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Advances in engineering Brain Computer Interfaces

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  • 30-12-2019 2:56am
    #1
    TheSpooner
    Registered Users Posts: 46 ✭


    I have come across a number of scientific papers indicating that brain computer interfaces are trending towards non-invasive technologies such as microwaves.

    The following is from the abstract:

    "Microwave detection technology is one synthesis method involved in physics, electronics and microwave measurement technology. This technique is established on the basis of the electromagnetic characteristics of the media and the physical properties of microwave. A complete microwave detection system for brain activity research consists of a specific antenna array system, data acquisition module, vector network analyzers, as well as computers and other parts...

    ...What's more, the future development tendency of microwave technology for exploring the brain activity is analyzed, especially pointing out the method for rapid diseases diagnosis, researches and development of portable medical devices, as well as trends of combination with brain computer interface."


    The latest research status and prospect on microwave technology for monitoring concerned brain activity
    https://ieeexplore.ieee.org/abstract/document/7237500

    Anyone have experience of BCIs? How do you view these advancements?


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    #2
    TheSpooner
    Registered Users Posts: 46 ✭TheSpooner


    Another paper on detecting neural activity by means of microwaves:

    "Here we present a new detection approach based on microwave technology. The previous works show that the proposed approach gives a hope for human neuronal activities detection and has its own unique advantages and characteristics of non-contact and being nondestructive. In this paper, The novel detection method and its basic principle will be studied and demonstrated first..."

    Microwave transmission approach for human neuronal activities detection
    https://ieeexplore.ieee.org/abstract/document/7761816

    With the appropriate equipment, it would seem that this type of interface is trending towards real-time imaging and, by extension, real-time decoding. Interestingly, nothing fundemental has changed in this field except perhaps the speed of modern computing and the penetration of deep learning into the market over the last decade. So, I'm wondering why this was not a thing before. Anyone know?


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    #3
    TheSpooner
    Registered Users Posts: 46 ✭TheSpooner


    A paper from 2004 outlines one method to read brain activity by focused (or high gain) microwave monitoring of electrical conductivity variations:

    "Focused microwave radiometry, aiming mainly in clinical applications at measuring temperature distributions inside the human body, may provide the capability of detecting electrical conductivity variations at microwave frequencies of excitable cell clusters, such as in the case of brain tissues. A novel microwave radiometric system, including an ellipsoidal conductive wall cavity, which provides the required beamforming and focusing, is developed for the imaging of biological tissues via contactless measurements. The measurement is realized by placing the human head in the region of the first focus and collecting the radiation converged at the second by an almost isotropic dipole antenna connected to a sensitive radiometer operating at 3.5 GHz. In order to compute the focusing properties of the ellipsoidal reflector, an accurate electromagnetic numerical analysis is developed using a semianalytical method. The experimental part of this study focuses on measurements of activation of the primary somatosensory (SI) brain area, elicited during the application of the cold pressor test, a standard experimental condition inducing pain. Analysis of the measured data from 16 healthy subjects suggests that this methodology may be able to pick up activation of the SI during the pain conditions as compared with the nonpainful control conditions. Future research is needed in order to elucidate all the interacting factors involved in the interpretation of the presented results. Finally, potential limitations to the generalization of our results and strategies to improve the system's response are discussed."

    Towards functional noninvasive imaging of excitable tissues inside the human body using focused microwave radiometry
    https://ieeexplore.ieee.org/abstract/document/1318785

    When it comes to decoding brain activity, the same process used in fMRI would work. But rather than attempting to decode based upon blood flow, this proposed method in 2004 would decode based upon electrical conductivity of clusters as they were scanned.


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    #4
    TheSpooner
    Registered Users Posts: 46 ✭TheSpooner


    I think this paper is quite brilliant. Essentially, it describes a type of radar (bistatic) which, in its return signal, captures the electrical conductivity of clusters of neurons in the brain. This would permit the reading and decoding of brain activity of a person, not just within a machine (i.e. fMRI), but also while walking about if we can address the following factors.

    a. Beam spread
    b. Power density in the far field (don't want to cause brain damage)
    c. Cluster tracking (i.e. radar lock), regardless of orientation
    d. Obstructions
    e. Path loss (i.e. better receiver sensitivity)
    f. Simplification of the design to monostatic

    By improving each of the above factors, we can improve the range at which this operates.

    Anyone good with radars?


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    #5
    Turbulent Bill
    Registered Users Posts: 1,622 ✭✭✭Turbulent Bill


    I think the interface method (microwave or other) is moot until the communication protocol is understood.

    As far as I know, we have very limited understanding of what specific electrical signals in the brain mean. If these can't be decoded, creating a man-machine interface isn't going to be useful.


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    #6
    TheSpooner
    Registered Users Posts: 46 ✭TheSpooner


    Turbulent Bill wrote: »
    I think the interface method (microwave or other) is moot until the communication protocol is understood.

    As far as I know, we have very limited understanding of what specific electrical signals in the brain mean. If these can't be decoded, creating a man-machine interface isn't going to be useful.


    Good point. It has been well established that electrical activity of the brain can be decoded. Microwave interfacing, employing electrical conductivity, would be similar to an EEG. An EEG records sum electrical activity, as such is low resolution. Electrical conductivity is more of a material analysis approach, but similar in principle and of much higer resolution.


    This first paper demonstrates EEG can be used to decode hand movement.


    "Research about decoding neurophysiological signals mainly aims to elucidate the details of human motion control from the perspective of neural activity. We performed brain connectivity analysis with EEG to propose a brain functional network (BFN) and used a feature extraction algorithm for decoding the voluntary hand movement of a subject. By analyzing the characteristic parameters obtained from the BFN, we extracted the most important electrode nodes and frequencies for identifying the direction of movement of a hand."
    Decoding Voluntary Movement of Single Hand Based on Analysis of Brain Connectivity by Using EEG Signals
    https://www.frontiersin.org/articles/10.3389/fnhum.2018.00381/full


    This second paper demonstrates that speech can be reconstructed from the human auditory cortex:


    "Auditory stimulus reconstruction is a technique that finds the best approximation of the acoustic stimulus from the population of evoked neural activity. Reconstructing speech from the human auditory cortex creates the possibility of a speech neuroprosthetic to establish a direct communication with the brain and has been shown to be possible in both overt and covert conditions. However, the low quality of the reconstructed speech has severely limited the utility of this method for brain-computer interface (BCI) applications. To advance the state-of-the-art in speech neuroprosthesis, we combined the recent advances in deep learning with the latest innovations in speech synthesis technologies to reconstruct closed-set intelligible speech from the human auditory cortex."
    Towards reconstructing intelligible speech from the human auditory cortex
    https://www.nature.com/articles/s41598-018-37359-z#Abs1


    With the higher resolution of a microwave interface, we can improve upon these interfaces. Just as with the techniques above, some of it is about brain mapping and other portions about training deep neural networks.


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    #7
    TheSpooner
    Registered Users Posts: 46 ✭TheSpooner


    Here is a video on using microwave-based radar as a brain computer interface:



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