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IEEE SIGNAL PROCESSING MAGAZINE [15] MARCH 2015

very small signals. “We have worked ex-

tensively to improve electrode and amplifi-

er designs so as to stabilize the electrode

characteristics and maximize the possible

recorded SNR,” Taylor says.

Taylor notes that the group’s signal

processing algorithms are still incomplete.

“So far, we have been recording and ana-

lyzing electrically evoked ENG—neural

signals produced by electrical stimula-

tion,” he says. “This is an interesting and

useful exercise, but is an approximation in

several ways to natural neural recording.”

According to Taylor, the amplitude and

SNR of the recorded signals are much

larger than in comparable natural signals.

Additionally, information such as pressure

or joint angle are encoded in neural firing

rates, so identifying the source and direc-

tion of a neural signal is only part of the

overall package necessary to create a com-

plete recording system.

“The impulses generated by electrical

stimulation—compound action potentials

(CAPs)—are synchronized to the stimulat-

ing pulse, so their arrival times are predict-

able,” Taylor says. “The signal processing

algorithms required to interpret them are,

therefore, essentially time invariant and

therefore relatively simple.” Taylor notes

that the researchers have recently begun

modifying their VSR algorithms to include

time dependence, including the ability to

identify not just the velocity and direction

of neural traffic but also the number of im-

pulses in a particular velocity band arriving

per second. “This has required the inclu-

sion of statistical methods in our algo-

rithms that we refer to as velocity spectral

density (VSD),” he says.

The researchers are now looking to

extend their work, which to date has in-

cluded only single acute experiments, to

extensive long-term chronic studies in

nonhuman models. “To achieve this, we

must overcome the surgical, mechani-

cal, and electrical challenges that are

associated with long-term implantation of

electronic devices,” Taylor says. “New

methods will need to be devised to handle

communications and power concerns.”

Since the project is still in a develop-

mental stage, seeking commercial interest

would be premature, Taylor says. “Howev-

er we have good links with the United

Kingdom’s largest commercial manufac-

turer of implanted medical devices, indeed

the only company licensed to produce im-

plantable electronics in this country, and

they are aware of and interested in our

project,” he says. “However, before giving

it to a company for development, we have

still to prove conclusively that VSR is clin-

ically useful.”

Yet Taylor is optimistic that the re-

search will ultimately lead to a widely used

medical technology. “We have tested the

method in animals, and our results are

quite promising so far, although we feel we

are still a long way from a human implant

that could be generally adopted,” he says.

AUTHOR

John Edwards (jedwards@johnedwardsme-

dia.com) is a technology writer based in the

Phoenix, Arizona, area.

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[

society

NEWS

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(continued from page 11)

The IEEE James L. Flanagan Speech

and Audio Processing Award will be present-

ed to Stephen John Young “for pioneering

contributions to the theory and practice of

automatic speech recognition and statistical

spoken dialogue systems.” This award was

founded and is sponsored by the IEEE SPS.

The IEEE Fourier Award for Signal

Processing will be presented to Georgios

B. Giannakis “for contributions to the

theory and practice of statistical signal

processing and its applications to wireless

communications.”

The IEEE Donald O. Pederson Award in

Solid-State Circuits will be presented to

Robert Whitlock Adams “for contributions

to noise-shaping data converter circuits,

digital signal processing, and log-domain

analog filters.”

IEEE medals are the highest honor of

awards presented by the IEEE. The med-

als will be presented at the 2015 IEEE

Honors Ceremony at ICASSP in Brisbane,

Australia. Three SPS members were

awarded with IEEE medals for 2015:

The IEEE Edison Medal recognizes a

career of meritorious achievement in

electrical science, electrical engineering,

or the electrical arts. James Julius Spilker

will be honored “for contributions to the

technology and implementation of civil-

ian GPS navigation systems.”

The IEEE Jack S. Kilby Signal Process-

ing Medal, awarded for outstanding

achievements in signal processing, was

presented to Harry L. Van Trees “for fun-

damental contributions to detections, esti-

mation, and modulation theory; sensor

array processing; and Bayesian bounds.”

The IEEE James H. Mulligan, Jr. Edu-

cation Medal, distributed for a career of

outstanding contributions to education in

the fields of interest of the IEEE, was

awarded to Richard Gordon Baraniuk “for

fundamental contributions to open edu-

cational resources for electrical engineer-

ing and beyond.”

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THE RESEARCHERS

ARE NOW LOOKING

TO EXTEND THEIR WORK,

WHICH TO DATE HAS

INCLUDED ONLY SINGLE

ACUTE EXPERIMENTS, TO

EXTENSIVE LONG-TERM

CHRONIC STUDIES IN

NONHUMAN MODELS.

THE WORLD’S NEWSSTAND

THE WORLD’S NEWSSTAND

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