Bereitschaftspotential preceding eyelid blinks in Parkinson's disease / Potencial de Bereitschafts precedendo o piscamento ocular na doença de Parkinson

ABSTRACT The Bereitschaftspotential (BP) is a negative wave observed in EEG retrograde averaging, preceding a motor act. The objective was to study the BP preceding voluntary eyelid blinks in Parkinson's disease (PD) patients during off and on phases of levodopa. Methods Ten PD patients in stages 1 and 2 of the Hoehn & Yahr classification were compared to 18 healthy controls. Artifact-free EEG segments of two seconds preceding the onset of the blink potential were averaged and analyzed, and the statistical significance of the measured amplitudes were evaluated by analysis of variance models. Results The presence of a BP in the PD patients was demonstrated. The mean amplitudes at 0 ms were respectively 0.6 µV and 3.3 µV for the BP patients and the normal controls, respectively. Conclusions The BP amplitudes were significantly smaller in PD patients than normal participants. The amplitudes of the BP were not modified by levodopa.

RESUMO O Potencial de Bereitschafts (PB) é uma onda negativa observada retrogradamente no EEG precedendo um ato motor. Objetivo Estudar o PB precedendo o piscamento palpebral voluntário em pacientes com doença de Parkinson (DP) durante as fases off e on da levodopa. Foram comparados dez pacientes com DP nos estágios 1 e 2 de Hoehn & Yahr com 18 controles saudáveis. Os segmentos de EEG livres de artefatos 2 segundos antes do início do potencial foram calculados e analisados e a significância estatística das amplitudes foi medida por modelos de análise de variância. Resultados A presença de PB nos pacientes com DP foi demonstrada. As amplitudes médias a 0 ms foram respectivamente 0,6 μV e 3,3 μV para os pacientes com DP e controles respectivamente. Conclusões As amplitudes do PB foram significativamente menores nos pacientes com DP do que controles. As amplitudes do PB não foram modificadas pela levodopa.

Contingent negative variation: a brainwave associated with expectation / 生物医学工程学杂志

The present study used the experimental patterns of Go/No Go and no motion contingent negative variation (CNV) task into the research in order to study whether the CNV can express the implication of expectation. Through comparing the CNV under different conditions, the data collected from experiment showed that the key to evoked CNV was close to the warning signal and command signal. Whether the command signal was related to the task would impact on the amplitude of the CNV. This characteristics responses to the subjects' expectation. On this basis, CNV can be used as the electrophysiological index for the reflection of expected value in the conditions of this experiment.

Contingent Negative Variation Is Associated with Cognitive Dysfunction and Secondary Progressive Disease Course in Multiple Sclerosis

BACKGROUND AND PURPOSE: The relationship between contingent negative variation (CNV), which is an event-related potential, and cognition in multiple sclerosis (MS) has not been examined previously. The primary objective of the present study was thus to determine the association between CNV and cognition in a sample of MS patients. METHODS: The subjects of this study comprised 66 MS patients [50 with relapsing-remitting MS (RRMS) and 16 with secondary progressive MS (SPMS)] and 40 matched healthy volunteers. A neuropsychological battery was administered to all of the subjects; CNV recordings were made from the Cz, Fz, and Pz electrodes, and the amplitude and area under the curve (AUC) were measured at each electrode. RESULTS: RRMS patients exhibited CNVs with lower amplitudes and smaller AUCs than the controls at Pz. SPMS patients exhibited CNVs with lower amplitudes and smaller AUCs than the controls, and CNVs with a smaller amplitude than the RRMS patients at both Cz and Pz. After correcting for multiple comparisons, a lower CNV amplitude at Pz was significantly associated with worse performance on measures of speed of information processing, verbal fluency, verbal learning, and verbal recall. CONCLUSIONS: CNV may serve as a marker for disease progression and cognitive dysfunction in MS. Further studies with larger samples and wider electrode coverage are required to fully assess the value of CNV in these areas.

The Contingent Negative Variation in Remitted Paediatric Bipolar Patients: No Evidence of Abnormality

Although the Contingent Negative Variation (CNV) paradigm has been useful in schizophrenia, limited research involving such paradigm in subjects with Bipolar Disorder (BD) has produced contradictory findings. To the best of our knowledge, no study has investigated CNV in Paediatric Bipolar Disorder (PBD) subjects. Thirty remitted PBD patients and thirty matched healthy control group subjects participated in the study. No significant between group main effect could be found for either CNV latency or amplitude. We propose that CNV is unlikely to be a true endophenotype of BD. However, absence of CNV finding during euthymic phase in BD may help us in advancing our understanding of BD and such finding may, in fact, have some specificity with regard to differentiating BD from schizophrenia.

Contribuição do Mismatch Negativity na avaliação cognitiva de indivíduos portadores de esclerose múltipla / Mismatch Negativity contribution in Multiple Sclerosis patients

O Mismatch Negativity (MMN) é um potencial evocado auditivo endógeno, gerado por mudanças no processo de discriminação que ocorrem no córtex auditivo que avalia a memória sensorial auditiva. OBJETIVOS: Avaliar se, quando presente, o MMN pode ser utilizado como um índice funcional do córtex auditivo supratemporal e correlacionar com comprometimento cognitivo, avaliado pelo Teste Auditivo Compassado de Adição Seriada (PASAT). MATERIAL E MÉTODOS: Um grupo controle e outro com diagnóstico definido de EM foram submetidos ao registro do MMN com estímulos auditivos com variação de duração e de freqüência. O grupo de EM foi submetido ao PASAT. As latências e as amplitudes negativas do MMN foram comparadas entre os grupos. Os escores do PASAT foram correlacionados com a presença ou ausência do MMN nos dois protocolos de estimulação auditiva. RESULTADOS: O MMN esteve presente em 60 por cento dos indivíduos no grupo de EM no protocolo de estimulação auditiva com variação de duração, e em 45 por cento no protocolo de estimulação auditiva com variação de freqüência. Encontrou-se uma correlação estatisticamente significante entre a ausência da onda do MMN com a presença de comprometimento cognitivo avaliado pelo PASAT. CONCLUSÕES: A ausência do MMN se correlaciona com comprometimento cognitivo avaliado pelo PASAT.

Mismatch Negativity is a functional index of the supratemporal auditory cortex. AIM: The aim of the present study on Mismatch Negativity (MMN) in multiple sclerosis (MS) patients was to evaluate if the MMN can be correlated with cognitive deficits assessed by the Paced Auditory Addition Task - PASAT. METHOD: a clinical study in forty females and 20 males separated in two groups: control individuals and those with a definite diagnosis of MS underwent a duration and frequncy MMN. The MMN latencies and negative amplitudes obtained from the MS group were compared to the ones from the control group. The scores from the Paced Auditory Addition Task were correlated either with the presence or the absence of MMN. RESULTS: MMN was found in 60 percent of the individuals with multiple sclerosis within the auditory stimulation protocol with varied durations, and in 45 percent within the auditory stimulation protocol with frequency variations. There were no statistically significant differences in latencies and amplitudes when compared to controls. We found a statistically significant correlation for the lack of MMN wave together with cognitive disorder asserted by the PASAT. CONCLUSIONS: The MMN correlated to the cognitive deficit assessed by the PASAT.

Contingent Negative Variation of Pre- and Post-Hemodialysis in Patient with End Stage Renal Disease

BACKGROUND: The contingent negative variation (CNV) reflects neuronal activities related to sensorimotor integration and motor planning or execution and is probably originated from the frontal-subcortical circuit. The aim of this study is to investigate the neurophysiologic changes in uremia and the effect of hemodialysis to them by utilizing the CNV test. METHODS: Fifteen right-handed healthy subjects and 12 patients with end stage renal disease (ESRD) were studied. CNV was recorded from Fz, Cz, and Pz referenced to linked ear lobes by using an S1 (click)-S2 (flashes)-key press paradigm. The amplitude of initial CNV (iCNV) was calculated as the average amplitude of 550~750 msec after S1. The amplitude of late CNV (lCNV) was calculated as the average amplitude between 200 msec before S1 and S2. The test was repeated for the patients group at the time of pre- and post-hemodialysis. Neuropsychological measurements, the trail making test (TMT) and mini-mental state score (MMSE), were conducted at the time of each test. RESULTS: Both the mean amplitudes of iCNV and lCNV at the vertex (Cz) were significantly lower in the patient group than those in the control group (p<0.05). The MMSE score and TMT were also significantly different between the patient and control group (p<0.05). There was no significant correlation between the values of neuropsychological tests and the parameters of CNV. Both iCNV and lCNV were not significantly different between the pre- and post-dialysis test. CONCLUSIONS: It appears that CNV negativity in uremia reflects dysfunctions in the frontal-subcortical circuit. In addition, hemodialysis seems to have no significant effect on it in patients with ESRD.

Bereitschaftspotential in tic disorders: a preliminary observation.

Sensory phenomena in tic disorders such as Tourette's syndrome are known but are substantiated by only a handful of studies. In this preliminary report, we studied premonitory urge, a type of sensory phenomenon in three patients of tic disorders. Bereitschaftspotential, a movement-related cognitive potential indicative of motor preparation, was assessed in these patients. As bereitschaftspotential was observed in all our cases prior to occurrence of tics, it is speculated that tics are not entirely involuntary but are quasi-volitional in nature. Bereitschaftspotential may thus represent a neurophysiological marker of premonitory urge in tic disorders. Implications of exploring the voluntary nature of tics are discussed.

Task related changes in contingent negative variation (CNV) response of endogenous evoked potentials.

Contingent negative variation (CNV) is a slow negative cortical potential shift, which occurs during a warned foreperiod reaction time paradigm. Most studies of evoked potentials have concentrated on components occurring during the first 300 msec, although there are important and recordable aspects of signal processing occurring well beyond 300 msec e.g. late negative slow wave. CNV has proven sensitive to a number of psychological variables, none of which can yet be singled out as a definitive or exclusive correlate. Changes are expected if measured after a rigorous mental exercise. CNV was measured in 20 normal male subjects aged between 18 and 20 years. CNV was recorded twice in each subject before and after the administration of a mental task. The auditory mental task comprised repeating in reverse order string of random digits read out to the subject at a uniform speed of 1 per second. The visual mental task comprised reading laterally inverted type written text. Each subject had to undergo 2 sessions in separate sittings. The latency and amplitude of waves N1, P3, orientation (O), expectancy (E), CNV, reaction time (RT) were recorded. These values recorded before and after the task were compared statistically using student's unpaired t-test. The significant latencies recorded before and after the auditory task were, N1: 88.00 +/- 11.96 and 100.00 +/- 21.52 msec, P3: 289.00 +/- 54.85 and 299.00 +/- 52.91 msec, reaction time (RT): 102 +/- 17.05 msec and 123 +/- 17.5 msec, and in case of visual task, N1: 88 +/- 13.16 msec and 99.00 +/- 16.51 msec, reaction time (RT): 107 +/- 11.74 msec and 127 +/- 13.42 msec respectively. All other CNV wave latencies and amplitude changes were insignificant. Hence task effects sensory perception as reflected by increased latency of the long latency response N1 and the cortical integrative processes resulting in increased reaction time.

Averaged evoked potentials: event related potentials (ERPs) and their applications.

Endogenous potentials are evoked responses that occur independent of the stimulus evoking them. They are related to different aspects of information processing. Two types of event related potentials (ERPs) are recorded, the P300 wave and contingent negative variation (CNV). The P300 wave is the most frequently studied factor in various clinical diseases and also for neurological research. Different tasks, paradigms can be used of which the oddball paradigm, consisting of target and non-target stimuli and their variations is most popular. The effect on P300 of physiological factors like age, IQ, pregnancy, exercise and others along with the clinical application in various neurophysiological and psychiatric disorders are discussed. This review deals with various aspects of (ERPs), their methodology with a broad view of the scope and clinical horizon as regard their application in neurophysiological research.

Olfactory Functional MRI Using Echo Planar Imaging Methods / 대한이비인후과학회지

BACKGROUND: Various olfactory tests have already been proposed in order to clinically assess the olfactory function, for example, UPSIT, T & T olfactometer, CCCRC test, GITU, IV olfaction test. At recent, electro-olfactogram(EOG), olfactorhinometry, olfactory evoked potential, contingent negative variation was tried as the objective olfactory test. OBJECTIVES: We use the functional imaging of MRI which affords the potential for exploring regional pathophysiologic change in living brain as an olfactory function test. MATERIALS AND METHODS: Functional MRI scans of the brain were performed on 5 healthy subjects and 3 patients with olfactory dysfunction. 2 of the patients were diagnosed Parkinson's disease and the other one had basal skull fracture. Then, all subjects were performed CCCRC test. RESULT: 6 of 8 subjects showed significant region of activation in olfactory bulb and tract. Additional region of activation were also observed in amygdala and parahippocampus. Average activation ratio was 3.42+/-2.37%. CONCLUSION: These studies indicate that functional MRI have many limitations but it may be used to evaluate olfactory dysfunction and predict prognosis.

Contingent negative variation response in chronic pain patients.

The present study assesses central processing of subjective appraisal, expectancy, orientation and reaction time as indexed by Contingent Negative variation (CNV) response in chronic pain patients. Waves N1, P3 and CNV were recorded during a CNV paradigm in a simple reaction time task with a constant interstimulus interval (ISI) of 1 sec. CNV was measured from CZ x FZ in controls and chronic pain patients suffering from cervical spondylosis and low backache due to sciatica. Duration of pain was 5 to 10 years and intensity varied from moderate to severe as adjudged by Visual Analogue Scale. CNV experiment consisted of 32 trials of S1 and S2 motor response sequence. Each trial consisted of warning sound click stimulus (S1) followed by the imperative stimulus in the form of flashes (S2). S2 could be terminated by the subject quickly by pressing a response button with the dominant hand. Cursors were hand set to score the latencies for N1 and P3 potentials to S1, maximal CNV amplitude was scored as the largest negative ongoing potential immediately prior to S2 onset. Similarly Reaction Time (RT), Orientation (O) and Expectancy (E) wave amplitudes and latencies were recorded. There was a significant increase in P3 latency, RT in chronic pain patients, indicating that there is a blunting of cognitive functions and increase in reaction time in patients suffering from chronic pain. These patients also take more time to orient to CNV paradigm.

Los potenciales relacionados con los eventos: CNV y PINV en sujetos normales y disléxicos / Potencials related to events: CNV and PINV in normal and dyslexic subjects

La variación contingente negativa (CNV) es una onda cerebral que ha sido asociada con los procesos de expectancia, atención, anticipación y preparación de una respuesta. La duración o resolución de esta onda es conocida como la variación negativa postimperativa (PINV). En la presente investigación se estudiaron las características dela onda PINV en una población de niños con rendimiento escolar adecuado y niños con transtornos en el proceso de lectura. Con base en el rendimiento, en una batería psicoeducativa previamente administrada a 120 niños mexicanos, se seleccionaron 9 sujetos con rendimiento escolar adecuado y sin antecedentes patológicos y 9 sujetos cuya ejecución en la batería psicoeducativa se encontraba dos desviaciones estándar por debajo de las normas estandarizadas. Se utilizaron registros monopolares referidos a lóbulos auriculares cortocircuitados. Siguiendo el Sistema 10-20 internacional se colocaron electrodos en F3, Cz, P3 y 01. Debido a los resultados estadísticos, se observó que dos grupos de sujetos eran significativamente diferentes en la amplitud de la onda PINV en la zona parietal izquierda. Se discute la participación que puede tener esta zona en este transtorno y se consideran factores tales como espectancia, atención y procesamiento de la información en las diferentes encontradas

La investigacion fisiologica y la psiquiatria clinica. Estudios de aproximacion. / Physiological research and clinical psychiatry. Approach studies

Se describe parcialmente una de las lineas de investigacion desarrollada en la Unidad de Psicofisiologia de la Facultad de Medicina de la Universidad de Chile. Despues de precisar el concepto de fisiologia empleado en estos estudios y de senalar la posicion del concepto de comportamiento entendido como funcion del organismo total -se describe su relacion con el trabajo clinico en psiquiatria, particularmente en lo que respecta a la descripcion de la conducta y al establecimiento de categorias diagnosticas de amplia valides consensual. Estudios sobre la variacion contingente negativa (CNV) durante tareas de tiempo de reaccion son utilizados como ejemplo de estrategia metodica en psicofisiologia clinica

Psicofisiología cerebral: La variación contingente negativa y su aplicación en psicología y psicopatología / Cerebral psychophysiology: the contingent negative variation and its application on psychology and psychopathology

Se describe los fenómenos fisiológicos y constructos psicológicosa subyacentes a la Variación Contingente Negativa (CNV), un potencial cerebral lento ligado a eventos mentales. En base a la teoría del "arousal" -atención, se interpretan y discuten resultados obtenido en nuestro laboratorio que demuestran la posibilidad de usar este indicador electrocortical para definir fisiológicamente rasgos psicológicos