How do we plan movements? While
we rarely think about the neural processes behind movement, doing things such as opening
a door, picking up a pen, and walking require the ability for our brains to not
only carry out the movement of muscles, but to carry them out in the correct
order. For example, when throwing a ball, we intuitively know to move our arm back,
pitch it forward, and then release. Imagine if we got the order wrong, and
instead released the ball before pitching our arm forward? Carrying out the correct order of actions is crucial to daily living, which is a concept that was highlighted by the
talk given by Dr. Lawrence Behmer, who has done extensive research into the
cognitive and neural processes behind action planning and execution. In his talk,
he spoke of a study he did that involved testing two models for sequence
production in movement, the simple serial chaining model and the inhibitory
control model. He tested this using transcranial magnetic stimulation (TMS) and
electroencephalography (EEG). In said study he recruited typists to type 5
letter words and non-words and tracked their right index finger across 5 letter
positions. His results resembled the inhibitory
control model, which states that activation in serial ordering tasks is on a
gradient where activation lessens as you continue on.
During his talk, he highlighted
several uses for technology that takes advantage of the neural signals involved in movement. For example, he discussed how technology is now being made for controlling
toys using EEG signals, such as cars and helicopters. He also mentioned prosthetic devices, something that caught my attention as I am very interested in robotics and technology that can be neurally integrated.
According to the Shirley Ryan
Ability Lab, nearly 30 million people around the world are in need of prosthetic
devices to replace lost limbs. Whether someone has lost an arm due to cancer,
or their legs from a car accident, the impact on one’s life after the loss of a
limb is severe, causing them to lose the ability to do some of the things they
were able to do beforehand. A prosthetic, which is an artificially made body part,
can often bring back some of the movements previously lost. For example,
prosthetic legs can make it possible to walk again, and a prosthetic arm can
make it possible to grab objects. Yet most prosthetics that are currently available are not perfect substitutes for the limbs they are meant to replace. For example, during
his talk, Dr. Behmer showed a video of a woman with a prosthetic arm grabbing a
water bottle and bringing it towards her to drink it. Said prosthetic would be unable to pick up the water bottle, however, if
it were to be moved, as it was specifically programmed for picking up the bottle from a specific distance and orientation. The prosthetic was severely limited in its range of motion
and controllability, especially in comparison to a real arm.
However, much research is currently being done to design prosthetic devices as close as possible
to real limbs in usability. One such effort is being made by the Applied
Physics Laboratory at John Hopkins University, where they have developed a
device known as the MPL (modular prosthetic limb) in response to a challenge
issued by DARPA (Defense Advanced Research Projects Agency) to create an effective and "naturally controlled" prosthetic arm. This device in its current version uses 17 motors and hundreds of sensors to manage 26 degrees of freedom, and is able to move almost as effectively as a human arm. This device is said to be one of the most advanced prosthetics in the world. In terms of capturing signals from the brain, the lab is focusing on creating effective neural interfaces, such as one that can be implanted near the primary motor cortex.
One man in Florida who lost his arm due to cancer has been living with one of these devices since December of 2017 as a part of APL's Revolutionizing Prosthetics program. He is the first person to live with one of these devices, and is able to use the device to achieve movements such as holding the hands of family members, and is even attempting to learn how to play the piano. As of now, while the device cannot get wet, and can be expensive to fix and maintain, (As it's worth 120 million dollars!) the information being gathered from him using the device on a daily basis will be crucial in further developing advanced prosthetics.
Works Cited:
No comments:
Post a Comment