Published on: February 16, 2025 / update from: 16. February 2025 - Author: Konrad Wolfenstein
Reading thoughts and AI: Non-invasive brain text decoding and sensors to deep learning architectures of Meta AI-Image: Xpert.digital
The future of human-machine interaction is now-brain signals as a key to communication
Technologies of brain text decoding: a comparison between non-invasive and invasive approaches
The ability to convert thoughts into text represents revolutionary progress in human-computer interaction and harbors the potential to fundamentally improve the quality of life of people with communication impairments. Both the non-invasive Brain2qwerty technology of META AI and invasive electrocorticography (ECOG) aim to achieve this goal by decoding language intentions directly from brain signals. Although both technologies pursue the same overarching goal, they differ fundamentally in their approach, strengths and weaknesses. This comprehensive comparison illuminates the decisive advantages of the non-invasive method without reducing the role and the benefits of invasive procedures.
Security profile and clinical risks: a crucial difference
The most serious difference between non-invasive and invasive brain computer interfaces (BCIS) lies in your security profile and the associated clinical risks. This aspect is of central importance because it significantly influences the accessibility, applicability and long -term acceptance of these technologies.
Avoiding neurosurgical complications: an undeniable advantage of non-invasiveness
Electrocorticography (ECOG) requires a neurosurgical procedure in which electrode arrays are implanted directly to the surface of the brain, below the Dura Mater (the outer brain skin). This intervention, although carried out routinely in specialized centers, carries inherent risks. Statistics show that with such interventions there is a risk of 2 to 5 percent for serious complications. These complications can include a wide range, including:
Intracranial bleeding
Bleeding within the skull, such as subdural hematomas (blood accumulation between dura mater and arachnoid) or intracerebral bleeding (bleeding directly in the brain tissue), can be caused by the operation itself or by the presence of the electrodes. These bleeding can lead to increased brain pressure, neurological deficits and in severe cases even to death.
Infections
Every surgical intervention poses a risk of infection. In the ECOG implantation, wound infections, meningitis or brain tissue (encephalitis) can occur. Such infections often require aggressive antibiotic therapy and, in rare cases, can lead to permanent neurological damage.
Neurological failures
Although the goal of the ECOG implantation is to improve neurological functions, there is a risk that the intervention itself or the placement of the electrodes leads to new neurological deficits. These can manifest themselves in the form of weakness, loss of sensitivity, language disorders, seizures or cognitive impairments. In some cases, these failures can be temporary, but in other cases they can remain permanently.
Anaesthesite -related complications
The ECOG implantation usually requires general anesthesia, which is also associated with its own risks, including allergic reactions, respiratory problems and cardiovascular complications.
In contrast, the MEG/EEG-based approach of META AI completely eliminates these risks. With this non-invasive method, sensors are attached externally on the scalp, similar to a conventional EEG examination. No surgical intervention is required, and all complications mentioned above are eliminated. Clinical studies with the Brain2Qwerty system, which were carried out with 35 subjects, did not have any side effects in need of therapy. This underlines the superior security profile of non-invasive methods.
Long -term stability and hardware failure: an advantage for chronic applications
Another important aspect with regard to clinical applicability is the long -term stability of the systems and the risk of hardware failure. In the case of ECOG electrodes, there is a risk that you will lose functionality over time through tissue confinement or electrical degradation. Studies indicate that Ecog electrodes can have a lifespan of around 2 to 5 years. After this time, an exchange of electrodes may be necessary, which entails another surgical intervention and the associated risks. In addition, there is always the possibility of sudden hardware failure that can end the functionality of the system abruptly.
Non-invasive systems, as developed by META AI, offer a clear advantage in this regard. Since the sensors are attached externally, they are not subject to the same biological mining processes as implanted electrodes. In principle, non-invasive systems offer unlimited maintenance cycles. Components can be exchanged or upgraded if necessary without an invasive procedure being necessary. This long-term stability is particularly crucial for chronic applications, especially in patients with locked-in syndrome or other chronic paralysis states that rely on a permanent communication solution. The need for repeated surgical interventions and the risk of hardware failure would significantly impair the quality of life of these patients and restrict the acceptance of invasive systems for long -term applications.
Signal quality and decoding performance: a differentiated comparison
While security is an undeniable advantage of non-invasive methods, the signal quality and the resulting decoding performance is a more complex field in which both invasive and non-invasive approaches have their strengths and weaknesses.
Spatial-time resolution in comparison: precision vs. non-invasiveness
ECOG systems in which electrodes are placed directly on the cerebral cortex offer an outstanding spatial and temporal resolution. The spatial resolution of ECOG is typically in the range of 1 to 2 millimeters, which means that they can capture neural activity from very small and specific areas of the brain. The temporal resolution is also excellent and is around 1 millisecond, which means that ECOG systems can precisely record extremely fast neural events. This high resolution enables ECOG systems to achieve clinically validated character error rates (CER) of less than 5%. This means that of 100 characters generated with an ECOG-based BCI are fewer than 5 errors. This high accuracy is of crucial importance for effective and liquid communication.
Brain2qwerty, the non-invasive system of META AI, currently achieves drawing errors of 19 to 32%with magnetoencephalography (MEG). Although this is higher error rates compared to ECOG, it is important to emphasize that these values are achieved using a non-invasive method that does not contain surgical risks. The spatial resolution of MEG is in the range of 2 to 3 millimeters, which is somewhat lower than with ECOG, but still sufficient to capture relevant neural signals. The temporal resolution of MEG is also very good and is in the millisecond range.
However, Meta AI has made considerable progress to improve the signal quality and decoding performance of non-invasive systems. These progress is based on three essential innovations:
CNN transformer hybrid architecture
This advanced architecture combines the strengths of Convolutional Neural Networks (CNNS) and Transformer networks. CNNs are particularly effective in the extraction of spatial features from the complex patterns of neuronal activity, which are recorded by MEG and EEG. You can recognize local patterns and spatial relationships in the data that are relevant for the decoding of language intentions. Transformer networks, on the other hand, are excellent in learning and using linguistic context. You can model the relationships between words and sentences across long distances and thus improve the prediction of language intentions based on the context. The combination of these two architectures in a hybrid model makes it possible to effectively use both spatial features and linguistic context in order to increase decoding accuracy.
WAV2VEC integration
The integration of WAV2VEC, a self -monitored learning model for language representations, represents another important progress. WAV2VEC is trained on large quantities of unblooked audio data and learns to extract robust and contextual representations of language. By integrating WAV2VEC into the Brain2qwerty system, the neuronal signals can be compared with these prefabricated language representations. This enables the system to learn the relationship between neuronal activity and linguistic patterns more effectively and to improve decoding accuracy. Self -monitored learning is particularly valuable because it reduces the need for large amounts of labeled training data, which are often difficult to obtain in neuroscience.
Multi-sensor fusion
Brain2qwerty uses synergy effects through the fusion of MEG and high-tight electroencephalogram (HD-EEG). MEG and EEG are complementary neurophysiological measurement techniques. MEG measures magnetic fields that are generated by neural activity, while EEG measures electrical potentials on the scalp. MEG has a better spatial resolution and is less susceptible to artifacts through the skull, while EEG is cheaper and portable. By recording MEG and HD-EEG data and their merger, the Brain2Qwerty system can use the advantages of both modalities and further improve the signal quality and decoding performance. HD-EEG systems with up to 256 channels enable more detailed recording of electrical activity on the scalp and complement the spatial precision of MEG.
Cognitive decoding depth: beyond motor skills
A major advantage of non-invasive systems such as Brain2qwerty lies in its ability to go beyond the pure measurement of motor cortex activity and also to record higher language processes. Ecog, especially placed in motor areas, primarily measures activity that is related to the motor version of language, such as movements of the speech muscles. Brain2qwerty, on the other hand, through the use of MEG and EEG, activity can also be recorded from other brain areas that are involved in more complex language processes, such as:
Correction of typing gliders by semantic prediction
Brain2qwerty is able to correct typing errors by using semantic predictions. The system analyzes the context of the entered words and sentences and can recognize and correctly correct errors. This significantly improves the liquid and accuracy of communication. This ability to predict the semantic suggests that the system not only decodes motor intentions, but also developed a certain understanding of the semantic content of the language.
Reconstruction of complete sentences outside the training set
A remarkable feature of Brain2qwerty is its ability to reconstruct complete sentences, even if these sentences were not included in the original training data set. This indicates a generalization ability of the system that goes beyond the mere memorization of patterns. The system seems to be able to learn underlying language structures and rules and to apply them to new and unknown sentences. This is an important step towards more natural and more flexible brain text interfaces.
Detection of abstract language intentions
In the first studies, Brain2qwerty showed an accuracy of 40% in the detection of abstract language intentions in non-experienced subjects. Abstract language intentions relate to the overarching communicative intention, which is behind a statement, such as "I want to ask a question", "I want to express my opinion" or "I would like to tell a story". The ability to recognize such abstract intentions indicates that non-invasive BCIs could be able to decode not only individual words or sentences in the future, but also to understand the overarching communicative intention of the user. This could lay the basis for more natural and dialog-oriented human-computer interactions.
It is important to note that the decoding performance of non-invasive systems has not yet reached the level of invasive ecog systems. Ecog remains superior in terms of precision and speed of decoding. However, progress in non-invasive signal processing and in deep learning are constantly closing this gap.
Scalability and range of application: accessibility and cost efficiency
In addition to security and decoding performance, scalability and application width play a crucial role in the broad acceptance and social benefits of brain-text decoding technologies. In this area, non-invasive systems show significant advantages over invasive methods.
Cost efficiency and accessibility: reduce barriers
An essential factor that affects the scalability and accessibility of technologies is the costs. Due to the need for surgical intervention, specialized medical devices and highly qualified staff, ECOG systems are associated with considerable costs. The total costs for an ECOG system, including implantation and long-term monitoring, can amount to around € 250,000 or more. These high costs make ECOG systems unaffordable for the width mass and limit their application to specialized medical centers.
In contrast, META AI with its MEG-based solution Brain2qwerty is targeting significantly lower costs. By using non-invasive sensors and the possibility of series production of MEG devices, the aim is to reduce the costs per device to less than € 50,000. This considerable cost difference would make non-invasive BCIs accessible to a much larger number of people. In addition, there is no need for specialized neurosurgery centers in the case of non-invasive systems. The application could be carried out in a wider range of medical facilities and even in the home environment. This is a decisive factor for the care of rural regions and the guarantee of equal access to this technology for people around the world. The lower costs and the greater accessibility of non-invasive systems have the potential to make the brain-text decoding technology from specialized and expensive treatment a broader and more affordable solution.
Adaptive generalizability: personalization vs. standardization
Another aspect of scalability is the question of adaptability and generalizability of the systems. Ecog models usually require individual calibration for each patient. This is because the neuronal signals recorded by ECOG electrodes depend heavily on the individual anatomy of the brain, the placement of the electrodes and other patient-specific factors. The individual calibration can be time -consuming and take up to 40 hours of training per patient. This calibration effort represents a significant hurdle for the wide use of ECOG systems.
Brain2qwerty follows a different approach and uses transfer learning to reduce the need for an elaborate individual calibration. The system is trained on a large data record by MEG/EEG data, which was collected by 169 people. This pre -trained model already contains extensive knowledge of the relationship between neuronal signals and language intentions. For new subjects, only a short adjustment phase of 2 to 5 hours is required to adapt the model to the individual peculiarities of the respective user. This short adjustment phase enables 75% of the maximum decoding performance to be achieved with minimal effort. The use of transfer learning enables significantly faster and more efficient commissioning of non-invasive systems and thus contributes to scalability and application width. The ability to transfer a pre-trained model to new users is a major advantage of non-invasive BCIs with regard to their broad applicability.
Ethical and regulatory aspects: data protection and approval channels
The development and application of brain-text decoding technologies raises important ethical and regulatory questions that must be carefully taken into account. There are also differences between invasive and non-invasive approaches in this area.
Data protection by limited signal yield: protection of privacy
An ethical aspect that is often discussed in connection with BCIS is data protection and the possibility of manipulation of thought. Invasive ECOG systems that enable direct access to brain activity potentially pose a higher risk of abuse of brain data. In principle, ECOG systems could not only be used for decoding language intentions, but also to record other cognitive processes and even manipulation of thoughts by closed loop stimulation. Although the current technology is still far from such scenarios, it is important to keep an eye on these potential risks and to develop suitable protective measures.
Brain2qwerty and other non-invasive systems are limited to passive recording motor intention signals. The architecture is designed to filter out automatically non-language activity patterns. The signals that are caught by the scalp and noisy by MEG and EEG make it technically demanding, extracting detailed cognitive information or even manipulating thoughts. The "limited signal yield" of non-invasive methods can be viewed in a way as the protection of privacy. However, it is important to emphasize that non-invasive BCIS also raise ethical questions, especially with regard to data protection, consent after clarification and the possible abuse of the technology. It is essential to develop ethical guidelines and regulatory framework conditions that ensure the responsible use of all types of BCIS.
Approval path for medical devices: Faster to use
The regulatory way for the approval of medical devices is another important factor that influences the speed with which new technologies can be introduced into clinical practice. Invasive ECOG systems are usually classified as high-risk medical devices because they require surgical intervention and can cause potentially serious complications. Elaborate phase III studies with extensive long-term security data are therefore required for the approval of ECOG systems. This approval process can last several years and require considerable resources.
Non-invasive systems, on the other hand, potentially have a faster admission path. In the United States, non-invasive systems that build on existing EEG/MEG devices can be approved by the 510 (K) process of the Food and Drug Administration (FDA). The 510 (K) process is a simplified admission path for medical devices that are "substantially equivalent" for already approved products. This faster admission path could enable non-invasive brain-text decoding technologies to get clinical application faster and to benefit patients earlier. However, it is important to emphasize that even for non-invasive systems, strict evidence of security and effectiveness are required to obtain approval. The regulatory framework for BCIs is a developing field, and it is important that regulatory authorities, scientists and industry work together to develop clear and appropriate approval channels, promote innovation and at the same time ensure patient safety.
Limits of non-invasive approach: technical challenges remain
Despite the numerous advantages of non-invasive brain-text decoding systems, it is important to also recognize the existing technical hurdles and limits. These challenges must be addressed in order to exploit the full potential of non-invasive BCIs.
Real -time latency
Brain2qwerty and other non-invasive systems currently have a higher latency in decoding than an invasive ECOG systems. Brain2qwerty decodes language intentions only after the end of the sentence, which leads to a delay of about 5 seconds. In comparison, ECOG systems achieve a significantly lower latency of around 200 milliseconds, which enables almost real-time communication. The higher latency of non-invasive systems is due to the more complex signal processing and the need to analyze weaker and more frozen signals. Reducing the latency is an important goal for the further development of non-invasive BCIs to enable more fluid and more natural communication.
Movement artifacts
MEG systems are very sensitive to movement artifacts. Even minor head movements can significantly disrupt the measurements and affect the signal quality. Therefore, the MEG-based data acquisition usually requires a fixed head position, which limits mobile applications. While EEG is less susceptible to movement artifacts, muscle movements and other artifacts can also affect the signal quality. The development of robust algorithms for artifact suppression and the development of portable and moving-tolerant MEG and EEG systems are important research areas to expand the application width of non-invasive BCIs.
Patient compatibility
Non-invasive systems based on the decoding of tip intermarting signals can (as) reach their limits in patients with strongly atrophic motorcycles, such as those in the late stage of amyotrophic lateral sclerosis. In such cases, the motor intention-based decoding can fail because the neuronal signals that are related to tip movements are too weak or no longer present. For these patient groups, alternative non-invasive approaches may be required, which are based, for example, on the decoding of cognitive language processes or on other modalities such as eye control. In addition, it is important to take into account the individual differences in brain activity and the variability of the signal quality between different people in order to make non-invasive BCIs accessible to wider patient population.
Complementary roles in neuroprosthetics: coexistence and convergence
Despite the existing technical challenges and the superior precision of invasive ECOG systems, the non-invasive approach of META AI and other researchers revolutionizes early intervention in the field of neuroprosthetic. Non-invasive BCIs offer the advantage that they can be used low in risk and can be used at the beginning of a disease, such as as. They can offer patients with the beginning of communication difficulties at an early stage and thus improve their quality of life and participation in social life at an early stage.
For the time being, ECOG systems remain irreplaceable for high-precision applications in fully paralyzed patients, especially in locked-in syndrome, in which maximum decoding accuracy and real-time communication are of crucial importance. For this patient group, the potential advantages of invasive BCIs justify the higher risks and costs.
The future of brain computer interfaces could be in convergence between the two technologies. Hybrid systems that combine the advantages of non-invasive and invasive approaches could herald a new era of neuroprosthetics. Such a hybrid approach could, for example, use epidural microelectrodes that are less invasive than ECOG electrodes, but still offer higher signal quality than non-invasive sensors. In combination with advanced AI algorithms for signal processing and decoding, such hybrid systems could close the gap between invasiveness and accuracy and enable a wider range of applications. The continuous further development of both non-invasive and invasive brain text decoding technologies and the research of hybrid approaches promise a future in which people with communication impairments are available to effective, safe and accessible communication solutions.
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