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Granger causality analysis reveals distinct spatio-temporal connectivity patterns in motor and perceptual visuo-spatial working memory.

Protopapa F, Siettos CI, Evdokimidis I, Smyrnis N - Front Comput Neurosci (2014)

Bottom Line: We employed spectral Granger causality analysis on a full set of 56 electroencephalographic recordings acquired during the execution of either a 2D movement pointing or a perceptual (yes/no) change detection task with memory and non-memory conditions.On the basis of network characteristics across frequency bands, we provide evidence for the full dissociation of the corresponding cognitive processes.Our results favor the hypothesis which considers spatial working memory as a by-product of specific mental processes that engages common brain areas under different network organizations.

View Article: PubMed Central - PubMed

Affiliation: School of Applied Mathematics and Physical Sciences, National Technical University of Athens Athens, Greece.

ABSTRACT
We employed spectral Granger causality analysis on a full set of 56 electroencephalographic recordings acquired during the execution of either a 2D movement pointing or a perceptual (yes/no) change detection task with memory and non-memory conditions. On the basis of network characteristics across frequency bands, we provide evidence for the full dissociation of the corresponding cognitive processes. Movement-memory trial types exhibited higher degree nodes during the first 2 s of the delay period, mainly at central, left frontal and right-parietal areas. Change detection-memory trial types resulted in a three-peak temporal pattern of the total degree with higher degree nodes emerging mainly at central, right frontal, and occipital areas. Functional connectivity networks resulting from non-memory trial types were characterized by more sparse structures for both tasks. The movement-memory trial types encompassed an apparent coarse flow from frontal to parietal areas while the opposite flow from occipital, parietal to central and frontal areas was evident for the change detection-memory trial types. The differences among tasks and conditions were more profound in α (8-12 Hz) and β (12-30 Hz) and less in γ (30-45 Hz) band. Our results favor the hypothesis which considers spatial working memory as a by-product of specific mental processes that engages common brain areas under different network organizations.

No MeSH data available.


Related in: MedlinePlus

Schematic of the experimental procedure. (A) Movement-memory task (M-M), (B) Movement-non memory task (M-NM), (C) Change detection-memory task (CD-M), (D) Change detection-non memory task (CD-NM).
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Figure 1: Schematic of the experimental procedure. (A) Movement-memory task (M-M), (B) Movement-non memory task (M-NM), (C) Change detection-memory task (CD-M), (D) Change detection-non memory task (CD-NM).

Mentions: Four types of trials were performed by ten right-handed volunteers (seven men and three women) between the ages of 29 and 44 (mean age of 35) in a randomized order as described in a previous study (Smyrnis et al., 2014). All participants had no history of major medical or psychiatric illness and had normal or corrected-to-normal vision. They were fully informed about the experimental procedure and gave written informed consent. The study protocol was approved by the Aeginition Hospital Ethics committee and conformed to the 2013 WMA Declaration of Helsinki. For the sake of completeness of the presentation, we also describe it here briefly (see also Figure 1). At the beginning of each trial, a small circle was presented at the center of the monitor. The color of the circle was either blue indicating that the trial would be completed by making a pointing movement (movement task), or red indicating that the trial would be completed by pressing one of two buttons giving a yes/no response (change detection task). At the end of the baseline period which lasted randomly between 1500 and 2500 ms, a target was presented at one of 36 (equally distributed around 360° of an invisible circle) peripheral locations. After 250 ms (duration of target presentation) the background monitor color changed again either masking the peripheral target (memory condition) or allowing the target to remain visible (non-memory condition). After a delay period that varied randomly between 3500 and 4500 ms, the central circle disappeared; this served as a “go” signal for initiating a response.


Granger causality analysis reveals distinct spatio-temporal connectivity patterns in motor and perceptual visuo-spatial working memory.

Protopapa F, Siettos CI, Evdokimidis I, Smyrnis N - Front Comput Neurosci (2014)

Schematic of the experimental procedure. (A) Movement-memory task (M-M), (B) Movement-non memory task (M-NM), (C) Change detection-memory task (CD-M), (D) Change detection-non memory task (CD-NM).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230052&req=5

Figure 1: Schematic of the experimental procedure. (A) Movement-memory task (M-M), (B) Movement-non memory task (M-NM), (C) Change detection-memory task (CD-M), (D) Change detection-non memory task (CD-NM).
Mentions: Four types of trials were performed by ten right-handed volunteers (seven men and three women) between the ages of 29 and 44 (mean age of 35) in a randomized order as described in a previous study (Smyrnis et al., 2014). All participants had no history of major medical or psychiatric illness and had normal or corrected-to-normal vision. They were fully informed about the experimental procedure and gave written informed consent. The study protocol was approved by the Aeginition Hospital Ethics committee and conformed to the 2013 WMA Declaration of Helsinki. For the sake of completeness of the presentation, we also describe it here briefly (see also Figure 1). At the beginning of each trial, a small circle was presented at the center of the monitor. The color of the circle was either blue indicating that the trial would be completed by making a pointing movement (movement task), or red indicating that the trial would be completed by pressing one of two buttons giving a yes/no response (change detection task). At the end of the baseline period which lasted randomly between 1500 and 2500 ms, a target was presented at one of 36 (equally distributed around 360° of an invisible circle) peripheral locations. After 250 ms (duration of target presentation) the background monitor color changed again either masking the peripheral target (memory condition) or allowing the target to remain visible (non-memory condition). After a delay period that varied randomly between 3500 and 4500 ms, the central circle disappeared; this served as a “go” signal for initiating a response.

Bottom Line: We employed spectral Granger causality analysis on a full set of 56 electroencephalographic recordings acquired during the execution of either a 2D movement pointing or a perceptual (yes/no) change detection task with memory and non-memory conditions.On the basis of network characteristics across frequency bands, we provide evidence for the full dissociation of the corresponding cognitive processes.Our results favor the hypothesis which considers spatial working memory as a by-product of specific mental processes that engages common brain areas under different network organizations.

View Article: PubMed Central - PubMed

Affiliation: School of Applied Mathematics and Physical Sciences, National Technical University of Athens Athens, Greece.

ABSTRACT
We employed spectral Granger causality analysis on a full set of 56 electroencephalographic recordings acquired during the execution of either a 2D movement pointing or a perceptual (yes/no) change detection task with memory and non-memory conditions. On the basis of network characteristics across frequency bands, we provide evidence for the full dissociation of the corresponding cognitive processes. Movement-memory trial types exhibited higher degree nodes during the first 2 s of the delay period, mainly at central, left frontal and right-parietal areas. Change detection-memory trial types resulted in a three-peak temporal pattern of the total degree with higher degree nodes emerging mainly at central, right frontal, and occipital areas. Functional connectivity networks resulting from non-memory trial types were characterized by more sparse structures for both tasks. The movement-memory trial types encompassed an apparent coarse flow from frontal to parietal areas while the opposite flow from occipital, parietal to central and frontal areas was evident for the change detection-memory trial types. The differences among tasks and conditions were more profound in α (8-12 Hz) and β (12-30 Hz) and less in γ (30-45 Hz) band. Our results favor the hypothesis which considers spatial working memory as a by-product of specific mental processes that engages common brain areas under different network organizations.

No MeSH data available.


Related in: MedlinePlus