective threshold values in all of these subjects never exceeded 10 microA, and the difference between imitated threshold and CNV threshold values never exceeded 13 microA. Comparison between the knowledge group and the no-knowledge groups showed that the imitated threshold values were very close to the subjective threshold and CNV threshold values. Based on the above results, it was concluded that gustometry using CNV is useful and can serve well as a method of objective evaluation of gustatory sensation. The results also suggested that it will be useful in diagnosing malingering.

Adolescent↗
PubMed2001

Basal ganglia involvement in sensory and cognitive processing. A depth electrode CNV study in human subjects.

OBJECTIVE: Intracranial recordings were taken from the basal ganglia (BG) in order to explore the possible role of the BG in the cognitive processing of sensory information. METHODS: Ten patients with intractable temporal lobe epilepsy, who were candidates for epilepsy surgery, underwent intracranial recordings with depth electrodes. A frontal approach was used for the insertion of diagonal depth electrodes into the amygdalo-hippocampal complex (AH complex). These electrodes passed through the BG. The putamen was explored in 8 patients; the nucleus caudatus and pallidum were explored in two patients. The contingent negative variation (CNV) paradigm was tested using auditory warning stimuli and visual imperative stimuli followed by a hand flexion. The auditory and visual middle and late latency potentials evoked by the warning and imperative stimuli were analyzed. RESULTS: (1) Auditory evoked potentials (EPs): the amplitude potential gradient was observed with latencies of (a) 150-195ms (9 patients); (b) 215-290ms (9 patients); and (c) 350-600ms (10 patients). Negative potentials, with latencies of 100 and 110ms were observed in two patients. (2) Visual EPs: (a) 160-195ms (9 patients); (b) 210-295ms (9 patients); and (c) 330-550ms (7 patients). Negative potentials with latencies between 100 and 120ms were observed in 4 patients. CNV was obtained from the BG in 8 patients; a phase reversal was observed twice. CONCLUSIONS: (1) The BG generate middle and late latency EPs in a cognitive paradigm linked to the motor task. (2) The BG generate CNV. (3) The BG could play an integrative role in the processing of sensory, cognitive, and motor information.

Acoustic Stimulation↗
PubMed2005

[Psychophysiological basis of smells].

There has been an increase in the use of psychophysiological techniques, especially event-related potentials (ERPs) to evaluate the effects of odor on the central nervous system. In the study of ERPs related to odor, there are two main methods of the odor presentation: (1) to investigate the olfactory ERP (OERP) or chemosensory ERP (CSERP), that is to calculate electrophysiological responses to odor stimulation as a trigger; (2) to compare ERP of mental functioning during the odor exposed condition with that of no odor exposure. The amplitude of contingent negative variation (CNV) varies with the odorant being present, when the odor is presented as a trigger and when it is administrated during a task. It is suggested that CNV changes depend on not only the odorant but the anticipation, expectation and emotion of the subject. The latency of the N1 component becomes shorter with increasing concentrations of odors. The N1 amplitude does not depend on the odor concentration while the amplitude of the auditory N1 strongly depends on the stimulus intensity. There is only one report that the olfactory mismatch negativity (MMN) is present in the CSERP. On the other hand, auditory MMN is not affected by odor administration. In relation to the P3 component, rare odors evoked a larger amplitude in contrast to frequent odors, as well as P3 evoked by other modalities. These ERP studies with odors are expected to be applied to such clinical settings as the differentiation between the anosmic patients and normosmic persons, the functional evaluation of patients with brain tumors, the earlier detection of dementia, and the objective evaluation of aromatherapy.

Aromatherapy↗
PubMed1994

Event-related and motor responses to probes in a forewarned reaction time task in schizophrenic patients.

Surface-negative brain potentials indicate increased excitability of the underlying cortical neural networks. Consequently, deviant patterns of event-related potentials in schizophrenic patients reveal an atypical regulation of cortical excitability. Twelve patients with a chronic schizophrenic disorder and 12 matched control subjects were investigated using a probe paradigm: A contingent negative variation (CNV) was evoked in a forewarned reaction time paradigm. Clicks were presented before, during and after elicitation of the CNV. Click-evoked responses allow one to 'probe' the current brain state, particularly neuronal excitability, which is also reflected by the slow potentials. During the measurements, subjects pressed one button in response to the offset of the visual warning stimulus and a different button in response to the acoustic probes, the latter button press being a behavioral indication of the brain's excitability. In the forewarned reaction time task, patients developed a CNV with a frontal maximum, while the CNV in control subjects was predominantly centro-parietal. This atypical topographical pattern of the CNV may indicate a different spatio-temporal regulation of cortical preparatory processes in schizophrenics. Motor responses were accelerated during negative potential shifts in both patients and controls, with responses being slower overall in patients. In patients, probe-evoked potentials revealed a smaller N100, but a larger P300, than in controls. The covariation of these brain waves with slow potentials, however, turned out to be similar for both groups.

Adult↗
PubMed1987

Complex event-related potentials (P300 and CNV) and MSLT in the assessment of excessive daytime sleepiness in narcolepsy-cataplexy.

The P300 and contingent negative variation (CNV) evoked potential (EP) paradigms were performed by 12 untreated narcoleptics and controls immediately prior to each nap of the Multiple Sleep Latency Test (MSLT) in order to assess whether they might hold promise as rapid quantitative techniques to assess excessive daytime sleepiness. The Stanford Sleepiness Scale (SSS) was also completed across test days and immediately before and after both the evoked potential recordings and MSLT naps. MSLT findings confirmed shorter sleep latencies and frequent SOREMPs in narcoleptics and a strong mid-afternoon increase in sleepiness based upon pressure for NREM sleep in both groups. On SSS narcoleptics were sleepier and they showed greater increase in sleepiness induced by the EP tests and greater sleepiness reduction by the MSLT naps. In the P300 paradigm, narcoleptics showed smaller component P3 amplitudes and larger P1 amplitudes. In the CNV paradigm, N1 latencies were greater in narcoleptics to both S1 and S2 and the post-CNV negative component was larger: but no significant differences were seen for the main CNV measures of negativity amplitude in the first or second halves of the response. The P300 paradigm but not the CNV, therefore, appeared to be a sensitive EP measure of sleepiness. Finally, EP components in both the P300 and CNV paradigms showed time-of-day (circadian) differences between narcoleptics and controls.

Acoustic Stimulation↗
PubMed1994

The self-regulation of slow potential shifts and evoked potentials: interrelationships in response to somatosensory stimulation.

Research on the effects of the self-regulation of event-related potentials (ERP) has failed to investigate the possible interactions and contributions of slower cortical events such as contingent negative variations (CNV) and slower DC level changes. The present study attempted to investigate such interactions by independently conditioning the ERP 200 ms poststimulus (P200) and the CNV while recording both potentials simultaneously; DC level measures were also recorded. 30 subjects attempted to increase (uptraining) or decrease (downtraining) either P200 or CNV in response to sub-painful somatosensory stimulation in a biofeedback paradigm. Following the training sessions, P200 downtrainees reported a significant decrease in their detection thresholds for the somatosensory stimuli (i.e., increased sensitivity). These results agree with some prior findings that decreased ERP amplitude in individuals is indicative of greater sensitivity in subjective pain reports. Although uptraining resulted in larger P200 amplitudes than downtraining, the difference in amplitudes between groups was not significant. CNV uptrainees achieved a higher level of pain tolerance following training. The increased CNV negativity may be associated with increased specific attentional processes that facilitate the subjects' control of, or response to, pain. CNV trainers showed a significant interaction of training over blocks of trials. Generally, there was a significant inverse correlation of P200 and CNV; as CNV amplitude became more negative, the P200 amplitude increased. DC negativity level increased over blocks for all conditions. Results indicate a complex relationship between P200, CNV and pain sensitivity. Both P200 and CNV processes are involved in pain perception, but in apparently different ways, i.e., P200 with sensitivity and CNV with tolerance.

Adolescent↗
PubMed2003

When time is up: CNV time course differentiates the roles of the hemispheres in the discrimination of short tone durations.

Numerous studies have suggested that the CNV (contingent negative variation), a negative slow wave developing between a warning and an imperative stimulus, reflects, among other things, temporal processing of the interval between these two stimuli. One aim of the present work was to specify the relationship between CNV activity and the perceived duration. A second aim was to establish if this relationship is the same over the left and right hemispheres. Event-related potentials (ERPs) were recorded for 12 subjects performing a matching-to-sample task in which they had to determine if the duration of a tone (490 ms, 595 ms, 700 ms, 805 ms, and 910 ms) matched that of a previously presented standard (700 ms). CNV activity measured at the FCZ electrode was shown to increase until the standard duration had elapsed. By contrast, right frontal activity increased until the end of the current test duration, even when the standard duration had elapsed. Moreover, for long test durations (805 ms and 910 ms), correlations were observed between CNV peak latency and subjective standard, over left and medial frontal sites. We propose that left and medial frontal activity reflects an accumulation of temporal information that stops once the memorized standard duration is over, while right frontal activity subserves anticipatory attention near the end of the stimulus.

Adolescent↗
PubMed2006

On the relation of movement-related potentials to the go/no-go effect on P3.

According to Simson et al. [Simson, R., Vaughan, H.G., Jr., Ritter, W., 1977. The scalp topography of potentials in auditory and visual go/nogo tasks. Electroencephalography and Clinical Neurophysiology 43, 864-875], the difference between no-go P3 and go-P3 (the go/no-go effect) is due to overlap of P3 onto the return of the preceding contingent negative variation (CNV) in no-go trials and onto the continuing CNV in go trials. Similarly, according to Kok [Kok, A., 1986. Effects of degradation of visual stimuli on components of the event-related potential (ERP) in go/nogo reaction tasks. Biological Psychology 23, 21-38], the go/no-go effect is due to movement-related negative potentials, in particular contralateral negativity, adding with P3 in go trials. To investigate these notions, we studied how CNV, go-P3 and no-go P3 are lateralized at fronto-central sites when the side of the response varies across trials, comparing these effects between hand movements and eye movements and delineating them more precisely for hand movements with multichannel recordings. The go/no-go effect was larger and contralaterally lateralized with hand movements than with eye movements. Dipole analysis dissected its components into a large contribution of the medial cingulate gyrus, into activity of motor areas contralateral to the cued hand and a left-frontal source. Motor-related portions of the effect seemed to build upon and extend motor-related components included in CNV. Results provide support for the notion that the go/no-go effect is related to movement-related potentials. We suggest that go-P3 and no-go P3 are characterized by addition and reduction of motor-related activation to the core P3.

Adult↗
PubMed1992

[Event-related negativity and alpha band desynchronization in motor reactions].

The foreperiod of a motor reaction to an impending stimulus is accompanied by a slow negative wave of the event-related potential, the "contingent negative variation" (CNV), when the imperative stimulus follows at a fixed interval to a warning stimulus. Using similar experimental paradigms, an event-related desynchronization (ERD) in the alpha range occurs indicating cortical activation before and during motor acts. Both EEG-parameters were quantified for four subjects using the following experimental design: One second after a non-informative warning signal (WS) a cue was presented that indicated by which hand the subject had to respond quickly after presentation of a reaction stimulus (RS); subjects were requested to respond by pressing a button with their left or right thumb. EEG-signals were recorded unipolarly from 17 electrodes. Average ERPs and ERD were computed for all electrode sites for trials with left and right hand movements, respectively, and topographically displayed in simultaneous amplitude and ERD-maps. CNV and ERD could be observed simultaneously over similar brain regions, namely central over the motor cortex, frontal with possible location over the supplementary motor area (SMA) and also covering the parietal region. While the CNV had a interindividually different and wide distribution, the ERD calculated for the upper alpha band mapped focally over the electrode sites C3 and C4 overlaying primary sensorimotor structures, with a contralateral dominance. In contrast to the negativity which is terminated following delivery of the response stimulus, the ERD persisted during the motor reaction showing a similar pattern some hundreds of milliseconds before and after movement onset.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2003

Abnormal CNV in chronic heavy drinkers.

OBJECTIVE: We used the contingent negative variation (CNV), a slow negative shift in the human electroencephalogram, to investigate the effects of heavy chronic alcohol use on frontal lobe function. METHODS: Event-related potentials (ERPs) were recorded from 30 heavy drinkers (HD) and 30 age-, sex-, and education-matched light or non-drinkers (LD), using a classical two-stimulus reaction time (RT) paradigm. Structural magnetic resonance images and neuropsychological tests were also administered. RESULTS: The amplitude of the late CNV was significantly reduced in HD relative to light drinkers. Moreover, diminished CNV amplitudes in HD appear to be closely related to the amount of recent alcohol consumption. There were no significant differences in neuropsychological measures of frontal lobe function and frontal lobe volume between light and HD. However, in HD, reduced late CNV amplitudes were associated with decreased frontal lobe gray matter volume and poor performance on the Trail Making Test B. In LD but not in HD, late CNV amplitude correlated positively with RT, suggesting that the late CNV reflects some aspect of motor and cognitive preparation. CONCLUSIONS: The inverse relationships between frontal lobe gray matter volume, performance on the Trail Making Test B, and late CNV amplitude in HD suggest that the ERP abnormalities observed in the current study may be indices of alcohol-related damage to the frontal lobe. The lack of a significant relationship between CNV amplitude and RT in HD suggests that chronic heavy alcohol use may disrupt response preparation.

Adult↗
PubMed2002

Task-specific expectation is revealed in scalp-recorded slow potentials.

The contingent negative variation (CNV) is known as an electrical manifestation of expectancy, readiness and attention. The purpose of this study was to evaluate whether slow potentials recorded from the human scalp during the expectation to perform different tasks or during the expectation of the second stimulus in the pair demonstrate specificity regarding the type of visual stimuli. Participants were nineteen healthy adults. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Each picture of this pair was a photograph of a familiar face with superimposed abstract dot pattern. One cue directed attention to compare faces and another to compare patterns. EEG was recorded with a 128-channel net. Slow potentials following S1 and S2 presentation (SP1 and SP2) are reported here for Face and Pattern tasks. The duration of each segment of the trial was 1500 ms from the stimulus onset, and here the last 1000 ms was analyzed. Statistical comparisons of amplitudes and current density mapping were performed. Within the same task, SP1-SP2 differences were complex, implying multiple dissimilarities in the processes during the two expectation periods. Slow potentials in SP1 differed between the tasks mostly in the anterior recording sites in 700-1500 ms. These latencies corresponded to the late CNV (or stimulus preceding negativity, SPN) showing task-specificity during SP1. For SP2, the differences were located centrally in 500-900 ms, the period that reflects the superimposition of processes generating the early CNV and the late positive complex. Task-specific differences appeared only in SP1.

Adult↗
PubMed2006

EEG evidence of gender differences in a motor related CNV study.

In the present study gender differences related to the contingent negative variation (CNV) were investigated. A series of two acoustic stimuli was presented to participants across a wide age range. The first stimulus was consistent throughout the experiment whereas the second one was either a high frequency or a low frequency tone. One of them had to be answered by a button press (go condition) the other did not require any response (nogo condition). Between the first and the second tone there was a time period of two seconds in which the CNV appeared as a slow negative potential shift. Within this episode data were analysed with respect to gender differences. Statistical analysis revealed topographical differences between men and women in go conditions for both left and right index finger movements. Differences were found over frontal regions where women showed higher brain activity than men and over temporo-parietal regions where men produced higher brain activity than women. In order to explain the fact that only in "go" conditions significant gender differences occurred we introduce the phenomenon of implicit learning. Due to implicit learning assumed predictions related to S2 might have occurred from time to time. This is so, because a 50% chance for one of two different stimuli to occur leads to reasonable assumed predictions after two or more stimuli of a kind occurring in a series. The present data now provide evidence that if such assumed prediction or expectancy is directed towards an upcoming demand to act then brain activity is subject to gender differences. Further studies providing controlled sequences of "go" conditions versus "nogo" conditions have to be done to prove this idea true.

Acoustic Stimulation↗
PubMed1987

Electrophysiological changes elicited by auditory stimuli given a positive or negative value: a study comparing anhedonic with hedonic subjects.

The present experiment investigates in 'normal' subjects the relationship between personality characteristics (anhedonia versus hedonia) and the influence of the affective value of acoustic stimuli (positive, negative, neutral) on various electrophysiological indices reflecting either tonic activation or phasic arousal (EEG power spectra, contingent negative variation: CNV, heart rate, skin potential responses: SPR) as well as on behavioural indices (reaction time: RT). Eighteen subjects were divided into two groups according to their scores at two self-rating questionnaires, the Chapman's Physical Anhedonia Scale (PAS) and the Beck-Weissman's Dysfunctional Attitude Scale (DAS) that quantifies cognitive distortions presumed to constitute high risk for depression: 9 with high scores at both scales formed the A group (Anhedonic-dysfunctional), 9 with low scores at both scales, the H group (Hedonic-adapted) The electrophysiological indices were recorded during 3 situations: the first one was a classical CNV paradigm with a motor reaction time task in which one of 3 tones of different pitch represented the warning stimulus S1; during the second, conditioning phase, two of these tones were associated with either a success (and reward) or a failure (and punishment) during a memory task in order to make them acquire either a positive or a negative affective value; the third situation consisted in the repeating of the first CNV paradigm in order to test the effect of the positive and the negative stimuli versus the neutral one on RTs and electrophysiological data. Significant between-group differences were found regarding tonic activation as well as phasic arousal indices from the very beginning of the experiment when all stimuli were neutral ones, the anhedonics exhibiting higher activation and arousal than the hedonics at the cortical (increased CNV amplitude, increased power in the beta frequency band), cardiovascular (higher heart rate habituating more slowly) and behavioural (faster RTs) levels. Significant between-group differences were also found concerning reactivity to affective stimuli during the third situation: both the orienting response (but only at the cortical level: early CNV) and the motor preparation processes (late CNV) were in the A group significantly less reactive to affective stimuli (especially to the positive one) than in the H group, in particular concerning the frontal (Fz) data.

Adult↗
PubMed2001

The lateralized readiness potential and response kinetics in response-time tasks.

Previous studies have found that the magnitude of the lateralized readiness potential (LRP) at the time of response initiation is constant across spontaneous variations in response time in both cued and uncued, speeded tasks. Other studies have found that the LRP is also unaffected by instructed changes in peak response force and time to peak force in cued, self-paced tasks, but that the LRP is sensitive to instructed changes in force gain rate in uncued, self-paced tasks. The present study examined the LRP in an uncued, speeded task as a function of response time and several measures of response kinetics. The magnitude of the LRP at the time of electromyographic onset was constant across spontaneous variations in all measures. The peak of the contingent negative variation did vary as a function of peak response force and integrated force to peak, but not response time. These findings support the idea that the LRP in speeded tasks is a selective, on-line index of the preparation associated with using a particular hand, and is not an index of the elements of motor programming that determine subsequent response kinetics.

Adult↗