**3.3. Gender-related asymmetry during facial processing by** *f***TCD**

REGIONS × STIMULATIONS × ARTERIES, F (4,24) = 4.76, MSE = 25392, p < 0.01. An analysis of covariance (ANCOVA) with repeated measures was applied to demonstrate that the difference found during color stimulation persists even when the difference due to baseline condition was partialled out. In men, there was significant increase in MFV produced by luminance, hence WAVELENGTH-encoding activity could only be adjudged after partialling out the changes under Dark and Light conditions as changing covariates. Conversely, in women, there was no change in MFV associated with luminance, and hence only baseline Dark

**Figure 6.** A-D). Shows the plots of spectral density estimates for dark, light and color stimuli (blue, yellow) for the RMCA in men (Figure 6A), for the LMCA in men (Figure 6B); for the RMCA in women (Figure 6C) and LMCA in women

(Figure 6D). (Source modified from: Njemanze PC. Exp Transl Stroke Med 2010, 2:21-27.).

In men, in the RMCA, at C-peaks, there was a tendency for ENERGY-encoding, F(1,5) = 5.95, MSE = 10315, p = 0.058. However, at S-peaks, there was a significant main effect of WAVE‐ LENGTH-encoding, F(1,5) = 9.98, MSE = 1016.8, p < 0.05. This may suggest that, there was WAVELENGTH-differencing in the right hemisphere in men. There was no luminance effect in the RMCA territory, p = NS. However, in the LMCA, there was an orthogonal LUMINANCE effect, F(1,5) = 6.27, MSE = 6834.6, p < 0.05. Figure 6A shows that the RMCA S-peaks were 'topologically' separated, achromatic from chromatic peaks, and between the latter, short

condition was used as a covariate.

154 Advancements and Breakthroughs in Ultrasound Imaging

The LI for men is displayed in Figure 7A, and for women in Figure 7B, respectively.

**Figure 7.** A-B). Shows the box and whiskers plot of mean/SE /1.96\*SE of LI during object (Paradigm 1) and facial (Paradigms 2-5) stimulation in men (Figure 7A) and women (Figure 7B).

Overall, men were right lateralized for facial Paradigms 2-5 as well as non-face object Paradigm 1. On the other hand, women were left lateralized for facial Paradigms 2-5, but right lateralized for object Paradigm 1. However, on exclusion of outliers, women showed no lateralization with zero LI value or bilateral activation during object processing. In men, at baseline MFV in dark condition did not differ between RMCA and LMCA. Paradigms 1–5 induced significant variation in MBFV in the RMCA (p < 0.01) and LMCA (p < 0.001), that resulted in right lateralization for all tasks. There was a marginal difference between Paradigm 2 and Paradigm 3 (p = 0.06), due to more pronounced activation in the LMCA (p < 0.01) than RMCA (p = 0.053) (Figure 7A) during Paradigm 3. Overall, tasks were right lateralized (p < 0.001), showing stimulus-specific effect in lateralization. The LI for women is displayed in Figure 7B. At baseline MFV in dark condition was higher in LMCA than R-MCA, and Paradigms 1–5 induced significantly greater attenuation of MFV in the RMCA (p < 0.05) than in the L-MCA (p < 0.001). As a result, there was left lateralization for all Paradigms 1-5 (Figure 7B). There was no difference between Paradigm 2 and Paradigm 3. In other words, in women, stimulus-specific effects did not yield lateralization of MFV. Given the observed marginal tendencies for changes between Paradigms 1-3, the *f*TCDS analysis was carried out for dark and Paradigms 1-3 effects.

marginal tendency for luminance effect. In men, in the LMCA at C-peaks, there was a main effect of STIMULATION, F(3, 18) = 4.4, MSE = 39947, p = 0.05. Planned contrast revealed a facial processing strategy effect, p = 0.05, (Figure 8B). However, at S-peaks there was no main effect of STIMULATION. In women, in the RMCA at C-peaks, there was a main effect of STIMU‐ LATION, F(3, 18) = 4.2, MSE = 38441.9, p = 0.05. Planned contrast revealed a luminance effect, p = 0.05 (Figure 8C). Similarly, at the S-peaks there was a marginal tendency for luminance effect. In women, in the LMCA at C-peaks, there was a main effect of STIMULATION, F(3, 18) = 3.2, MSE = 2791.4, p = 0.05. Planned contrast revealed a facial processing strategy effect, p =

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The cardiovascular measures that could cause confounding effects were assessed using oneway analysis of variance (ANOVA). In men the heart rate during Paradigm 1 (71.9±10.6 bpm), Paradigm 2 (69.6±11 bpm), and Paradigm 3 (70.5±5 bpm) did not differ from resting baseline (67.5±9 bpm), (p = 0.05). Similarly, in women the heart rate during Paradigm 1 (76.9±9.8 bpm), Paradigm 2 (78.9±12 bpm), and Paradigm 3 (79.3±13.8 bpm) did not differ from resting baseline (76.9±9.6 bpm), (p = 0.05). In men the respiratory rate during Paradigm 1 (17.3±3.5 per minute), Paradigm 2 (19.9±5.7 per minute), and Paradigm 3 (16.9±3.7 per minute) did not differ from resting baseline (17.9±2.5 per minute), (p=0.05). Similarly, in women the respiratory rate during Paradigm 1 (19±4.5 per minute), Paradigm 2 (21±5 per minute), and Paradigm 3 (21±6 per minute) did not differ from resting baseline (19.3±6.4 per minute), (p > 0.05). The overall mean heart rate was 74 bpm and respiratory rate was 19 per minute. There was no significant difference between pre-test and post-test blood pressure, (p > 0.05). Similarly, there were no significant differences between the stimuli for heart rate, respiratory rate, and anxiety scores (p > 0.05). In other words, there were no changes in cardiovascular parameters and anxiety scores during the study. In post-test debriefings, participants described their initial condition as ''blank'', unaware of subtle emotional state, as they tried to focus attention on the imagery spot within the dark visual field. Women described the paradigms in greater detail than men. For example, on first prompt for description, most men described Paradigm 1 simply as a draught board or chess board, while most women described it as alternating black and white squares within a cube. For execution of Paradigm 3, both men and women reported sorting one part of the face at a time into place before proceeding to the next part, in other words, all followed a step-by-step approach. All rated themselves as not being anxious, and assessed

0.05 (Figure 8D). However, at S-peaks there was no main effect of STIMULATION.

themselves as having good performance, with no difficulty with task execution.

Overall, the gender-related differences could be summarized as follows: (1) in men, wave‐ length-differencing activity was enhanced at high luminance effect, conversely, in women, frequency-differencing activity was enhanced at low luminance effect. (2) In men, luminance

**4.1. Gender-related asymmetry during color processing**

**3.5. Confounding effects**

**4. Discussion**

#### **3.4. Gender-related asymmetry during facial processing by** *f***TCDS**

The spectral density plots for each artery during all study conditions in Figures 8 A-D, in men (Figure 8 A-B) and women (Figure 8 C-D), respectively.

**Figure 8.** A-D). Shows the plots of spectral density estimates for dark, object (Paradigm 1) and facial (Paradigms 2-3) stimulation for the RMCA in men (Figure 8A), for the LMCA in men (Figure 8B); for the RMCA in women (Figure 8C) and LMCA in women (Figure 8D). (Source modified from: Njemanze PC. Laterality 2007, 12:31-49.).

In general, for all stimulations in both men and women there were three peaks designated as **F**-, **C**-, and **S**-peaks, representing the fundamental, cortical, and subcortical peaks, which occurred at regular frequency intervals of 0.125, 0.25, and 0.375, respectively. The spectral density peaks were analyzed for each gender separately to examine the effect of dark and stimulations at **C**- and **S**-peaks for the RMCA and LMCA, respectively. A one-way ANOVA with repeated measures for all four levels of STIMULATION (Dark, Paradigms 1-3) was used. This was followed by planned contrasts. In men, in the RMCA at C-peaks, there was a main effect of STIMULATION, F(3, 18) =4.2, MSE= 16804.3, p=0.05. Planned contrast revealed a category-specific face effect, p = 0.05, (Figure 8A). However, at the S-peaks there was only a marginal tendency for luminance effect. In men, in the LMCA at C-peaks, there was a main effect of STIMULATION, F(3, 18) = 4.4, MSE = 39947, p = 0.05. Planned contrast revealed a facial processing strategy effect, p = 0.05, (Figure 8B). However, at S-peaks there was no main effect of STIMULATION. In women, in the RMCA at C-peaks, there was a main effect of STIMU‐ LATION, F(3, 18) = 4.2, MSE = 38441.9, p = 0.05. Planned contrast revealed a luminance effect, p = 0.05 (Figure 8C). Similarly, at the S-peaks there was a marginal tendency for luminance effect. In women, in the LMCA at C-peaks, there was a main effect of STIMULATION, F(3, 18) = 3.2, MSE = 2791.4, p = 0.05. Planned contrast revealed a facial processing strategy effect, p = 0.05 (Figure 8D). However, at S-peaks there was no main effect of STIMULATION.
