Gamma band oscillations in parietooccipital areas during performance of a sensorimotor integration task: a qEEG coherence study

Noninvasive modulation of predictive coding in humans: causal evidence for frequency-specific temporal dynamics

Increasing evidence indicates that the brain predicts sensory input based on past experiences, importantly constraining how we experience the world. Despite a growing interest on this framework, known as predictive coding, most of such approaches to multiple psychological domains continue to be theoretical or primarily provide correlational evidence. We here explored the neural basis of predictive processing using noninvasive brain stimulation and provide causal evidence of frequency-specific modulations in humans. Participants received 20 Hz (associated with top-down/predictions), 50 Hz (associated with bottom-up/prediction errors), or sham transcranial alternating current stimulation on the left dorsolateral prefrontal cortex while performing a social perception task in which facial expression predictions were induced and subsequently confirmed or violated. Left prefrontal 20 Hz stimulation reinforced stereotypical predictions. In contrast, 50 Hz and sham stimulation failed to yield any significant behavioral effects. Moreover, the frequency-specific effect observed was further supported by electroencephalography data, which showed a boost of brain activity at the stimulated frequency band. These observations provide causal evidence for how predictive processing may be enabled in the human brain, setting up a needed framework to understand how it may be disrupted across brain-related conditions and potentially restored through noninvasive methods.

How high level of anxiety in Panic Disorder can interfere in working memory? A computer simulation and electrophysiological investigation

Panic disorder (PD) is characterized by repeated and unexpected attacks of intense anxiety, which are not restricted to a determined situation or circumstance. The coherence function has been used to investigate the communication among brain structures through the quantitative EEG (qEEG). The objective of this study is to analyze if there is a difference in frontoparietal gamma coherence (GC) between panic disorder patients (PDP) and healthy controls (HC) during the Visual oddball paradigm; and verify if high levels of anxiety (produced by a computer simulation) affect PDP's working memory. Nine PDP (9 female with average age of 48.8, SD: 11.16) and ten HC (1 male and 9 female with average age of 38.2, SD: 13.69) were enrolled in this study. The subjects performed the visual oddball paradigm simultaneously to the EEG record before and after the presentation of computer simulation (CS). A two-way ANOVA was applied to analyze the factors Group and the Moment for each pair of electrodes separately, and another one to analyze the reaction time variable. We verified a F3-P3 GC increased after the CS movie, demonstrating the left hemisphere participation during the anxiety processing. The greater GC in HC observed in the frontal and parietal areas (P3-Pz, F4-F8 and Fp2-F4) points to the participation of these areas with the expected behavior. The greater GC in PDP for F7-F3 and F4-P4 pairs of electrodes assumes that it produces a prejudicial "noise" during information processing, and can be associated to interference on the communication between frontal and parietal areas. This "noise" during information processing is related to PD symptoms, which should be better known in order to develop effective treatment strategies.

Comparative analysis electroencephalographic of alpha, Beta and gamma bands of a healthy individual and one with hemiparesis

[Purpose] The study analyzed the electroencephalographic (EEG) data of the central cortical areas, during execution of the motor gestures of feeding, activation of the system of mirror neurons, and imagery between a right hemiparetic volunteer (RHV) and a healthy volunteer (HV). [Subjects and Methods] The volunteers’ EEG data were recorded with their eyes open for 4 minutes while they performed five experimental tasks. [Results] The alpha band, absolute power value of HV was lower than that of RHV. In the beta band, during the practice condition, there was an increase in the magnitude of the absolute power value of HV at T3, possibly because T3 is representative of secondary motor areas that work with cortical neurons related to planning and organizing sequence of movements performed by the hands. The gamma band is related to the state of preparation for movement and memory. The results of this study indicate that there was increased activation of the gamma frequency band of HV. [Conclusion] The findings of this study have revealed the changes in pattern characteristics of each band which may be associated with the brain injury of the hemiparetic patient.