Libet's experiment is an influential classical study, which does not stop provoking heated debates. However, a full-scale replication has not been carried out to this day. Libet-style studies have usually focused on isolated ideas and concepts and never on the whole experiment in all its complexity. This paper presents detailed methodological description and results of a complex replication study. The methodology follows Libet's directions closely in most cases; when it does not, the differences are described and elaborated. The results replicate Libet's key findings, but substantial differences were found in some of the results' categories, such as the introspective reports or the number of readiness-potentials found. The discussion also addresses some current problems pertaining the methodology of the Libet-style experiments and provides some recommendations based on a detailed process evaluation.
- MeSH
- dospělí MeSH
- elektroencefalografie MeSH
- elektromyografie MeSH
- hmatová percepce fyziologie MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé MeSH
- mladý dospělý MeSH
- pohybová aktivita fyziologie MeSH
- psychomotorický výkon fyziologie MeSH
- uvědomování si fyziologie MeSH
- vědomí fyziologie MeSH
- vnímání času fyziologie MeSH
- zpráva o sobě MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
An infrequent change to an otherwise repetitive sequence of stimuli leads to the generation of mismatch negativity (MMN), even in the absence of attention. This evoked negative response occurs in the scalp-recorded electroencephalogram (EEG) over the temporal and frontal cortices, 100-250 ms after onset of the deviant stimulus. The MMN is used to detect sensory information processing. The aim of our study was to investigate whether MMN can be recorded in the subthalamic nuclei (STN) as evidence of auditory information processing on an unconscious level within this structure. To our knowledge, MMN has never been recorded in the human STN. We recorded intracerebral EEG using a MMN paradigm in five patients with Parkinson's disease (PD) who were implanted with depth electrodes in the subthalamic nuclei (STN). We found far-field MMN when intracerebral contacts were connected to an extracranial reference electrode. In all five PD patients (and nine of ten intracerebral electrodes), we also found near-field MMN-like potentials when intracerebral contacts were referenced to one another, and in some electrodes, we observed phase reversals in these potentials. The mean time-to-peak latency of the intracerebral MMN-like potentials was 214 ± 38 ms (median 219 ms). We reveal MMN-like potentials in bilateral STN. This finding provides evidence that STN receives sensory (auditory) information from other structures. The question for further research is whether STN receives such signals through a previously described hyperdirect pathway between STN and frontal cortex (a known generator of the MMN potential) and if the STN contributes to sensorimotor integration.
- MeSH
- akustická stimulace MeSH
- elektroencefalografie MeSH
- funkční lateralita MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- neuropsychologické testy MeSH
- nucleus subthalamicus patofyziologie MeSH
- Parkinsonova nemoc komplikace patologie MeSH
- reakční čas fyziologie MeSH
- senioři MeSH
- sluchové evokované potenciály fyziologie MeSH
- stupeň závažnosti nemoci MeSH
- tomografy rentgenové počítačové MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Though consisting of early and late components, the evoked potential preceding a voluntary movement (Bereitschaftspotential - BP) is often considered as a unitary phenomenon. By analyzing intracerebrally recorded BP we attempted to demonstrate that the components are electrophysiological correlates of separate operations. The BPs recorded in 42 epilepsy surgery candidates (28 men, 14 women; aged from 18 to 49 years) during self-paced clenching movements of the hand opposite to the explored hemisphere were investigated in the study. Microdeep intracerebral 5 to 15-contact electrodes were used. The averaged curves were calculated from approximately 30 trials in each case. All the records were taken with a binaural reference. The total number of explored brain regions was 235; the event-related premovement potentials were observed in 121 of them. Three types of premovement responses were observed: (i) the BP with both components; (ii) the BP with the early component only; and (iii) the BP with the late component only. The generators of the early one-component BP were demonstrated in two frontal cortical areas (precentral and middle frontal gyri) and in the parietal area known to be involved in action planning and decision making (precuneus). Some structures generating the early one-component BP were activated during movement; the others were without motor responsiveness. The results suggest a separate elaboration of functional task items in some and their integration in other brain structures, and the existence of volitional mechanisms of different hierarchical character.
- MeSH
- časové faktory MeSH
- dospělí MeSH
- elektroencefalografie MeSH
- elektromyografie MeSH
- epilepsie patologie patofyziologie MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mapování mozku MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mozková kůra patofyziologie MeSH
- pohyb fyziologie MeSH
- rozhodování MeSH
- síla ruky fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Evokované potenciály (EP) jsou jednoduchou neinvazivní funkční metodou k vyšetření mnohých neurologických a psychiatrických onemocnění. Event related potentials (ERP) umožňují sledovat některé aspekty kognitivního zpracování informace u člověka. Nejznámější komponentou ERP je vlna P 300, která má nejen široký experimentálni, ale stále větší význam klinický. Parametry této odpovědi závisí zejména na schopnosti a rychlosti zpracování informace subjektem. Změny této vlny jsou pro některá onemocnění typické. Na téma evokovaných potenciálů bylo do současné doby publikováno velké množství studií. Článek se snaží obecně nastínit problematiku zejm. kognitivních evokovaných potenciálů.
Evoked potentials are simple non-invasive methods of functional examination of neurological and psychiatric disorders. ERP (event related potentials) allow monitoring of various aspects of cognitive processing in humans. The most frequently used component of ERP is wave P300; its utilization is not only experimental, but it also has a growing importance in clinical practice. Results depend mainly on two parameters, speed and ability of the subject to process information. Variations of the waves are illness-specific. Numerous studies investigating EP have been published. The aim of the paper is to provide a general overview of EP with special emphasis on cognitive evoked potentials.
- MeSH
- Alzheimerova nemoc diagnóza patofyziologie patologie MeSH
- biomedicínský výzkum MeSH
- elektroencefalografie metody využití MeSH
- evokované potenciály fyziologie MeSH
- financování organizované MeSH
- kognitivní evokované potenciály P300 fyziologie MeSH
- kontingentní negativní variace fyziologie MeSH
- kraniocerebrální traumata diagnóza patofyziologie patologie MeSH
- lidé MeSH
- magnetická rezonanční tomografie metody využití MeSH
- medicína založená na důkazech trendy MeSH
- neuroanatomie metody MeSH
- neurobehaviorální symptomy fyziologie MeSH
- neurofarmakologie metody MeSH
- neurofyziologie metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
- Klíčová slova
- komponenta N400 lidského sluchu,
- MeSH
- dospělí MeSH
- elektroencefalografie metody využití MeSH
- elektromyografie metody využití MeSH
- elektrookulografie * metody využití MeSH
- evokované potenciály fyziologie MeSH
- experimenty na lidech MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé MeSH
- sluchové evokované potenciály * fyziologie MeSH
- somatosenzorické evokované potenciály fyziologie MeSH
- statistika jako téma MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
The objective of this study was to verify hypothesised changes in event related potentials (visual mismatch negativity, vMMN) in 17 subjects dependent on methamphetamine (MAMP) compared to age and gender matched 17 healthy volunteers. We found a significant correlation between vMMN and duration of methamphetamine abuse (Spearman correlation coefficient r=0.54-0.78; P<.05). The positive correlation indicates drop of originally more negative response to deviant stimulus, what may indicate a pre-attentive processing enhancement in the first years of MAMP abuse with its decease later on. Accordingly, post-hoc analysis revealed significantly stronger vMMN in patients with length of MAMP abuse shorter than 5 years than in paired controls. There were no such differences in abusers with the length of abuse longer than 5 years. The results show that the visual processing on the pre-attentional level can be influenced by long-term MAMP abuse, what can be specifically assessed by vMMN.
- MeSH
- akustická stimulace metody MeSH
- časové faktory MeSH
- dospělí MeSH
- elektroencefalografie metody MeSH
- financování organizované MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé MeSH
- pilotní projekty MeSH
- poruchy spojené s užíváním amfetaminu patofyziologie MeSH
- psychofyzika MeSH
- regresní analýza MeSH
- sluchové evokované potenciály fyziologie MeSH
- studie případů a kontrol MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
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.
- MeSH
- dospělí MeSH
- duševní procesy fyziologie MeSH
- elektroencefalografie MeSH
- epilepsie chirurgie patofyziologie MeSH
- financování organizované MeSH
- implantované elektrody MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- mladiství MeSH
- mozková kůra fyziologie MeSH
- podněty MeSH
- pohyb fyziologie MeSH
- somatosenzorické evokované potenciály fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
This study concerns the question of how task modification affects the frequency occurrence of event-related potentials (ERP) inside the active cortical areas. In 13 candidates for epilepsy surgery, 156 sites in the temporal (74), frontal (73), and parietal (9) cortices were recorded by means of depth and subdural electrodes. Four modifications of the somatosensory evoked P3-like potentials were performed; (i) an oddball paradigm with silent counting of target stimuli (P3c); (ii) an oddball paradigm with a hand movement in response to target stimuli (P3m); (iii) an S1-S2 paradigm, ERP in the P300 time window after the S2 stimulus, with silent counting of target stimuli (S2c), and (iv) an S1-S2 paradigm with a hand movement in response to target stimuli (S2m). In comparing the oddball paradigms with the S1-S2 (contingent negative variation, CNV) paradigms, four regions emerge that are significantly linked with the oddball P3; the prefrontal cortex, the cingulate, the amygdalo-hippocampal complex, and the lateral temporal cortex. A prominent role of the cingulate and the fronto-orbital cortex in the cognitive processing of movement was supported when tasks with identical cognitive loads but different required responses were compared. Even relatively simple cognitive tasks activate many cortical regions. The investigated areas were activated in all tests; however, small regions in each field were active or inactive in relation to the nature of the task. The study indicates a variable and task-dependent internal organization of a highly complex and widely distributed system of active cortical areas.
- MeSH
- dospělí MeSH
- duševní procesy fyziologie MeSH
- elektrická stimulace metody MeSH
- elektroencefalografie MeSH
- financování organizované MeSH
- kognice fyziologie MeSH
- kognitivní evokované potenciály P300 fyziologie MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé MeSH
- mapování mozku MeSH
- mladiství MeSH
- mozková kůra fyziologie MeSH
- psychomotorický výkon fyziologie MeSH
- ruka fyziologie MeSH
- vztah dávky záření a odpovědi MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
