An exploratory fNIRS study with immersive virtual reality: a new method for technical implementation

For over two decades Virtual Reality (VR) has been used as a useful tool in several fields, from medical and psychological treatments, to industrial and military applications. Only in recent years researchers have begun to study the neural correlates that subtend VR experiences. Even if the functional Magnetic Resonance Imaging (fMRI) is the most common and used technique, it suffers several limitations and problems. Here we present a methodology that involves the use of a new and growing brain imaging technique, functional Near-infrared Spectroscopy (fNIRS), while participants experience immersive VR. In order to allow a proper fNIRS probe application, a custom-made VR helmet was created. To test the adapted helmet, a virtual version of the line bisection task was used. Participants could bisect the lines in a virtual peripersonal or extrapersonal space, through the manipulation of a Nintendo Wiimote ® controller in order for the participants to move a virtual laser pointer. Although no neural correlates of the dissociation between peripersonal and extrapersonal space were found, a significant hemodynamic activity with respect to the baseline was present in the right parietal and occipital areas. Both advantages and disadvantages of the presented methodology are discussed

Altered social attention in anorexia nervosa during real social interaction

The capacity to devote attentional resources in response to body-related signals provided by others is still largely unexplored in individuals with Anorexia Nervosa (AN). Here, we tested this capacity through a novel paradigm that mimics a social interaction with a real partner. Healthy individuals (Experiment 1) and individuals with AN (Experiment 2) completed a task with another person which consisted in performing, alternatively, rapid aiming movements to lateralised targets. Generally, this task leads to a form of Inhibition of Return (IOR), which consists of longer reaction times when an individual has to respond to a location previously searched by either himself (individual IOR) or by the partner (social IOR) as compared to previously unexplored locations. IOR is considered as an important attentional mechanism that promotes an effective exploration of the environment during social interaction. Here, healthy individuals displayed both individual and social IOR that were both reliable and of the same magnitude. Individuals with AN displayed a non-significant individual IOR but a reliable social IOR that was also significantly stronger than individual IOR. These results suggest the presence of a reduced sensitivity in processing body-related stimuli conveyed by oneself in individuals with AN which is reflected in action-based attentional processes

Exploring the role of primary and supplementary motor areas in simple motor tasks with fNIRS

Studies employing functional magnetic resonance imaging (fMRI) have highlighted a covariation between the amplitude of hemodynamic responses recorded in primary and supplementary motor areas (M1 and SMA) and the duration of a motor task. A subset of these studies have hinted to a possible functional dissociation between processing carried out in these areas, with SMA primarily involved in action preparation, while M1 involved in action execution. This proposed functional dissociation was explored in the present study using a different technique—functional near-infrared spectroscopy—which enabled a finer-grained monitoring of the temporal characteristics of the hemodynamic response compared to fMRI. Here, hemodynamic responses in M1 and SMA were recorded in 7 participants during a right-finger tapping task of short (1 s) or long (3 s) duration. Hemodynamic responses of larger amplitude were recorded from both contralateral M1 and SMA during long-duration than short-duration tapping. Furthermore, the analysis of the temporal profiles of these responses revealed a more sustained and prolonged activity for long-duration versus short-duration tapping in M1, but not in SMA. Rather than functionally dissociable areas, the present results are more compatible with the hypothesis that M1 and SMA subserve different, though strongly interacting, functional subroutines subtended in motor task preparation and execution

Number-space interactions in the human parietal cortex: Enlightening the SNARC effect with functional near-infrared spectroscopy

Interactions between numbers and space have become a major issue in cognitive neuroscience, because they suggest that numerical representations might be deeply rooted in cortical networks that also subserve spatial cognition. The spatialnumerical association of response codes (SNARC) is the most robust and widely replicated demonstration of the link between numbers and space: in magnitude comparison or parity judgments, participants reaction times to small numbers are faster with left than right effectors, whereas the converse is found for large numbers. However, despite the massive body of research on numberspace interactions, the nature of the SNARC effect remains controversial and no study to date has identified its hemodynamic correlates. Using functional near-infrared spectroscopy, we found a hemodynamic signature of the SNARC effect in the bilateral intraparietal sulcus, a core region for numerical magnitude representation, and left angular gyrus (ANG), a region implicated in verbal number processing. Activation of intraparietal sulcus was also modulated by numerical distance. Our findings point to number semantics as cognitive locus of numberspace interactions, thereby revealing the intrinsic spatial nature of numerical magnitude representation. Moreover, the involvement of left ANG is consistent with the mediating role of verbal/cultural factors in shaping interactions between numbers and space