Using intracerebral EEG recordings in a large cohort of human subjects, we investigate the time course of neural cross-talk during a simple cognitive task. Our results show that human brain dynamics undergo a characteristic sequence of synchronization patterns across different frequency bands following a visual oddball stimulus. In particular, an initial global reorganization in the delta and theta bands (2-8 Hz) is followed by gamma (20-95 Hz) and then beta band (12-20 Hz) synchrony.

• MeSH
• Adult MeSH
• Electroencephalography MeSH
• Cognition physiology   MeSH
• Cortical Synchronization physiology   MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Brain physiology   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

The objective is to study the involvement of the posterior medial cortex (PMC) in encoding and retrieval by visual and auditory memory processing. Intracerebral recordings were studied in two epilepsy-surgery candidates with depth electrodes implanted in the retrosplenial cingulate, precuneus, cuneus, lingual gyrus and hippocampus. We recorded the event-related potentials (ERP) evoked by visual and auditory memory encoding-retrieval tasks. In the hippocampus, ERP were elicited in the encoding and retrieval phases in the two modalities. In the PMC, ERP were recorded in both the encoding and the retrieval visual tasks; in the auditory modality, they were recorded in the retrieval task, but not in the encoding task. In conclusion, the PMC is modality dependent in memory processing. ERP is elicited by memory retrieval, but it is not elicited by auditory encoding memory processing in the PMC. The PMC appears to be involved not only in higher-order top-down cognitive activities but also in more basic, rather than bottom-up activities.

• MeSH
• Acoustic Stimulation MeSH
• Adult MeSH
• Electroencephalography methods   MeSH
• Epilepsy physiopathology   MeSH
• Electrodes, Implanted MeSH
• Humans MeSH
• Brain physiology   MeSH
• Memory physiology   MeSH
• Signal Processing, Computer-Assisted MeSH
• Evoked Potentials, Auditory physiology   MeSH
• Photic Stimulation MeSH
• Evoked Potentials, Visual physiology   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

What is the neural substrate of our capability to properly react to changes in the environment? It can be hypothesized that the anterior cingulate cortex (ACC) manages repetitive stimuli in routine conditions and alerts the dorsolateral prefrontal cortex (PFC) when stimulation unexpectedly changes. To provide evidence in favor of this hypothesis, intracerebral stereoelectroencephalographic (SEEG) data were recorded from the anterior cingulate and dorsolateral PFC of eight epileptic patients in a standard visual oddball task during presurgical monitoring. Two types of stimuli (200 ms duration) such as the letters O (frequent stimuli; 80% of probability) and X (rare stimuli) were presented in random order, with an interstimulus interval between 2 and 5 s. Subjects had to mentally count the rare (target) stimuli and to press a button with their dominant hand as quickly and accurately as possible. EEG frequency bands of interest were theta (4-8 Hz), alpha (8-12 Hz), beta (14-30 Hz), and gamma (30-45 Hz). The directionality of the information flux within the EEG rhythms was indexed by a directed transfer function (DTF). The results showed that compared with the frequent stimuli, the target stimuli induced a statistically significant increase of DTF values from the anterior cingulate to the dorsolateral PFC at the theta rhythms (P < 0.01). These results provide support to the hypothesis that ACC directly or indirectly affects the oscillatory activity of dorsolateral PFC by a selective frequency code under typical oddball conditions.

• MeSH
• Action Potentials physiology   MeSH
• Biological Clocks physiology   MeSH
• Gyrus Cinguli anatomy & histology   physiology   MeSH
• Adult MeSH
• Mental Processes physiology   MeSH
• Electroencephalography methods   MeSH
• Evoked Potentials physiology   MeSH
• Data Interpretation, Statistical MeSH
• Cognition physiology   MeSH
• Humans MeSH
• Brain Mapping MeSH
• Young Adult MeSH
• Neural Pathways anatomy & histology   physiology   MeSH
• Neurons physiology   MeSH
• Neuropsychological Tests MeSH
• Signal Processing, Computer-Assisted MeSH
• Prefrontal Cortex anatomy & histology   physiology   MeSH
• Photic Stimulation MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

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.

• MeSH
• Acoustic Stimulation MeSH
• Basal Ganglia physiology   MeSH
• Frontal Lobe physiology   MeSH
• Gyrus Cinguli physiology   MeSH
• Adult MeSH
• Evoked Potentials physiology   MeSH
• Cognition physiology   MeSH
• Contingent Negative Variation physiology   MeSH
• Humans MeSH
• Brain Mapping MeSH
• Adolescent MeSH
• Motor Cortex physiology   MeSH
• Neural Pathways physiology   MeSH
• Movement physiology   MeSH
• Prefrontal Cortex physiology   MeSH
• Putamen physiology   MeSH
• Reaction Time physiology   MeSH
• Auditory Perception physiology   MeSH
• Evoked Potentials, Auditory physiology   MeSH
• Visual Perception physiology   MeSH
• Evoked Potentials, Visual physiology   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH