WALL AND MELZACK'S TEXTBOOK OF PAIN, revised under new editorial leadership, and with a host of new, multidisciplinary international contributors ...

Wall and Melzack's textbook of pain

As virtual reality (VR) technology and systems become more commercially available and accessible, more and more psychologists are starting to integrate VR as part of their methods. This approach offers major advantages in experimental control, reproducibility, and ecological validity, but also has limitations and hidden pitfalls which may distract the novice user. This study aimed to guide the psychologist into the novel world of VR, reviewing available instrumentation and mapping the landscape of possible systems. We use examples of state-of-the-art research to describe challenges which research is now solving, including embodiment, uncanny valley, simulation sickness, presence, ethics, and experimental design. Finally, we propose that the biggest challenge for the field would be to build a fully interactive virtual human who can pass a VR Turing test - and that this could only be achieved if psychologists, VR technologists, and AI researchers work together.

Why and how to use virtual reality to study human social interaction: The challenges of exploring a new research landscape.

Perception as Bayesian Inference

Current theories suggest that physical pain and social rejection share common neural mechanisms, largely by virtue of overlapping functional magnetic resonance imaging (fMRI) activity. Here we challenge this notion by identifying distinct multivariate fMRI patterns unique to pain and rejection. Sixty participants experience painful heat and warmth and view photos of ex-partners and friends on separate trials. FMRI pattern classifiers discriminate pain and rejection from their respective control conditions in out-of-sample individuals with 92% and 80% accuracy. The rejection classifier performs at chance on pain, and vice versa. Pain- and rejection-related representations are uncorrelated within regions thought to encode pain affect (for example, dorsal anterior cingulate) and show distinct functional connectivity with other regions in a separate resting-state data set (N = 91). These findings demonstrate that separate representations underlie pain and rejection despite common fMRI activity at the gross anatomical level. Rather than co-opting pain circuitry, rejection involves distinct affective representations in humans.

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Separate neural representations for physical pain and social rejection

Clinical utility and prospective of TMS–EEG

Recent research has shown that experiencing events that represent a significant threat to social bonds activates a network of brain areas associated with the sensory-discriminative aspects of pain. In the present study, we investigated whether the same brain areas are involved when witnessing social exclusion threats experienced by others. Using a within-subject design, we show that an ecologically valid experience of social exclusion recruits areas coding the somatosensory components of physical pain (posterior insular cortex and secondary somatosensory cortex). Furthermore, we show that this pattern of activation not only holds for directly experienced social pain, but also during empathy for social pain. Finally, we report that subgenual cingulate cortex is the only brain area conjointly active during empathy for physical and social pain. This supports recent theories that affective processing and homeostatic regulation are at the core of empathic responses.

Empathy for social exclusion involves the sensory-discriminative component of pain: a within-subject fMRI study

Neuroanatomical basis of concern-based altruism in virtual environment.

The placebo effect is a component of any response to a treatment (effective or inert), but we still ignore why it exists. We propose that placebo analgesia is a facet of pain perception, others being the modulating effects of emotions, cognition and past experience, and we suggest that a computational understanding of pain may provide a unifying explanation of these phenomena. Here we show how Bayesian decision theory can account for such features and we describe a model of pain that we tested against experimental data. Our model not only agrees with placebo analgesia, but also predicts that learning can affect pain perception in other unexpected ways, which experimental evidence supports. Finally, the model can also reflect the strategies used by pain perception, showing that modulation by disparate factors is intrinsic to the pain process.

/pdf/a-bayesian-perspective-on-sensory-and-cognitive-integration-2npi858bk7.pdf

A Bayesian perspective on sensory and cognitive integration in pain perception and placebo analgesia.

Parietal cortex subserves various cognitive tasks, ranging from attention to visuo-motor skills. It is part of a parieto-frontal network involved in attention, and part of the visual dorsal stream, opposed to the visual ventral stream, although increasing evidence suggests interchange of information between them. In this study, co-registration of Transcranial Magnetic Stimulation (TMS) and Electroencephalographic activity (EEG) has been used to investigate the spreading of cortical connections from the parietal cortex in healthy volunteers. TMS on the left parietal cortex activated a network of prefrontal regions in the contra-lateral hemisphere in a time range of 102-167 ms after the stimulus. Moreover, activation in the ipsi-lateral middle temporal and fusiform gyri was observed at 171-177 ms after delivery of TMS. Findings suggest the existence of late driven connections between parietal and prefrontal regions that could partially represent the neural pathway related to attention, even if, in this experiment, no attentional processing was requested. Late connections between dorsal and ventral streams were also evident, confirming previous evidence about interchange of information between them. Conclusively, the present investigation confirms that a great amount of information spreads from parietal cortex to different regions in the brain, supporting the idea that connections are more complex and articulated than those proposed. Present findings also suggest that the simultaneous recording of EEG during the application of TMS is a promising tool for the study of connections in the brain.

Marco Zanon

Papers

Empathy for social exclusion involves the sensory-discriminative component of pain: a within-subject fMRI study

Neuroanatomical basis of concern-based altruism in virtual environment.

A Bayesian perspective on sensory and cognitive integration in pain perception and placebo analgesia.

Cortical connections between dorsal and ventral visual streams in humans: Evidence by TMS/EEG co-registration.

Predicting response originality through brain activity: An analysis of changes in EEG alpha power during the generation of alternative ideas