Accurately perceiving the gravitational direction is key to successful interaction in our terrestrial environment. In this context field dependence (FD), the importance given to static and/or dynamic visual cues, has largely been discussed. Although first considered a trait, several studies suggest FD be flexible in response to postural or visual contexts and to poor virtual reality user experience. The aim of this study was therefore to determine the influence of a disruptive virtual immersion on the level of static and dynamic FD. Forty-five participants were exposed to a virtual maritime environment for up to 14 minutes.Cybersickness and sense of presence were measured. Before and after virtual immersion, the Rod and Frame Test and the Rod and Disc Test were performed to assess static and dynamic FD respectively. We demonstrated a significant decrease in both levels of FD after immersion in initially more dependent participants. Decrease in static FD was explained by high initial static FD and severe cybersickness, while decrease in dynamic FD was only explained by the initial level of dynamic FD. In this study, we provide evidence confirming FD flexibility, likely reflecting an adaptation process to environmental or individual-related constraints. Yet, static and dynamic FD seem to rely on separate mechanisms, highlighting the necessity to specify which characteristic of visual information (static or dynamic) individuals depend on when assessing their FD. Our results question the reliability of virtual reality for perceptive or motor diagnoses without considering its consequences, specifically in vulnerable populations such as the elderly.
Several studies have shown a significant relationship between smelling and olfactory imagery abilities. The primary aim of the present study was to validate a French version of the Vividness of Olfactory Imagery Questionnaire (VOIQ). The secondary aim was to investigate its capability to differentiate individuals with smell loss from healthy individuals. After having elaborated a French translation of the VOIQ (fVOIQ), we evaluated olfactory imagery abilities of 387 French participants who anonymously self-completed the fVOIQ: 121 pathologic individuals (hyposmic and anosmic), 244 normosmic individuals (healthy non-expert), and 22 fragrance experts. Significant split-half reliability as expressed by Spearman correlation coefficients for the global sample, as well as for each group separately, indicated the excellent internal consistency of the fVOIQ. Moreover, results revealed a significant effect of the smelling ability group on fVOIQ score, suggesting that daily olfactory stimulation is fundamental to maintaining the ability to create a vivid image and that severe loss of smell may result in progressive impairment of olfactory imagery. Our fVOIQ and the original English version seemingly have similarly high benefit in differentiating experts and normosmic individuals based on their olfactory imagery ability. Moreover, the fVOIQ seems capable of differentiating individuals with loss of smell from healthy individuals. These findings demonstrate the reliability and validity of the fVOIQ, and its capability to differentiate individuals’ smelling ability according to their olfactory imagery ability.
Psychogenic Non-Epileptic Seizures (PNES) are a misunderstood and disabling pathology, characterized by a paroxysmal occurrence of clinical signs without the epileptic activity. Resting-state functional MRI (fMRI) studies in patients with PNES have shown abnormal functional connectivity of the resting-state networks, especially in the limbic and motor systems, and in the precuneus. However, the transient nature of PNES episodes prevents us from elucidating the underlying mechanisms of seizures. Here, we report the case of a patient who presented an atonic episode of PNES during a 3T fMRI session. The patient is a 23-year-old woman, suffering from post-traumatic stress disorder, with no neurological comorbidities. The preprocessing of the fMRI images involved realignment, co-registration, segmentation, normalization, denoising (PhysIO toolbox), and smoothing. The time boundary of the seizure was defined according to the patient's reports, and the seizure period was contrasted with the resting state period before the seizure. A whole-brain analysis showed significant activations (left inferior temporal gyrus, left temporo-occipital junction) and deactivations (right precuneus, right superior parietal lobule, right postcentral gyrus, bilateral lingual gyri, inferior occipital gyri, and cerebellar lobules; right insula in a sub-thresholded analysis). Activations and deactivations occurred in four cerebral networks: emotional processing, agency, self-perception, and dissociation. To our knowledge, this report is the first published case of functional MRI during PNES. These results could confirm the emotional and dissociative hypothesis of the physiopathology of PNES and highlight future targets for neuromodulation.
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