## 1 Introduction
Such devices serve to enhance the level of immersion experienced by users by isolating them from their physical surroundings, thereby providing a more controlled and immersive experimental environment [15]. Specifically, immersive systems often incorporate advanced features such as motion tracking, stereoscopic vision, and auditory feedback, which contribute to a heightened sense of presence and immersion [16; 17; 18]. For instance, systems that utilize precise motion tracking enable users to navigate and interact within a 3D space, fostering a more realistic experience [16; 19]. Additionally, iVR can be enhanced through the integration of haptic feedback devices, which simulate touch and physical sensations, further bridging the gap between the virtual and real worlds [19; 20]. Examples of commercially available iVR systems are the HTC Vive and Meta Quest. HTC Vive uses external base stations with Lighthouse technology for precision tracking, achieving sub-millimeter accuracy through infrared signals detected by the headset and controllers. It supports room-scale tracking, allowing for free movement within a defined space. High-resolution displays with up to a 120 Hz refresh rate ensure smooth visuals and reduce motion sickness. The Meta Quest is a standalone VR system designed to provide wireless VR experiences without requiring a PC or external sensors. Powered by the Qualcomm Snapdragon XR2 platform, it delivers high-quality visuals and responsive performance. Integrated cameras enable inside-out tracking, mapping the environment and user movements, enhancing portability, and eliminating the need for external tracking devices. The experience of immersion can also be implemented by mixed reality (MR) that merges virtual content with the real world in an interactive, immersive way [21]. The Microsoft HoloLens is an example of a MR device that blends holographic projections with the physical environment to create an interactive immersive experience. The neural substrates of visuospatial memory encompass multiple brain regions, including the dorsolateral prefrontal cortex (dIPFC) and the parietal cortex, which are involved in the processing of spatial information [22]. Studies also found that medial temporal lobe (MTL) regions, such as the hippocampus, participate in visuospatial tasks [23]. The study of brain activity during the performance of a visuospatial memory task with electrophysiological and functional neuroimaging techniques can provide valuable insights into the involvement of brain areas required during the task and offer a deeper understanding of this cognitive process. With the purpose of studying brain function and connectivity, a variety of techniques have been developed. These include neuroimaging methods, such as functional magnetic resonance imaging (fMRI); optical imaging methods, such as functional near-infrared spectroscopy (fNIRS); and electrophysiological techniques, including electroencephalography (EEG) and magnetoencephalography (MEG). EEG is an electrophysiological technique that measures the neural activity from the scalp potentials. It is a widely used research and clinical tool for monitoring brain function and detecting anomalies [24; 25]. MEG is an additional electrophysiological technique based on the recording of magnetic fields through dense arrays of sensors [24]. Both techniques allow for the measurement of functional connectivity in the human brain with a high temporal resolution, although with a low spatial resolution [24]. On the other hand, fNIRS is an optical imaging technique that employs near-infrared light to measure cortical hemodynamics, that is, the relative changes in the concentration of oxygenated and deoxygenated hemoglobin secondary to neuronal activity [26; 27]. Research has demonstrated the efficacy of integrating EEG and fNIRS with iVR, resulting in valuable insights into diverse cognitive, behavioral, and motor functions [28; 29].