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Los Angeles ACM Chapter Meeting

Wednesday, June 6, 2001

Cognitive Neural Prosthetics

by Daniella Meeker
 and Shiyan Cao
Caltech

In the past decade, there have been great strides taken in developing a brain-computer interface for the purpose of prosthetic systems. Most systems under development utilize the fact that networks of cells in the brain communicate with electro-chemical impulses. These signals are either mimicked with electrical stimulation or detected with electrodes in order to introduce sensory input that might be lacking (as in blindness) or detect the volition for an output that cannot be executed (as in paralysis). With such an interface we can tap into existing knowledge about the brain in order to develop engineered systems that might aid patients of blindness and paralysis. 
Ms. Meeker will discuss the basis for these biological signals, how knowledge of signals is being applied to develop prostheses, and the current research in Richard Andersen's laboratory devoted to developing a motor prosthetic based on the cognitive signals present in the parietal cortex. 

Daniella Meeker is a 3rd year graduate student in the Computation and Neural Systems Program at Caltech. She received her undergraduate degree in Neuroscience from the University of Chicago. 

 The program was "Cognitive Neural Prosthetics" presented by Daniella Meeker and Shiyan Cao. Both of them are graduate students at Caltech. The motivation of this research is to eventually aid people with neurological disorders such as stroke, ALS, or spinal cord injuries by rerouting signals from the brain around the damaged area and delivering neural commands to either the natural arm, by microstimulating muscles, or to a prosthetic arm. The initial research is accomplished using monkeys.

Daniella began the presentation by describing research on neural prosthetics, which use signals from the brain to control and operate prosthetic devices. Monkeys have been trained to play simple video games where the monkey fixates on a cue and presses buttons. Recordings are made by inserting a tiny electrode through the brain until a signal is isolated from a single neuron. Since the brain does not contain pain receptors the monkey does not feel pain. Part of the brain reacts when the monkey thinks about reaching and there are high frequency spikes when the target is perceived to be in the preferred direction and there are low frequency waves they are riding on top of. There is another peak in activity when the monkey reaches for the target. The activity of each brain cell is spatially selective and information can be extracted from different frequency bands. The monkey reacts to external cues when he sees the target and then generates a control signal that moves a prosthetic arm. The monkey relies on visual feedback

The second part of the talk was given by Shiyan Cao, a Mechanical Engineering graduate student, who explained the details of the devices and how signal processing was done to operate the device. They started out with a Bayesian probabilistic model and then modified the model as a result of experimental tests. The objectives were to observe the differences in signals from the brain for the "target observed" and "no target" conditions to determine the underlying states that could be used for control of the prosthetics and that would ignore "visual transients" that might occur if the monkey’s attention shifted during the test. They were able to use a finite state machine approach where the prosthetic reach was broken up into discrete movements.

For more details go on line to:

www.erc.caltech.edu

and follow the paths to the research report "Toward Prosthetic Systems Controlled by Parietal cortex" which describes the procedures in detail.

This was tenth meeting of the LA Chapter year. Several people came from considerable distance specifically for this fine presentation.

 


The Los Angeles Chapter normally meets the first Wednesday of each month at the Ramada Hotel, 6333 Bristol Parkway, Culver City. The program begins at 8 PM.   From the San Diego Freeway (405) take the Sepulveda/Centinela exit southbound or the Slauson/Sepulveda exit northbound.

6:30 p.m.  Social Hour

7:00 p.m. Dinner

8:00 p.m.  Presentation

The menu choices are listed in the table above.

To make a reservation, call or e-mail John Radbill, (818) 353-8077, and indicate your choice of entree, by Sunday before the dinner meeting.

There is no charge or reservation required to attend the program. Parking is FREE!

For membership information, contact Mike Walsh, (818)785-5056 or follow this link.


Other Affiliated groups

SIGAda   SIGCHI SIGGRAPH  SIGPLAN

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