Exemplary extract of the task materials used in Experiment 2.

<p>Exemplary extract of the task materials used in Experiment 2.</p

Pearsons' Correlations Coefficients (two-tailed) for the Physiological Measures (Difference in Alpha Power [in μV²/Hz] and Pupil Size [in mm] between Baseline and Test Condition) and the LGVT Reading Comprehension Score and the Total Reading tTme [in minutes] of Experiment 2.

<p>Note.</p><p>⁺ p <. 10,</p><p>* p <. 05,</p><p>*** p <. 001.</p><p>Pearsons' Correlations Coefficients (two-tailed) for the Physiological Measures (Difference in Alpha Power [in μV²/Hz] and Pupil Size [in mm] between Baseline and Test Condition) and the LGVT Reading Comprehension Score and the Total Reading tTme [in minutes] of Experiment 2.</p

Exemplary extract of the task materials used in Experiment 3.

<p>Exemplary extract of the task materials used in Experiment 3.</p

Topoplot of the percentual changes of alpha (8–13 Hz) frequency band power between baseline condition and test condition for Experiment 2.

<p>Percentual frequency band power changes (i.e., the event-related desynchronization/synchronization, ERD/ERS%) were calculated after the formula given in [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130608#pone.0130608.ref042" target="_blank">42</a>].</p

Pupil Dilation and EEG Alpha Frequency Band Power Reveal Load on Executive Functions for Link-Selection Processes during Text Reading

<div><p>Executive working memory functions play a central role in reading comprehension. In the present research we were interested in additional load imposed on executive functions by link-selection processes during computer-based reading. For obtaining process measures, we used a methodology of concurrent electroencephalographic (EEG) and eye-tracking data recording that allowed us to compare epochs of pure text reading with epochs of hyperlink-like selection processes in an online reading situation. Furthermore, this methodology allowed us to directly compare the two physiological load-measures EEG alpha frequency band power and pupil dilation. We observed increased load on executive functions during hyperlink-like selection processes on both measures in terms of decreased alpha frequency band power and increased pupil dilation. Surprisingly however, the two measures did not correlate. Two additional experiments were conducted that excluded potential perceptual, motor, or structural confounds. In sum, EEG alpha frequency band power and pupil dilation both turned out to be sensitive measures for increased load during hyperlink-like selection processes in online text reading.</p></div

Topoplot of the percentual changes of alpha (8–13 Hz) frequency band power between baseline condition and test condition for Experiment 1.

<p>Percentual frequency band power changes (i.e., the event-related desynchronization/synchronization, ERD/ERS%) were calculated after the formula given in [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130608#pone.0130608.ref042" target="_blank">42</a>].</p

Mean pupil dilation of Experiment 3.

<p>Note. black error bars indicate +1 standard error of the mean.</p

Mean alpha (8–13 Hz) frequency band power at electrode Pz and mean pupil dilation of Experiment 2.

<p>Note. *** indicate p <. 001, black error bars indicate +1 standard error of the mean.</p

Cross-task and cross-participant classification of cognitive load in an emergency simulation game

Assessment of cognitive load is a major step towards adaptive interfaces. However, non-invasive assessment is rather subjective as well as task specific and generalizes poorly, mainly due to methodological limitations. Additionally, it heavily relies on performance data like game scores or test results. In this study, we present an eye-tracking approach that circumvents these shortcomings and allows for effective generalizing across participants and tasks. First, we established classifiers for predicting cognitive load individually for a typical working memory task (n-back), which we then applied to an emergency simulation game by considering the similar ones and weighting their predictions. Standardization steps helped achieve high levels of cross-task and cross-participant classification accuracy between 63.78% and 67.25% for the distinction between easy and hard levels of the emergency simulation game. These very promising results could pave the way for novel adaptive computer-human interaction across domains and particularly for gaming and learning environments

Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity

<div><p>Background</p><p>The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene <i>SLC6A4</i> and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence.</p><p>Methods</p><p>A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (V_max) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet V_max.</p><p>Results</p><p>The present study demonstrates that increases in platelet V_max significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within <i>SLC6A4</i>. Furthermore, functional connectivity analyses indicate that platelet V_max is related to global DMN activation and not intrinsic DMN connectivity.</p><p>Conclusion</p><p>This study provides evidence that platelet V_max predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal V_max coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation.</p></div