Ultrasound, advanced techologies in Neuroscience and Haptic Interface

Earthside Massive is a strong supporter of using sound frequencies to make life a more enjoyable experience through music, but most of us don’t give much thought to the sound frequencies we can’t hear. In that regard, let’s take another look at ultrasound and see what it is and where it’s going as a technology.

According to Wikipedia:

Ultrasound

Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults and thus, 20 kHz serves as a useful lower limit in describing ultrasound. The production of ultrasound is used in many different fields, typically to penetrate a medium and measure the reflection signature or supply focused energy. The reflection signature can reveal details about the inner structure of the medium. The most well known application of this technique is its use in sonography to produce pictures of fetuses in the human womb. There are a vast number of other applications as well.

Ability to hear ultrasound

The upper frequency limit in humans (approximately 20 kHz) is caused by the middle ear, which acts as a low-pass filter. Ultrasonic hearing can occur if ultrasound is fed directly into the skull bone and reaches the cochlea without passing through the middle ear. Carefully-designed scientific studies have been performed and confirmed what they call the hypersonic effect – that even without consciously hearing it, high-frequency sound can have a measurable effect on the mind.^{[citations needed]}

It is a fact in psychoacoustics that children can hear some high-pitched sounds that older adults cannot hear, because in humans the upper limit pitch of hearing tends to become lower with age.^{[1] [2][3]} A cell phone company has used this to create ring signals supposedly only able to be heard by younger humans^[4]; but many older people claim to be able to hear it, which is likely given the considerable variation of age-related deterioration in the upper hearing threshold.

Some animals – such as dogs, cats, dolphins, bats, and mice – have an upper frequency limit that is greater than that of the human ear and thus can hear ultrasound.

Aside from the traditional uses of ultrasound there are a growing number of emerging technologies utilizing it in different ways. Recently William “Jamie” Tyler from Arizona State University has led his team investigating the ability to remotely control brain circuits with the use of a low powered form of pulsing ultrasound. Here are a few excerpts from a recent article in Physorg.com:

In a twist on nontraditional uses of ultrasound, a group of neuroscientists at Arizona State University has developed pulsed ultrasound techniques that can remotely stimulate brain circuit activity. Their findings, published in the Oct. 29 issue of the journal Public Library of Science (PLoS) One, provide insights into how low-power ultrasound can be harnessed for the noninvasive neurostimulation of brain circuits and offers the potential for new treatments of brain disorders and disease.

“We were able to unravel how ultrasound can stimulate the electrical activity of neurons by optically monitoring the activity of neuronal circuits, while we simultaneously propagated low-intensity, low-frequency ultrasound through brain tissues,” says Tyler, assistant professor of neurobiology and bioimaging in the School of Life Sciences in the College of Liberal Arts and Sciences.

Led by Tyler, the ASU research group discovered that remotely delivered low intensity, low frequency ultrasound (LILFU) increased the activity of voltage-gated sodium and calcium channels in a manner sufficient to trigger action potentials and the release of neurotransmitter from synapses. Since these processes are fundamental to the transfer of information among neurons, the authors pose that this type of ultrasound provides a powerful new tool for modulating the activity of neural circuits.

One prior stumbling block to using ultrasound noninvasively in the brain has been the skull. However, the acoustic frequencies utilized by Tyler and his colleagues to construct their pulsed ultrasound waveforms, overlap with a frequency range where optimal energy gains are achieved between transcranial transmission and brain absorption of ultrasound – which allows the ultrasound to penetrate bone and yet prevent damage to the soft tissues. Their findings are supported by other studies examining the potential of high-intensity focused ultrasound for ablating brain tissues, where it was shown that low-frequency ultrasound could be focused through human skulls.

When asked about the potential of using his groups’ methods to remotely control brain activity, Tyler says: “One might be able to envision potential applications ranging from medical interventions to use in video gaming or the creation of artificial memories along the lines of Arnold Schwarzenegger’s character in ‘Total Recall.’ Imagine taking a vacation without actually going anywhere

“Obviously, we need to conduct further research and development, but one of the most exhilarating prospects is that low intensity, low frequency ultrasound permit deep-brain stimulation procedures without requiring exogenous proteins or surgically implanted medical devices,” he adds.

Tyler and the other ASU researchers will now focus on further characterization of the influence of ultrasound on intact brain circuits and translational research, taking low intensity ultrasound from the lab into pre-clinical trials and treatment of neurological diseases.

Source: Arizona State University

In addition to amazing medical potential there are a growing number of interesting abstract projects with Ultrasound as well. Takayuki Iwamoto of Tokyo University has developed a haptic device that can project ultrasound in a way that creates the sensation of touching a virtual object. Many applications can be envisioned for this, and Iwamoto’s team is working on the commercialization of it within the video gaming industry. Check out this video from Shinoda Lab for a visualization of the effect:

These two examples present incredible new insights into what may be possible in the future with ultrasound. I’m looking forward to having a tri-quarter with the ability to affect my neurotransmitters and haptic interfaces with virtual reality like environments. We’ll see where it goes

What do you think about these new ultrasound advancements?

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