Electrical Stimulation of Brain Boosts Birth of New Cells

ScienceDaily (Sep. 22, 2011) — Stimulating a
specific region of the brain leads to the production of new brain cells that
enhance memory, according to an animal study in the September 21 issue of
The Journal of Neuroscience. The findings show how deep brain
stimulation (DBS) — a clinical intervention that delivers electrical pulses to
targeted areas of the brain — may work to improve cognition. Read more.

Hot Wavelets

The paper "Emerging Applications of Wavelet: a review", by Akansu, Serdijn and Selesnick has been declared the hottest (No. 1) paper in Computer Science, Physical Communication (Elsevier) over the period from October 2009 to September 2010. Over the past 9 months, the paper held its No. 1 position firmly, so it is thus heading for becoming the hottest paper for two consecutive years!

ELCA Festival, 2012 Edition will be on Friday, January 13

PSSST! Mark your calendar!

I’m back!

After one year of absence since I graduated for my master thesis, I can happily tell you that I’ m back :). On September 1 I started my PhD research on neural readout circuitry in cochlear implants.

The project is a collaboration between Delft University of Technology and Leiden University Medical Center and is funded by STW (Dutch Technology Foundation). It is called ReaSONS (Realtime Sensing of Neural Signals). Within this project we aim to develop new technology to record the evoked Compound Action Potential (eCAP) generated by the hair cells in the cochlea.

As soon as I have my first results I will let you know. Stay tuned!

Cees-Jeroen

Transcutaneous Vestibular Stimulator

Vestibular stimulators stimulate the vestibular organ (located in the ‘labyrinth of the inner ear’) and can therefore have a direct effect on the balance of a person. Triggered by some movies that show the impressive and funny effects that Vestibular Stimulators can offer, our group decided to build a very simple stimulator to experience the effects ourselves. We also have been informed that there might be interest for this type of stimulators for medical experiments, so there’s more behind it than just fun.

Transcutaneous Vestibular Stimulation uses electrodes that are put behind the ear of the subject (being ourselves in our experiments) and a current is injected. We decided to make the stimulator remote controlled to give the subject more freedom.

We could keep writing a lot more about this stimulator, but movies might be much more self explaining and fun to watch. Therefore, simply click the following link to see the effects of Vestibular Stimulators:

Movie 1

Movie 2

Marijn

The Voices of DAC—A chip in your brain?

Jan Rabaey, UC Berkeley, about brain-machine interfaces. Click here to watch the video.

This talk covers a little bit of transcutaneous signal and energy transfer, recording of brain signals, polymer electrode arrays, brain waves, EEG, ECoG, epilepsy, neurostimulation, DBS, 65nm, microwatt, pulsed waveform, temperature rise, digital amplifier, subthreshold logic, interference, frequency agile radios, security, neural dust…

Wouter

Timing in the brain not only a matter of time

In the Proceedings of the Royal Society B (Biology) of August 10, 2011, interested readers can read in an article by James Heron that  "duration perception […] may be mediated via a system of duration-selective ‘channels’, which
are differentially activated depending on the match between afferent
duration information and the channels’ ‘preferred’ duration." This is an interesting postulation which may, however, be incorrect, as, to the best of my knowledge (though I am not a physician), there are no particular channel-like structures associated with our sensors (ears and eyes) that can be held responsible for our understanding of how long a particular event lasts. 

From a mathematical and engineering perspective it is also known that there exists a strong relation between time and frequency, taught to us in high school when we learn about the meaning of T = 1/f, T being the period of a (periodical) signal and f its frequency. Some people are known for having an "absolute pitch", sometimes erroneously called "absolute hearing", in the sense that they recognize exactly the pitch of a tone they hear. Most people do not have this remarkable talent, but are nevertheless still pretty good at estimating the approximate pitch of a tone they hear.

Also, it is known that events seem to last longer when they are dull or not exciting and its opposite is probably best illustrated by the expression "time flies when you’re having fun", Also, and this many of us have experienced during the ELCA music festival of last March, sometimes, when excited, a little bit tensed or under pressure, musicians have a tendency to play their songs faster, with more beats per minute, without being aware of it. Apparently, in a more stressful situation, our notion of time becomes related to a faster clock, or a shorter time duration. Finally, it is known that when people are feverish, also their notion of time changes.

The above relation between time and frequency and thus pitch and the experience of time and frequency stretch depending on our excitement, suggest, at least to me, that our notion of time is not so much related to a static entity in the form of a channel, but rather is linked to our internal oscillatory processes, as, e.g., happen in the brain between its various hierarchical layers, or in our lifesupporting master clock, the heart. It would be interesting to see whether the above states of excitement also affect the frequency of our brain waves (alpha, beta and gamma waves). If so, the issue of reliable tinnitus detection (see Senad’s previous post) may become more patient and situation-specific and thus more difficult to implement.

Stay tuned 😉

Wouter

A first proof-of-principle of a Tinnitus detector circuit

Tinnitus is a condition in which a patient perceives an auditory phantom sound that can take the form of ringing, buzzing, roaring or hissing in the absence of an external sound. Approximately a billion of people suffer from tinnitus worldwide, while in 2% – 3% of the population, tinnitus significantly degrades quality of life of the patients and can lead to insomnia, anxiety and depression.

Currently, there are no proven treatments for tinnitus. However, recent research has shown that tinnitus patients can benefit from electrical brain stimulation. In addition, it has been shown that there is a link between tinnitus perception and a change in the energy levels of several electrocortigography (ECoG) / electroencephalography (EEG) frequency bands. For example, the energies of theta (4-8Hz) and low-gamma (30-50Hz) waves increase, while the energy of alpha (8-12Hz) waves decreases during active tinnitus perception. The same studies suggest that the intensity of the tinnitus perception correlates with the amount of the energy increased in the gamma band.

The real-time tinnitus detection method proposed by the BME group detects tinnitus by comparing ECoG/EEG signal energies from different locations in the brain according to a tinnitus "signature". First, the proposed strategy selects appropriate ECoG/EEG bands per channel by means of band-pass filters. Next, their extracted energies are compared to their counterparts from a different (healthy) location. Tinnitus is detected only if higher theta and gamma energies while lower alpha energy is found when compared to the signals from this healthy region. The applicability of the detector is verified by means of circuit simulations with real neural waveforms and is able to successfully detect tinnitus.

Are you interested in any progress related to the tinnitus detector circuit? Stay tuned.

Senad 

Small chip to overcome inflammation of joints

Today, the Telegraaf and Nu.nl report that a team of the Dutch rheumatologist Paul-Peter Tak of the Amsterdam Academic Medical Center will implant a kind of pacemaker, its size in the order of a bout a square centimeter, that will deliver stimuli to the vagus nerve for about one minute a day. By doing so, it is expected that inflammation of the joints of patients that suffer from rheumatoid arthritis can be reduced or even completely stopped.

Of course, what can be deduced from the article is that this pacemaker, electronics-wise, is nothing more than a simple blinking light with a timer, which can be implemented by means of a miniature microcontroller and a battery. However, it is also obvious that electrical stimulation of the vagus nerve, albeit at its infancy, is already very promising and a possible treatment of a wide range of neural disorders and pain is dawning at the horizon.

Wouter

Be gentle to the heart, otherwise you’ll lose it

Researchers at the Max Planck Institute and Cornell University have come up with a low-energy pulse sequence to
restart hearts and make implants last longer is what we can read in IEEE Spectrum today. Other advantages of using a train (a burst) of pulses instead of using a single (tonic) pulse are that defibrillation becomes less painful to the patient and is less likely to evoke fibrillation elsewhere in the heart. The new therapy still has to be tested on patients, though. 

From this, it is only a small step towards realizing that other types of tissue should be stimulated with burst-like or even more exotic yet gentle pulses, too. In the Biomedical Electronics Group of Delft University of Technology, we’re working on interfacing with the brain in a more natural manner. Stay tuned…

Wouter