Neuroscience of Virtual Reality: From Virtual Exposure to Embodied Medicine

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On October 10, I will gave a keynote at Vancouver, during the Interface Health Summit, discussing how Virtual Reality can hack our mind and our body, and why it can give birth to a radically new generation of tools for health care.

The Interface Health Summit, is a two-day event created to engage, inform, inspire and connect the world’s digital health innovators. This year you can enjoy amazing talks; meet the pioneers of VR and AR therapies and experts in AI, Precision Health and Digital Therapeutics. A summary of my talk is presented below.

As suggested recently by Forbes, "Virtual Reality Isn't Just For Gamers Anymore; It Will Change Your Health":

"VR has the potential to radically change and substantially improve health-related behavior, and thus radically improve health and wellbeing, by equipping individuals with new and powerful tools to make smart decisions and engage in healthier behavior."

But when and how?

According to the "2018 AUGMENTED AND VIRTUAL REALITY SURVEY REPORT" by Perkins Coie, the interest for VR in the health care community is increasing and it is now the only expected growing area for investments, second only to the gaming community.

As noted by another recent report - The Global Augmented Reality (AR) and Virtual Reality (VR) in Healthcare Market Opportunities 2018 - high cost of products and devices was the major factor restraining growth of the global virtual reality in healthcare market. In addition, lack of skilled professionals, data security and privacy concerns are other factors expected to hamper growth of the global market to a certain extent over the forecast period.

North America accounts for highest share in the global virtual reality in healthcare market in terms of revenue and is expected to maintain its position over the forecast period. Increasing government and private funding towards development of these technologies, presence of major manufacturers and vendors in this region, and early adoption of these technology are major factors driving growth of the North America market. The Europe market accounts for second highest revenue share in the global market and is expected to witness considerable growth over the next 10 years. 

For these reasons, another report - the "Virtual Reality (VR) in Healthcare Market: Global Industry Analysis, Trends, Market Size and Forecasts up to 2023" - suggests that the healthcare market will grow with a CAGR of 54.5% over the forecast period ending in 2023.

However, it is true that research is pushing VR, especially in the mental health world. And now - as I just described in the recently published "Neuroscience in Virtual Reality" paper - more than 25 different systematic reviews and meta-analyses support the clinical potential of this technology in both the diagnosis and the treatment of mental health disorders: VR compares favorably to existing treatments in anxiety disorders, eating and weight disorders, and pain management, with long-term effects that generalize to the real world.

More, the availability of a new generation of wireless and/or standalone headsets - from the high-end Vive Pro to the low cost Oculus Go (199 US$) or the Lenovo Mirage Solo (US$ 399) - may generate more advanced and user-friendly applications, that can be more easily used in a health-care setting.

A list of the top VR health companies was recently compiled by Medical Futurist and it is available here. And more are approaching. From big ones like Invivo, to smaller ones like NeuroTrainer or Softcare Studios.

But why is VR so effective? In the paper I suggested the following answer: VR shares with our brain the same basic mechanism, embodied simulations (see below a lesson of Prof. Gallese discussing it).

An increasingly popular hypothesis—predictive coding (see also the box below) —suggests that the brain actively maintains an internal model (simulation) of the body and the space around it, which provides predictions about the expected sensory input and tries to minimize the amount of prediction errors (or “surprise”).

This simulation has two key characteristics.

1. First, different from other internal models used in cognitive science—such as Tolman's cognitive maps or Johhson–Laird's internal models—they are simulations of sensory motor experiences. In this view, they include visceral/autonomic (interoceptive), motor (proprioceptive), and sensory (e.g., visual, auditory) information.
2. Second, embodied simulations reactivate multimodal neural networks, which have produced the simulated/expected effect before. This approach is used not only for actions, but also for concepts and emotions. Specifically, a concept is a group of distributed multimodal “patterns” of activity across different populations of neurons (motor, somatosensory, limbic, and frontal areas) that support a goal achievement. So, the simulation of a concept involves its reenactment in modality-specific brain areas. Moreover, the brain uses emotion concepts to categorize sensations. As underlined by Barrett, “That is, the brain constructs meaning by correctly anticipating (predicting and adjusting to) incoming sensations. Sensations are categorized so that they are (a) actionable in a situated way and therefore (b) meaningful, based on past experience. When past experiences of emotion (e.g., happiness) are used to categorize the predicted sensory array and guide action, then one experiences or perceives that emotion (happiness).”(p.9)

In this view, the brain creates multiple multisensory simulations to predict: (a) upcoming sensory events both inside and outside the body, and (b) the best action to deal with the impending sensory events. Moseley and colleagues also suggested that these simulations are integrated with real-time sensory data in the “body matrix,” an embodied simulation of the body in the world.

As I detailed in a recent paper for Cortex, this virtual body is produced through the integration of sensory data, arriving from real-time multiple sensory modalities and internal bodily information, with the predictions made using the stored information about the body from conceptual, perceptual and episodic memory (see below).

Usually this model works well, but if for some reasons it is impaired the predictions are wrong and the individual may experience mental problems (see also below). For example, experience pain in a virtual body that does not match the real one (phantom limb pain). I also recently suggested in Frontiers in Human Neuroscience that this mechanism is a critical factor in the etiology of eating disorders

To sum up, according to neuroscience our brain, to effectively regulate and control the body in the world, creates an embodied simulation of the body in the world used to represent and predict actions, concepts and emotions.

Virtual Reality works in a similar way: it uses computer technology to create a simulated world that individuals can manipulate and explore as if they were in it. In other words, the VR experience tries to predict the sensory consequences of your movements showing to you the same scene you will see in the real world.

Specifically, VR hardware tracks the motion of the user, while VR software adjusts the images on the user's display to reflect the changes produced by the motion in the virtual world. To achieve it the VR system, like the brain, maintains a model (simulation) of the body and the space around it. This prediction is then used to provide, using the VR hardware, the expected sensory input. Obviously, to be realistic, the VR model tries to mimic as much as possible the brain model: the more the VR model is similar to the brain model, the more the individual feels present in the VR world.

This suggests that Virtual Reality is able to fool the predictive coding mechanisms using by our brain generating the feeling of presence  in a virtual body and in the digital space around it (to deepen the concept of presence please check  this paper and  this free book).

Up to now, VR has been used to simulate external reality, that is, to make people feel “real” what is actually not really there (i.e., the environment). However, the ability of VR to fool the predictive coding mechanisms that regulate the experience of the body also allows it to make people feel “real” what they are not.

In other words, VR can offer new ways for structuring, augmenting, and/or replacing the experience of the body for clinical goals. 

Moreover, it may offer new embodied ways for assessing the functioning of the brain by directly targeting the processes behind real-world behaviors.

Finally, if concepts are embodied simulations, and VR is an embodied technology, it should be possible to facilitate cognitive modeling and change by designing targeted virtual environments able to modify concepts from both outside and inside.

But what is the real clinical potential of VR as an embodied technology? According to neuroscience, the body matrix serves to maintain the integrity of the body at both the homeostatic and psychological levels by supervising the cognitive and physiological resources necessary to protect the body and the space around it. Specifically, the body matrix plays a critical role in high-end cognitive processes such as motivation, emotion, social cognition, and self-awareness, while exerting a top-down modulation over basic physiological mechanisms such as thermoregulatory control and the immune system.

In this view, different authors have recently suggested that an altered functioning of the body matrix and/or its related processes might be the cause of different neurological and psychiatric conditions, like autism, depression, eating disorders and schizophrenia.

Specifically, VR can be the core of a new trans-disciplinary research field—“Embodied Medicine”—the main goal of which is the use of advanced technology for altering the body matrix, with the goal of improving people's health and well-being.

Nevertheless, at the moment, there is a critical shortcoming that is limiting this possibility: VR simulates the external world/body but not the internal one.

Recently, I also introduced the concept of “sonoception” (www.sonoception.com), a novel noninvasive technological paradigm based on wearable acoustic and vibrotactile transducers able to stimulate both mechanoreceptors in different parts of the body—the stomach, the heart, the muscles—and the otolith organs of the vestibular system.

The first technology we developed using this approach is an interoceptive stimulator that is both able to assess interoceptive time perception in clinical patients and to enhance heart rate variability (the short-term vagally mediated component—rMSSD) through the modulation of the subjects' parasympathetic system. 

The integration of these technologies with VR in a multisensory simulative platform will allow the modulation of both the external and internal bodily information, to structure, augment and/or replace the contents of our bodily self-consciousness.

In conclusion, even if VR is already a reality in behavioral health, the possibility of using it to simulate both the external and internal world may open new clinical options in the near future able to target the experience of the body and its related processes directly.

Psychosomatics is an interdisciplinary field that explores the relationships between psychosocial, behavioral factors, and bodily processes. The long-term goal of the vision presented in this article is the use of simulative technologies—both simulating the external world and the internal one—to reverse engineer the psychosomatic processes that connect mind and body.

If achieved, this perspective will provide a radically new meaning to the classical Juvenal's Latin dictum “Mens sana in corpore sano” (a healthy mind in a healthy body) by allowing a new trans-disciplinary research field—“Embodied Medicine”—that will use advanced multisensory technologies to alter bodily processes for enhancing homeostasis and well-being.

BOX: Virtual Reality and Predictive Coding

How does Virtual Reality work? A virtual reality headset shows you a virtual world and as soon as you move your body it modifies the virtual world you are seeing to make it seem like you're really there. In other words, the virtual reality software tries to predict the sensory consequences of your movements showing to you the same scene you will see in the real world. This is the same approach using by our brain: according to the predictive coding framework the brain produces a  Bayesian estimate of the environment.For this specific case this means that, whenever a movement is executed, the (mental representation of the) movement is associated with (the mental representation of) its predicted effects (  ideomotor approach). In this view virtual reality is the best tool to correct/modify the predictive coding behavior in our brain.

The mechanisms behind the prediction of the effects of a behavior were originally explored in the work of Professor Karl Friston (see his lesson and some key papers below).

References

Predictive coding under the free-energy principle

K Friston, S Kiebel - … of the Royal Society of London …, 2009 - rstb.royalsocietypublishing.org

This paper considers prediction and perceptual categorization as an inference problem that is solved by the brain. We assume that the brain models the world as a hierarchy or cascade of dynamical systems that encode causal structure in the sensorium. 

Predictive coding or evidence accumulation? False inference and neuronal fluctuations

G Hesselmann, S Sadaghiani, KJ Friston… - PloS One, 2010 - journals.plos.org

Perceptual decisions can be made when sensory input affords an inference about what generated that input. Here, we report findings from two independent perceptual experiments conducted during functional magnetic resonance imaging (fMRI).

The free-energy principle: a unified brain theory?

K Friston - Nature Reviews Neuroscience, 2010 - nature.com

A free-energy principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and physical (for example, information theory and optimal control theory) sciences from the free-energy perspective.