Topological Re-Organisation of the Brain Connectivity During Olfactory Adaptation - an EEG Functional Connectome Study

Modulating Driver Alertness via Ambient Olfactory Stimulation: A Wearable Electroencephalography Study

“…Then, a sparsity threshold was applied at a ratio of 10% to 40% with increment steps of 1% to remove spurious functional network connections [ 31 ]. Subsequently, each of the four graph metrics under consideration (described in Table 1 ) was estimated within each frequency band by computing the area under curve (AUC) along the whole sparsity range mentioned above [ 32 ].…”

“…Brain metrics, including band power and graph theoretical metrics, were computed from preprocessed data for each trial. Specifically, the short time Fourier transform (STFT) method was used to compute power spectral density (PSD) in five frequency bands power (delta [1][2][3][4], theta [4][5][6][7][8], alpha [8][9][10][11][12], beta [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], and gamma [30][31][32][33][34][35][36][37][38][39][40]). The PSD was then estimated in each frequency band as:…”

“…Figure 4A shows the average RT traces during the [0-30] min segment of the driving task, and Figure 4B shows the average RT traces during the min segment (when fragrance stimuli were delivered) for the two experimental sessions, corresponding to the exposure to the two fragrance stimuli. The two-way repeated measure ANOVA revealed an interaction between fragrance and time (epoch) (p < 0.05) over the min of the driving task and a main effect of fragrance (p < 0.01) over the [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] segment of the driving task. Additionally, the paired-samples t-test indicated that RTs in the experimental session corresponding to the relaxing fragrance were significantly higher than those of the session in which the alerting fragrance was delivered = −3.75, p < 3 × 10 −4 ) over the [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] min segment.…”

“…The two-way repeated measure ANOVA revealed an interaction between fragrance and time (epoch) (p < 0.05) over the min of the driving task and a main effect of fragrance (p < 0.01) over the [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] segment of the driving task. Additionally, the paired-samples t-test indicated that RTs in the experimental session corresponding to the relaxing fragrance were significantly higher than those of the session in which the alerting fragrance was delivered = −3.75, p < 3 × 10 −4 ) over the [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] min segment. There was no difference between the two sessions over the last 15 min of the driving task (the [45-60] segment).…”

“…To investigate the neural underpinnings of the observed behavioral differences in RT, we performed t-tests on each of the EEG metrics (PSD and functional connectivity), across all frequency bands within the [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] min segment. To this goal, the data of each trial for each subject were first averaged to obtain the values for each 5-min epoch, as described in Section 2.5.…”