## 4 Discussion
At higher memory demands, CDA amplitude increased [34]. This result reflects a strong link between memory load and brain activity, in consonance with previous studies [44]. The absence of notable effects of memory load at larger eccentricities can be attributed to spatial limitations in the processing of memory load. Another component of the EEG signal, the power of oscillations in the alpha frequency range, was also explored in visuospatial memory. This revealed a pronounced lateralization of alpha power during the retention phase of the task, with a reduction in power in contralateral compared to ipsilateral signals [34]. This finding aligns with the results of previous research [45]. However, no memory load effects on alpha lateralization were observed, suggesting that the spatial focus of attention, linked to the pattern of alpha power, may operate independently of memory load. This highlights the complex interaction between attention and memory. Interestingly, the authors of the study employed multivariate approaches and observed that alpha power could serve as a decoding mechanism for the level of memory load [34]. This indicates that memory load can be predicted from EEG signals and that multivariate approaches can be useful to detect this information [34]. The frame of reference employed during a spatial memory task has been demonstrated to affect performance, with evidence suggesting that higher general spatial navigation abilities are exhibited when using an allocentric frame of reference than when using an egocentric frame of reference [39]. Moreover, the implication of PC appears to be pivotal for the processing of allocentric information and for the facilitation of transitions between egocentric and allocentric frames. A recent iEEG study observed that the maximum number of allocentric-selective channels were located in the PC when participants were performing a niVR-based spatial judgment task, supporting these results [46]. Furthermore, the associations between PC and frontal, occipital, and central cortical areas suggest a shared processing across these brain regions, with previous reviews showing that both the allocentric and egocentric frames of reference produce activations in different brain cortices, including the OC, the superior temporal cortex, and the PC, as well as the frontal cortex [47]. Additionally, the role of PC in generating spatial maps in a low-frequency range [38] suggests the link between spatial navigation and memory formation with these brain rhythms. Moreover, the discovery that the strength of the spatial maps generated correlated with visuospatial memory performance lends further support to the notion that freely moving during encoding is crucial for obtaining more accurate mental representations, which in turn leads to enhanced visuospatial memory. The role of MTL in spatial memory was also observed in treated epilepsy patients, with the increase of MTL theta band power during spatial memory recall [1]. Moreover, MTL theta oscillations were modulated by the spatial position of objects depending on environmental context and task demands. Taken together, these results suggest a relationship between MTL theta oscillations and spatial memory as well as spatial context-related information. This conclusion is supported by a recent meta-analysis of functional magnetic resonance imaging (fMRI) studies examining the neural substrates of spatial memory encoding and retrieval. The analysis identified activations along various MTL structures [48]. In addition, it is important to highlight that the possibility of measuring MTL neural activity in a free-movement and iVR-based task provides more ecological results and allows for better experimental control of the variables. Learning effects were observed in iVR-based visuospatial memory and spatial navigation tasks in both clinical and healthy samples [1,38].