Coupling Between Brain Structures During Visual and Auditory Working Memory Tasks

2019 ◽  
Vol 29 (03) ◽  
pp. 1850046 ◽  
Author(s):  
Maciej Kaminski ◽  
Aneta Brzezicka ◽  
Jan Kaminski ◽  
Katarzyna J. Blinowska
Keyword(s):  
Working Memory ◽  
Transfer Function ◽  
Memory Task ◽  
Brain Structures ◽  
Metabolic Energy ◽  
Auditory Task ◽  
Frequency Range ◽  
Directed Transfer Function ◽  
Eeg Activity ◽  
Short Time

Transmission of EEG activity during a visual and auditory version of the working memory task based on the paradigm of linear syllogism was investigated. Our aim was to find possible similarities and differences in the synchronization patterns between brain structures during the same mental activity performed on different modality stimuli. The EEG activity transmission was evaluated by means of full frequency Directed Transfer Function (ffDTF) and short-time Directed Transfer Function (SDTF). SDTF provided information on dynamical propagation of EEG activity. The assortative mixing approach was applied to quantify coupling between regions of interest encompassing frontal, central and two posterior modules. The results showed similar schemes of coupling for both modalities with stronger coupling within the regions of interests than between them, which is concordant with the theories concerning efficient wiring and metabolic energy saving. The patterns of transmission showed main sources of activity in the anterior and posterior regions communicating intermittently in a broad frequency range. The differences between the patterns of transmission between the visual and auditory versions of working memory tasks were subtle and involved bigger propagation from the posterior electrodes towards the frontal ones during the visual task as well as from the temporal sites to the frontal ones during the auditory task.

scholarly journals Application of directed transfer function and network formalism for the assessment of functional connectivity in working memory task

2013 ◽  
Vol 371 (1997) ◽  
pp. 20110614 ◽  
Author(s):  
Katarzyna J. Blinowska ◽  
Maciej Kamiński ◽  
Aneta Brzezicka ◽  
Jan Kamiński
Keyword(s):  
Working Memory ◽  
Functional Connectivity ◽  
Transfer Function ◽  
Brain Networks ◽  
Memory Task ◽  
Metabolic Energy ◽  
Modular Structure ◽  
Directed Transfer Function ◽  
Clear Cut ◽  
Strength Of Interaction

The dynamic pattern of functional connectivity during a working memory task was investigated by means of the short-time directed transfer function. A clear-cut picture of transmissions was observed with the main centres of propagation located in the frontal and parietal regions, in agreement with imaging studies and neurophysiological hypotheses concerning the mechanisms of working memory. The study of the time evolution revealed that most of the time short-range interactions prevailed, whereas the communication between the main centres of activity occurred more sparsely and changed dynamically in time. The patterns of connectivity were quantified by means of a network formalism based on assortative mixing—an approach novel in the field of brain networks study. By means of application of the above method, we have demonstrated the existence of a modular structure of brain networks. The strength of interaction inside the modules was higher than between modules. The obtained results are compatible with theories concerning metabolic energy saving and efficient wiring in the brain, which showed that preferred organization includes modular structure with dense connectivity inside the modules and more sparse connections between the modules. The presented detailed temporal and spatial patterns of propagation are in line with the neurophysiological hypotheses concerning the role of gamma and theta activity in information processing during a working memory task.

Determination of information flow direction among brain structures by a modified directed transfer function (dDTF) method

2003 ◽  
Vol 125 (1-2) ◽  
pp. 195-207 ◽  
Author(s):  
Anna Korzeniewska ◽  
Małgorzata Mańczak ◽  
Maciej Kamiński ◽  
Katarzyna J. Blinowska ◽  
Stefan Kasicki
Keyword(s):  
Transfer Function ◽  
Information Flow ◽  
Flow Direction ◽  
Brain Structures ◽  
Directed Transfer Function

scholarly journals Hippocampal theta phases organize the reactivation of large-scale electrophysiological representations during goal-directed navigation

2019 ◽  
Vol 5 (7) ◽  
pp. eaav8192 ◽  
Author(s):  
Lukas Kunz ◽  
Liang Wang ◽  
Daniel Lachner-Piza ◽  
Hui Zhang ◽  
Armin Brandt ◽  
...  
Keyword(s):  
Working Memory ◽  
Large Scale ◽  
Memory Performance ◽  
Memory Task ◽  
Neural Mechanisms ◽  
Object Location Memory ◽  
Theta Phase ◽  
Hippocampal Theta ◽  
Intracranial Electroencephalography ◽  
Short Time

Humans are adept in simultaneously following multiple goals, but the neural mechanisms for maintaining specific goals and distinguishing them from other goals are incompletely understood. For short time scales, working memory studies suggest that multiple mental contents are maintained by theta-coupled reactivation, but evidence for similar mechanisms during complex behaviors such as goal-directed navigation is scarce. We examined intracranial electroencephalography recordings of epilepsy patients performing an object-location memory task in a virtual environment. We report that large-scale electrophysiological representations of objects that cue for specific goal locations are dynamically reactivated during goal-directed navigation. Reactivation of different cue representations occurred at stimulus-specific hippocampal theta phases. Locking to more distinct theta phases predicted better memory performance, identifying hippocampal theta phase coding as a mechanism for separating competing goals. Our findings suggest shared neural mechanisms between working memory and goal-directed navigation and provide new insights into the functions of the hippocampal theta rhythm.

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

Articulatory Suppression Increases Proactive and Semantic Interference in a Working Memory Task

2008 ◽  
Author(s):  
Alexandra S. Atkins ◽  
Marc G. Berman ◽  
John Jonides ◽  
Patricia A. Reuterlorenz
Keyword(s):  
Working Memory ◽  
Articulatory Suppression ◽  
Memory Task ◽  
Semantic Interference
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