Emitted and evoked P300 potentials and variation in stimulus probability.
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Acoustic Stimulation↗
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[Cognitive evoked potentials in patients with schizophrenia].
OBJECTIVE: To investigate the features of cognitive evoked potentials (CEPs) in schizophrenics and the changes of CEPs between the duration of episode and remission. METHODS: The present study was made with stimuli of auditory, visual, and somatosensory modalities. CEPs were recorded from 31 episodical schizophrenics and 25 of them were retested when their clinical symtoms rempitted. RESULTS: The episodical patients showed significantly longer A latency (P < 0.05) and PINV latency (P < 0.01), and smaller A-S2' area (P < 0.01). Shorter latency was associated with P2 of auditory evoked potential, visual evoked potential and somatosensory evoked potential (P < 0.05), P1 of AEP, N2 of VEP, and N1 of SEP (P < 0.05). Longer latency was associated with P3 of AEP (P < 0.05). Diminished amplitude was associated with N1-P2 of AEP and N1-P2 of VEP, P2 of VEP, and P2-N2 of SEP (P < 0.05). The follow-up study revealed that when the psychiatric symptoms remitted, the waveform of CEPs became more steady; amplitude B of CNV, N1-P2 of VEP and P2-N2 of SEP were increased (P < 0.05); the amplitude P2 of AEP and VEP, and P1 of AEP were increased into the normal range. CONCLUSION: The variations of CEPs are the state marker of schizophrenia.
Adolescent↗
[Structure of phenotypic variability in readiness potential in 6-7 year-old children].
This report is a part of a larger project, the major purpose of which is a longitudinal study of developmental changes in genetic control of variation in Bereitshaft potentials (BP). 15 pairs of MZ and 15 pairs of DZ twins aged 6-7 years participated in the BP study. 2 second epochs of EEC time-locked to the movement were digitized off-line at 500 Hz (DAS-16G "Metrabyte"), for 1500 msec, prior to and 5000 msec after movement. A complex BP waveform with the positive components was discovered in young children. We fitted four basic models to the twin data for each of the BP in F3, F4, C3, C4. Since the models (VA, EW) in F3, F4, C3 and (EB, EW) in C4 fit very well and cannot be improved markedly by adding the most important alternative parameters, we conclude that variation of BP of F3, F4, C3 is best explained by a very simple genetic model, and variation of BP of C4 is best explained by a simple environmental model.
Child↗
Controllability of an aversive stimulus in depressed patients and health controls: a study using slow brain potentials.
Slow brain potentials (CNV and PINV) were recorded from 18 patients with primary depression and 18 health controls under three experimental conditions. A short tone (S1) indicated the occurrence of an aversive tone stimulus (S2) which could not be terminated by a motor reaction in Condition 1 (C1) but was terminated in C2. In C3 the reaction time (RT) had to be faster than the shortest mean RT from C1 and C2 in order to stop the aversive stimulus. For both groups the RT decreased from C1 to C2 to C3 and the CNV increased from C2 to C3. CNV and RT did not differ between the groups in either condition. In C1 and C3 (uncontrollability and restricted control over the aversive stimulus) patients developed a marked PINV which was not observed in the control group. In view of other investigations which found a PINV in normal subjects in situations of sudden, unexpected uncontrollability, the present results demonstrate that depressed patients are more sensitive to levels and variation of uncontrollability than healthy subjects. A possible relationship to Seligman's concept of helplessness is discussed.
Arousal↗
Effects of information processing demands on slow negative shift latencies and N100 amplitude in selective and divided attention.
The influence of information processing demands on auditory event-related potentials (ERPs) in selective and divided attention was examined by varying the stimulation rate and target difficulty in a two-channel discrimination task. Subjects were required to detect targets in either one or both ears (channels) in a series of tones presented randomly to both ears. The amplitude of the N100 component (latency 80-140 msec) of the ERP to all stimuli in an attended channel was greater if attention was focused on that channel that if it was directed to the opposite channel. N100 amplitude was also reduced in divided attention compared to focused attention. In general, these effects were obtained only if the stimulation rate was high and/or targets were difficult to detect. However, these effects of attention modulated an underlying slow negative shift (SNS) rather than N100 directly. The onset and peak latencies of the SNS were strongly dependent on the processing demands of the task. The results show that the temporal relationship of the SNS to the N100 component is the principal factor responsible for variations in the effects of attention on the ERP with changes in information processing demands. The relationship between these ERP components and resource allocation theories of attention is discussed.
Adolescent↗
[The significance of slow brain potentials for the estimation of activation processes in activities at the video-screen model workplace].
Numerous studies have shown that the slow potentials registered in the EEG allow conclusions on changes in activation processes preceding different activities. The Bp which has so far been analysed preferably as motoric phenomenon, is in the following used to furnish evidence of activation processes preceding mental performance at a visual display terminal. The analysis reveals the relationships between the Bp and mental load, mental performance, and a varying dynamic activation. From that, conclusions can be drawn already in the phase of preparing different information processing activities on variations in central-nervous activation and most likely even on the readiness to perform and the reliability of actions.
Action Potentials↗
Differential effects of the stimulus sequence on CNV and P300.
During the presentation of stimulus sequences in oddball paradigms, participants tend to implicitly evaluate the conditional probability of target occurrence. It is not sure, however, if subjective estimation of conditional probabilities modulates target expectancy and target processing in the same manner. In the present experiment, the amplitudes of CNV and P300 were studied separately to compare preparatory and decision mechanisms and their sensitivity to variations in target probability. Amplitudes of both components were measured at different positions in the stimulus sequence, which modulates target probability as a function of distance from the preceding target. Results showed shorter RTs with increased probability of target occurrence (that is, with longer distance to the previous target). CNV amplitude was low when target probability was zero and maximal when the occurrence of a target was possible, regardless of its probability. Conversely, a gradual increase with augmenting probability was observed for P300 amplitude. Thus, preparatory activity as reflected by the CNV showed an all or nothing response to variations in probability, whereas action closure mechanisms, indexed by P300 components, were found to be more sensitive to subtle differences in stimulus expectancy.
Adult↗
Topographic CNV activity mapping, presenile mild primary cognitive decline and Alzheimer-type dementia.
The CNV complex evoked with a standard paradigm (S1-2 sec-S2-motor response) and reaction time (RT) to the imperative signal (S2) were recorded and measured in 12 patients with initial presenile idiopathic cognitive decline (PICD), 12 with presenile Alzheimer-type dementia (PAD) and 10 healthy age-matched controls. Significant group differences were obtained for measures of some CNV components, particularly of the late pre-S2 CNV. No significant CNV activity, very prolonged RTs and sometimes characteristic post-imperative negative variations (PINV) were observed in the majority of patients with PAD. These results suggest that similar CNV complex and RT changes to those observed in our patients may constitute a valuable clue in the study of pathophysiological brain functioning in the early stages of presenile idiopathic mental deterioration.
Aged↗
Examining task-dependencies of different attentional processes as reflected in the P3a and reorienting negativity components of the human event-related brain potential.
Unexpected changes in task-irrelevant auditory stimuli are capable to distract processing of task-relevant visual information. This effect is accompanied by the elicitation of event-related potential (ERP) components associated with attentional orientation, i.e. P3a and reorienting negativity (RON). In the present study we varied the demands of a visual task in order to test whether the RON component -- as an index of attentional reorientation after distraction -- is confined to a semantic task requiring working memory. In two ERP experiments we applied an auditory-visual distraction paradigm in which subjects were instructed to discriminate visual stimuli preceded by a task-irrelevant sound, this being either a standard tone (600 Hz, 88%) or a deviant tone (660 Hz, 12%). The visual stimuli were numbers which had to be judged on basis of a semantic (odd or even) or physical feature (either size or colour). As expected, deviance related ERP components namely the mismatch negativity (MMN), P3a, and RON were elicited. Importantly, the RON was affected by the variation of the task: within the semantic task an early RON and within the physical task a late RON was obtained. These results suggest that the RON component reflects two functionally distinct processes of attentional allocation after distraction: refocusing on task-relevant information on the working memory level, and general reorientation of attention, e.g. preparation for the upcoming task.
Acoustic Stimulation↗
Electrophysiological correlates of change detection.
To identify electrophysiological correlates of change detection, event-related brain potentials (ERPs) were recorded while participants monitored displays containing four faces in order to detect a face identity change across successive displays. Successful change detection was mirrored by an N2pc component at posterior electrodes contralateral to the side of a change, suggesting close links between conscious change detection and attention. ERPs on undetected-change trials differed from detected-change and no-change trials. We suggest that short-latency ERP differences between these trial types reflect trial-by-trial fluctuations in advance task preparation, whereas differences in the P3 time range are due to variations in the duration of perceptual and decision-related processing. Overall, these findings demonstrate that ERPs are a useful tool for dissociating processes underlying change blindness and change detection.
Adult↗
Operant control of EEG and event-related and slow brain potentials.
Research on operant control of brain potentials is reviewed. From single-unit firing and spontaneous EEG activity to event-related potentials such as sensory and pain evoked potentials, and slow potential shifts, most of the aspects of electrical brain activity have been investigated. Results produced by conditioning of spontaneous EEG oscillations (alpha and theta) dampened the early enthusiasm: e.g., no increase above baseline levels could be achieved and no reliable behavioral effects became manifest. Evidence accumulates, however, that operant conditioning of the sensorimotor rhythm (12-15 Hz) may lead to successful self-regulation and that epileptic patients may profit from the training. First steps in the conditioning of brainstem, as well as pain evoked potentials suggest that self-regulation of EPs can be achieved by adequate biofeedback procedures. If some of the observed behavioral effects prove to be stable, the therapeutic usefulness seems to be within reach. A comparable progress has been achieved for the operant control of slow potentials (DC-shifts across seconds). Biofeedback procedures have been used successfully as a scientific tool to achieve systematic variations on a psychological level and to record psychological covariations. This method may provide insights into the behavioral meaning of electrical brain activity.
Biofeedback, Psychology↗
Motivational slow negative potential shift (CNV) related to thalamotomy.
The alteration of cortical electrical activity induced by imperative stimulation following warning stimulation, contigent negative variation (CNV), and psychological changes following thalamotomy for relief of intractable pain (CM) and tremor (VL) are studied, since CNV has a close relationship with the degree of psychological activity. Ventrolateral thalamotomy does not have any effect on the amplitude of cortical CNV, but the ventromedioposterior part of the centre median has a generating action of CNV in itself and it has facilitatory effects upon cortical CNV. According to these results, the effective mechanism of centre median thalamotomy for relief of intractable pain is caused by suppression of attention and expectancy for exogenous stimuli following lesions of the centre median.
Contingent Negative Variation↗
[The psychophysiological aspects of treating obesity with Izolipan].
20 patients with obesity were examined. Their weight was increased as compared with ideal values by 30-140%. The patients were characterized by anxious or depressive disturbances (Spilberger's and Beck tests) and alterations of alimentary behaviour in form of prevalence of emotional and external alimentary behaviour (EMAB and EAB, respectively). The study of cognitive negative variations (CNV) revealed the decrease of late wave's area, which correlated reversely with levels of anxiety, depression and EMAB expression. The Isolipan administration (15 mg, 2 times/daily during 3 months) together with hypocaloric diet resulted in average weight loss equal to 12.3 kg in the whole group. These changes correlated well with normalization of both alimentary behaviour (in the form of decrease of EMAB and EAB indices) and emotional state, and increase of decreased late CNV with disappearance of pathological psycho-physiological correlations between CNV and emotional state.
Acoustic Stimulation↗
Does sleep quality affect involuntary attention switching system?
We studied the relationship between sleep quality and quantity and subsequently recorded automatically evoked event-related potential (ERP) responses. In previous studies decrement of attentional processing has been associated with changes in sleep. Sleep is shown to associate also with ERPs elicited by unattended sound stream, however, there is no consensus on these effects. A recent study suggested that the early anterior P3a to novel stimuli in attended stream is attenuated and the late parietal P3a is strengthened by total sleep deprivation. We carried out 72-h consecutive actigraphy measurements in a naturalistic setting to collect information about variation in sleep duration, sleep onset latency, sleep efficiency, and percentage of sleep. MMN and P3a deflections to infrequent changes in sound duration and pitch in unattended sound stream were obtained in a separate recording session from the same subjects when they were awake. No significant correlations were found between sleep and MMN parameters, indicating that MMN is resistant to normal variation in sleep. However, P3a to both pitch and duration changes correlated positively with sleep onset latency, and P3a to duration changes correlated negatively with sleep efficiency and percentage of sleep. The correlation was higher in the posterior scalp areas. Our results suggest that the involuntary attention switching system, reflected by the P3a is sensitized as a function of decreased sleep quality.
Acoustic Stimulation↗
Frontocortical activity in children with comorbidity of tic disorder and attention-deficit hyperactivity disorder.
Comorbidity of tic disorder (TD) and attention-deficit hyperactivity disorder (ADHD) in children is common but not fully understood. Thus we investigated the effect of TD and ADHD on the amplitude of the postimperative negative variation (PINV) in children with combined tic + hyperactivity symptoms (TD + HA). PINV was chosen as an indicator of frontal lobe functioning that is closely related to self-regulation of behavior. PINVs of four groups of children (healthy controls, pure TD, pure ADHD, and combined TD + HA; total number 43) were elicited in an auditory warned reaction task in three conditions (control = CC, loss-of-control = LoCC, and lack-of-control = LaCC) at midfrontal (Fz) and midcentral (Cz) leads of the scalp. Effects of TD and ADHD were revealed only in the noncontrol conditions, being independent in the LaCC, but interactive in the LoCC. Thus, the additive model of psychopathological classification concerning the comorbidity of TD and ADHD was only partially supported by the observed pattern of psychophysiological results.
Attention↗
Late evoked responses to acoustic stimuli in relation to age.
Late hearing potentials (contigent negative variations; CNV) were studied in 66 subjects of different ages: 15 children, 26 adults and 25 elderly people (extreme ages of 4 and 100 years). Particular care was taken in selection of phonetic material suitable for each age. No CNVs were recorded in children under the age of 5 years; only 2 of the children examined presented late responses for all the phonetic lists. In adults, such cases rose to 5(19.2%), while another 16(61.5%) presented responses for some or a good part of the lists in question. Only in 9 elderly people were typical CNVs observed (36%). The discussion outlines the reasons for the low percentages of late responses obtained in children and point out that in some elderly subject accustomed to psychic and motor activities typical CNV are present.
Acoustic Stimulation↗
Altered fronto-central PINV topography and the primary negative syndrome in schizophrenia.
Postimperative negative variation (PINV) was recorded during a warned reaction time paradigm in 16 chronic DSM-IIIR schizophrenics in remission. Clinical symptoms were assessed by BPRS, SANS and the anhedonia scale of the Chapman Questionnaire. Ten healthy controls were studied in the same manner. Over the fronto-central area we found a significantly elevated PINV amplitude with an altered topographical distribution in the patient group. The difference values 'PINV Cz-PINV Fz' were correlated negatively with primary negative symptoms of schizophrenia.
Adult↗
Postimperative negative variation and skin conductance response in chronic DSM-III-R schizophrenia.
The hypothesis was tested that there are relationships between schizophrenic negative or deficit symptoms, the skin conductance nonresponding and an elevated amplitude of the postimperative negative variation (PINV). These variables were recorded in 16 chronic schizophrenics and 10 healthy controls. Clinical symptoms were assessed by the Brief Psychiatric Rating Scale, Scale for the Assessment of Negative Symptoms, Frankfurt Complaint Questionnaire 3 and Chapman Questionnaire. In the patient group we found a significantly elevated PINV at Fz. Surprisingly, only one patient was a skin conductance nonresponder. PINV amplitude at Fz and the number of skin conductance responses to habituation were not correlated with negative or deficit symptoms inclding anhedonia. The hypothesis thus had to be rejected.
Adult↗