Scientists induce sensations of touch and movement in the arm of a paralyzed man

April 10, 2018, California Institute of Technology
fMRI is used to highlight select implant sites in the somatosensory cortex. Electrodes implanted in this region were able to stimulate neurons that produced physical sensations, like a squeeze or tap, in the arm of a paralyzed man. Credit: Andersen lab

For the first time, scientists at Caltech have induced natural sensations in the arm of a paralyzed man by stimulating a certain region of the brain with a tiny array of electrodes. The patient has a high-level spinal cord lesion and, besides not being able to move his limbs, also cannot feel them. The work could one day allow paralyzed people using prosthetic limbs to feel physical feedback from sensors placed on these devices.

The research was done in the laboratory of Richard Andersen, James G. Boswell Professor of Neuroscience, T&C Chen Brain-Machine Interface Center Leadership Chair, and director of the T&C Chen Brain-Machine Interface Center. A paper describing the work appears in the April 10 issue of the journal eLife.

The is a strip of brain that governs bodily sensations, both proprioceptive sensations (sensations of movement or the body's position in space) and cutaneous sensations (those of pressure, vibration, touch, and the like). Previous to the new work, neural implants targeting similar brain areas predominantly produced sensations such as tingling or buzzing in the hand. The Andersen lab's implant is able to produce much more natural via intracortical stimulation, akin to sensations experienced by the patient prior to his injury.

The patient had become paralyzed from the shoulders down three years ago after a spinal cord injury. Two arrays of tiny electrodes were surgically inserted into his somatosensory cortex. Using the arrays, the researchers stimulated neurons in the region with very small pulses of electricity. The participant reported feeling different natural sensations—such as squeezing, tapping, a sense of upward motion, and several others—that would vary in type, intensity, and location depending on the frequency, amplitude, and location of stimulation from the arrays. It is the first time such natural sensations have been induced by intracortical neural stimulation.

"It was quite interesting," the study participant says of the sensations. "It was a lot of pinching, squeezing, movements, things like that. Hopefully it helps somebody in the future."

Though different types of stimulation did indeed induce varying sensations, the neural codes governing specific physical sensations are still unclear. In future work, the researchers hope to determine the precise ways to place the electrodes and stimulate somatosensory brain areas in order to induce specific feelings and create a kind of dictionary of stimulations and their corresponding sensations.

The next major step, according to Andersen, is to integrate the technology with existing neural prosthetics. In 2015, Andersen's laboratory developed brain-machine interfaces (BMIs) to connect a prosthetic robotic arm to electrodes implanted in the region of the brain that governs intentions. In this way, a paralyzed man was able to utilize the prosthetic arm to reach out, grasp a cup, and bring it to his mouth to take a drink. Connecting the device with the somatosensory cortex would create bidirectional BMIs that would enable a paralyzed person to feel again, while using .

"Currently the only feedback that is available for neural prosthetics is visual, meaning that participants can watch the brain-controlled operation of robotic limbs to make corrections," says Andersen. "However, once an object is grasped, it is essential to also have somatosensory information to dexterously manipulate the object. Stimulation-induced somatosensory sensations have the potential added advantage of producing a sense of embodiment; for example, a participant may feel over time that the robotic limb is a part of their body."

The study is titled "Proprioceptive and Cutaneous Sensations in Humans Elicited by Intracortical Microstimulation."

Explore further: US military develops prosthetic hand that can 'feel'

More information: Michelle Armenta Salas et al, Proprioceptive and cutaneous sensations in humans elicited by intracortical microstimulation, eLife (2018). DOI: 10.7554/eLife.32904

Related Stories

US military develops prosthetic hand that can 'feel'

September 14, 2015
Researchers fitted a man who has been paralyzed for more than a decade with an experimental prosthetic hand that lets him "feel" sensations, the US military's futuristic development department said.

Sense of touch reproduced through prosthetic hand

May 10, 2013
In a study recently published in IEEE Transactions on Neural Systems and Rehabilitation Engineering, neurobiologists at the University of Chicago show how an organism can sense a tactile stimulus, in real time, through an ...

Amputees can learn to control a robotic arm with their minds

November 27, 2017
A new study by neuroscientists at the University of Chicago shows how amputees can learn to control a robotic arm through electrodes implanted in the brain.

The neural codes for body movements

July 21, 2017
A small patch of neurons in the brain can encode the movements of many body parts, according to researchers in the laboratory of Caltech's Richard Andersen, James G. Boswell Professor of Neuroscience, Tianqiao and Chrissy ...

Potential brain-machine interface for hand paralysis

January 15, 2018
A brain-machine interface that combines brain stimulation with a robotic device controlling hand movement increases the output of pathways connecting the brain and spinal cord, according to a study of healthy adults published ...

Brain-machine interfaces: Bidirectional communication at last

February 22, 2017
A prosthetic limb controlled by brain activity can partially recover the lost motor function. Neuroscientists at UNIGE asked whether it was possible to transmit the missing sensation back to the brain by stimulating neural ...

Recommended for you

New ALS therapy in clinical trials—drug extends survival, reverses some neuromuscular damage in animals

July 16, 2018
About 20,000 people in the United States are living with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. The invariably fatal disease kills the nerve cells that control walking, eating and breathing. ...

Convergence of synaptic signals is mediated by a protein critical for learning and memory

July 16, 2018
Inside the brain, is a complex symphony of perfectly coordinated signaling. Hundreds of different molecules amplify, modify and carry information from tiny synaptic compartments all the way through the entire length of a ...

Synapse-specific plasticity governs the identity of overlapping memory traces

July 16, 2018
Memories are formed through long-term changes in synaptic efficacy, a process known as synaptic plasticity, and are stored in the brain in specific neuronal ensembles called engram cells, which are activated during corresponding ...

'Concussion pill' shows promise in pre-clinical pilot study

July 16, 2018
In 2016, funded by a $16 million grant from Scythian, the multidisciplinary Miller School team embarked on a five-year study to examine the effects of combining CBD (a cannabinoid derivative of hemp) with an NMDA antagonist ...

Fetal gene therapy prevents fatal neurodegenerative disease

July 16, 2018
A fatal neurodegenerative condition known as Gaucher disease can be prevented in mice following fetal gene therapy, finds a new study led by UCL, the KK Women's and Children's Hospital and National University Health System ...

Rehabilitating the mind could improve outcomes after spinal cord injury

July 16, 2018
A study led by Heriot-Watt University has explored how individuals with spinal cord injuries perceive the space around them. The findings suggest additions are needed to the rehabilitation programmes adopted post-injury to ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.