## 1 Introduction  
Virtual reality is proving to be an important way to transpose people in space and time to provide them with strong sensory and emotional experiences with considerable psychological impact. Multisensory environments were originally proposed in studies of patients with cognitive and behavioral impairments [1] and have provided encouraging results, particularly in facilitating learning [2]. Within this paradigm, it has been proposed that the human brain has evolved to develop, learn, and function optimally in multisensory environments; therefore, multisensory training is a better approximation of the natural setting [3]. The more sensory-enriched the multisensory virtual environment created, the more realistic the exposure and, consequently, the psychological effects. Several experimentshave tested the effectiveness of multisensory VR exposure in alleviating stress through meditation. [PERSON] et al. [4] used a 3D Malaysian environment combined with Islamic ritual prayer and soothing sounds, while [PERSON] et al. [5] used the Malaysian 3D environment combined with [PERSON] music, soothing breathing exercises, and relaxing audio sounds. Both experiments found that the multisensory VR conditions induced a better meditative state compared to the traditional meditation procedure. Studying the effectiveness of a more complex multisensory VR method in inducing presence as well as relaxation, [PERSON] et al. [6] used VR images, odors, and haptic stimuli individually, VR combined with odor, or VR combined with haptic stimuli. In this experiment, they used, as tactile stimulus, artificial grass made of plastic and synthetic materials with a thick and abundant texture, which made the tactile sensation as similar to natural grass as possible. They found that all conditions were equally effective in terms of relaxation, but adding haptic stimuli to VR resulted in a better state of presence. Virtual reality has emerged as a promising tool in therapeutic settings, particularly in the treatment of anxiety disorders, post-traumatic stress disorder (PTSD), and phobias. [PERSON] [7] explored the therapeutic potential of VR combined with odors and concluded that this multisensory VR is an effective way to treat anxiety, stress, and pain in combination with standard psychotherapeutic and pharmacological approaches. Related to the impact of VR technology in reducing the level of stress by manipulating autobiographical memory (and implicitly changing the way memories are currently perceived), there are several studies worth highlighting, some of which we will present below. In a relatively recent study, [PERSON] et al. [8] investigated how the impact of focusing on the spatiotemporal context of aversive autobiographical memories reduces negative emotions, appraisals, and re-experiencing symptoms in subjects with post-traumatic stress disorder. They found a significant decrease in re-experiencing symptoms in the following week, and subjects with a higher subjective sense of memory distancing reported less re-experiencing. It should be noted that this study used simple VR, not multisensory. An important question remains as to whether the addition of multisensory components changes or amplifies the effect obtained through simple VR. Hence, in a review from 2021 [9], one of the most important authors from the field of odor-evoked autobiographical memory, [PERSON], demonstrated how olfaction could be incorporated into VR technology to make it a more efficient intervention. She noted that although VR technology has already been successfully used to treat PTSD, it has not been associated with odor. The author proposed as a possible intervention the coupling of VR with odor and the use of this combination for the reappraisal of a traumatic memory. She proposed that due to the uniquely emotional features of olfactory processing and odor-evoked memory, olfaction combined with VR is excellently positioned to be effectively used in the treatment of this disorder.