## 3 Results  
The time course of BOLD, ADC, and \(\gamma\) within a specific volume of interest (VOI) were compared separately for each subject. VOIs were defined by thresholding activation maps at \(Z_{score}\geq 10\) for BOLD and \(Z_{score}\geq 3\) for ADC and \(\gamma\) maps. The response as a function of the scan number (1 scan number = 1.4 s) for a representative subject and the average among all the subjects are displayed in Figure 2a,b, respectively. Please note that the absolute value of ADC, \(\gamma\), and BOLD variation between a resting and activated state is displayed. In agreement with [PERSON] [23], the ADC time course showed a feeble decrease at stimulus onset, and overall, the BOLD and ADC expansion time courses were approximately similar in shape (Figure 2a,b, upper row). Conversely, the \(\gamma\) time course showed a feeble-medium increase at stimulus onset. In Figure 2a,b (upper row), the BOLD and \(\gamma\) expansion time courses were compared to each other, highlighting a better matching than that observed between ADC and BOLD. Moreover, the \(\gamma\) response is higher (but not significantly when the results of all the subjects are considered) than that of ADC. In all subjects, the ADC and \(\gamma\) activation maps (displayed in Figure 2c), directly calculated from the raw diffusion-sensitized MRI signals, clearly showed activation of primary as well as secondary visual areas, such as the visual motion area MT/V5, which is typically activated by flickering stimuli [61]. The spatial extent of the activation was more  
Figure 2: Time courses of the \(\gamma\) parameter and BOLD fMRI signals (lower row), Normal Gaussian diffusion quantified by ADC (obtained with b = 2000 s/mm\({}^{2}\) and b = 80 s/mm\({}^{2}\)), and BOLD fMRI signals (upper row) for a representative subject (**a**); time courses of the \(\gamma\) and BOLD fMRI signals (lower row), ADC (obtained with b = 2000 s/mm\({}^{2}\) and b = 80 s/mm\({}^{2}\)), and BOLD fMRI signals (upper row) for the averaged signal among all the investigated subjects (**b**). The gray swathes/dashed lines indicate stimulation and rest blocks (time expressed in scan units; 1 scan = 1.4 s). The error bars in (**a**) represent the standard deviation of the response across the corresponding eight epochs. Please note that the absolute value of ADC, \(\gamma\), and BOLD variation between the resting and activated state is displayed. Indeed, during activation, ADC decreases, whereas the \(\gamma\) and BOLD signals increase. BOLD fMRI, Normal Gaussian diffusion (ADC) fMRI, and \(\gamma\) activation maps for a representative subject (**c**). Voxels were classified as significantly activated at uncorrected \(p\)-values < 0.005. The maps displayed in (**c**) show that ADC and \(\gamma\) maps provide improved localization of activation areas (visual areas, V1, V2, V3, V4, V5) compared to BOLD localization. restricted to the primary visual region for \(\gamma\) and DW fMRI than BOLD, in agreement with [PERSON] et al. [62] and other authors [28; 34]. The interpretation of these results is that \(\gamma\) could be more sensitive than ADC to the neurophysiological changes that occur during activation. Looking at the activation maps, the better localization of the activation areas expressed by the \(\gamma\) maps would suggest a greater dependence of \(\gamma\) than BOLD and ADC on the neuronal component that produces cellular swelling and/or a greater sensitivity to local \(\Delta\chi\) changes. However, these observations are the result of experiments performed on only five subjects. These preliminary results need confirmation, which can be obtained from a large cohort of volunteers. Finally, the activated voxels from the \(\gamma\) maps compared with those from the ADC maps showed a tendency towards a higher contrast-to-noise ratio (Figure 2c). In Figure 3, the \(\gamma\) behavior as a function of cell packing \(\phi\) in extravascular tissue and physiological condition highlighted by the \(\Delta\chi\) changes is displayed.