cognitive task
Research Papers
The Coordinated Allocation of Resource (CAR) Electrophysiological Patterns of Recalling Names of Faces in Children, Adolescents and Adults and the Central Processing Unit (CPU) of the Brain
The quantitative EEG (QEEG) has proven to be an important methodology in the understanding of brain functioning. The Coordinated Allocation of Resource (CAR) model maintains that cognitive effectiveness depends on the employment of a specific set of resources for specific cognitive tasks, which overlap in some situations. The model employs the flashlight metaphor in understanding the coherence and phase relations between locations. The metaphor asserts that each location can function as a flashlight that sends out a “beam” to the other locations within a frequency. The “beam” can involve all the other locations or be a mini-flashlight that involves only selected locations. The task of recalling names of faces was examined in the context of the CAR model. The developmental changes that occur during the encoding of names of faces include increases in diffusely located communication connections involving theta (4–8 Hz) and alpha (8–13 Hz), increases in the relative power values of the beta variables (13–64 Hz), peak frequency of beta1 (13–32 Hz) and alpha, decreases in communication patterns involving the beta2 (32–64 Hz) and delta (0–4 Hz) frequencies as well as decreasing values of variables involving the lower frequencies (delta, theta), relative power values of alpha and magnitudes of alpha, beta2 and peak amplitudes of beta2.The face-name task is both a verbal and visual task as the participant is hearing the name while he looks at the photograph. Variables that relate to success during the encoding task involve diffuse increases in flashlight activity from F7 and T3 across all frequencies to and between central locations. The QEEG variables that relate to immediate and delayed recall success involve flashlights from T3 across 4 frequencies, F7 involving 3 frequencies and the appearance of a heuristic “central processing unit” involving frontal (F3, Fz, F4), central (C3, Cz, C4) and posterior (P3, Pz, P4) locations.
View Full Paper →Effects of SMR and Theta/Beta Neurofeedback on Reaction Times, Spatial Abilities, and Creativity
Neurofeedback training (NFT) has been demonstrated to be a useful, inexpensive, nonpharmacological tool in the treatment of attention deficit hyperactivity disorder and epilepsy in humans. Different neurofeedback training protocols have been associated with positive effects on performance in sports, creativity, memory, and simple reaction time tasks. During NFT, individuals receive visual or acoustic feedback of their brain oscillations, which are recorded by electroencephalogram (EEG). Through operant conditioning that employs this feedback, the individuals subsequently may be able to modulate the respective oscillations. The most widely used training protocols focus on either the enhancement of the sensorimotor rhythm (SMR; 12-15Hz) or modulation of the theta/beta ratio (TBR; theta: 4.5-7.5 Hz, beta: 17-21 Hz). We investigated whether healthy individuals are able to learn, within 30 NFT sessions, how to modulate either the SMR (n=13) or the TBR (n=14), and whether such modulation can lead to an enhancement in different cognitive or creative tasks. A control group (n=14) that received NFT with daily changing frequency bands and instructions was included for comparison. Although neither the TBR group nor the control group was able to modulate the EEG in the trained frequency bands, the SMR group was successful in doing so. In addition, only the SMR group was able to attain significantly better results in simple and choice reaction time tasks and a spatial rotation task after training as compared to the two other groups. No effects of NFT were found for the other attention-related tasks or for creative tasks. A series of 30 SMR training sessions can increase the ability to increase SMR amplitudes and therefore may have a future application in settings where the cultivation of fast reactions and good visuospatial abilities are relevant (e.g., in sports).
View Full Paper →Long-term stability and consistency of EEG event-related (de-)synchronization across different cognitive tasks
Objective We examined whether task-related band power changes (event-related desynchronization/synchronization; ERD/ERS) that have been linked to individual differences in cognitive ability demonstrate satisfying temporal stability and cross-situational consistency. Methods Multi-channel EEG recordings from 29 adults, assessed at three different occasions over 2 years were examined. Between-session correlations and consistency coefficients (Cronbach's alpha) across the three experiments were evaluated for both, spectral power features of the resting EEG and ERD/ERS estimates while the participants performed some cognitive task (i.e. different elementary cognitive tasks that put comparable demands on the participants). Results ERD/ERS values, while subjects performed a cognitive task, demonstrated satisfactory stability and consistency (i.e. >0.7), whereby the degree of consistency varied as a function of frequency band and brain region. Highest consistency was found for the 8–10Hz ERD in parieto-occipital recording sites (i.e. >0.9). In resting EEG, mean alpha (gravity) frequency was the most stable EEG feature. Conclusions The present data suggest that ERD/ERS phenomena in different narrow frequency bands are rather stable over time and across different situations. The relatively high reproducibility of ERD/ERS promotes the usefulness of this measure in assessing individual differences of physiological activation patterns accompanying cognitive performance. Significance This study addresses the issue of reproducibility of EEG in general and ERD/ERS experiments in particular, which is a prerequisite for both basic research and clinical studies.
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