How Do You Know Whether You Perceive Pain the Same as Others?

How much pain are you in on a scale from one to 10?

This simple method is still the way pain is measured in doctors' offices, clinics, and hospitals-but how do I know if my five out of 10 is the same as yours?

A new, early-stage platform aims to more objectively measure and share our individual perception of pain. It measures brain activity in two people in order to understand how their experiences compare and recreate one person's pain for the other. The platform was developed as a partnership between the large Tokyo-based telecommunications company NTT Docomo and startup PaMeLa, short for Pain Measurement Laboratory, in Osaka, Japan.

It's part of a project from Docomo called Feel Tech. We are developing a human-augmentation platform designed to deepen mutual understanding between people," a Docomo representative told IEEE Spectrum by email. (Answers were originally provided in Japanese and translated by Docomo's public relations.) Previously, we focused on sharing movement, touch, and taste-senses that are inherently difficult to express and communicate. This time, our focus is on pain, another sense that is challenging to articulate."

Docomo demonstrated the platform last month at the Combined Exhibition of Advanced Technologies (CEATEC), Japan's largest electronics trade show.

How Shared Pain Perception Tech Works

The system consists of three components: a pain-sensing device, a platform for estimating the difference in sensitivity, and a heat-based actuation device.

First, the system uses electroencephalography (EEG) to measure brain waves and uses an AI model to visualize" pain as a score between 0 and 100, for both the sender and receiver. The actuation device is then calibrated based on each person's sensitivity, so a sensation transmitted to both people will feel the same.

In this initial version, the platform works with thermally induced pain stimuli. This method allows for precise adjustment and ensures safety during research and development," Docomo says. PaMeLa also used thermal stimulation in its research on determining the intensity level of pain, which graded the pain stimulation data of 461 subjects with machine learning algorithms.

However, the company says, pain from other sources can also be shared. Eventually, Docomo aims to convey many types of physical and even psychological pain, which will be an aim of future research. We believe there are various possibilities for how pain can be captured and shared," Docomo says.

Finding a Use Case for Shared Pain Perception

The technology is still at a very early stage, says Carl Saab, the founder and director of the Cleveland Clinic Consortium for Pain. Saab, who is also an adjunct professor at Brown University, researches pain biomarkers, including through EEG measurements and AI.

For one thing, Saab says he's not clear what the use case is for the platform. In terms of the science, he also notes that pain differs in healthy patients and those experiencing ongoing pain, such as chronic pain or migraine. If you induce pain in a healthy volunteer versus somebody who's a pain patient, the nature of the representation of pain in the brain is different," Saab says. Healthy volunteers know that the pain will be temporary, he explains. But in real patients, chronic pain often comes with anxiety, depression, and sometime side effects from medication.

In a study Saab conducted several years ago, for example, he induced pain by submerging volunteers' arms in ice for an extended period. When he did the same with pain patients, the resulting brain activity was much more complex, and the signals weren't so clear.

Docomo says it plans to collaborate with hospitals in the future to verify the technology in medical settings. And in March, PaMeLa announced it completed a clinical trial that analyzed changes in EEG signals before and after administration of painkillers in patients receiving surgeries under general anesthesia. The startup is also investigating pain in other conditions, such as exercise, acute pain from injections, and chronic pain.

Pain is a multidimensional experience," Saab says. When you say you're measuring someone's pain, you always have to be careful about what kind of dimension you are measuring."