Difference in Somatosensory Event-Related Potentials in the Blind Subjects Leads to Better Performance in Tactile P300 BCI

Abstract In this study, we created 8-command P300 tactile brain-computer interface, running on minimally modified consumer Braille display, and tested it on 10 blind subjects and 10 sighted controls with two stimuli types, differing in size. Larger stimuli provide better BCI performance both in blind and sighted participants than smaller stimuli. With large stimuli, median target selection accuracy in the blind group was 95%, which is 27% more than sighted controls (p &lt; 0.05), suggesting that blind subjects are not only able to use tactile brain-computer interface but also can achieve superior results in comparison with sighted subjects. The difference in event-related potentials between groups is located in frontocentral sites around 300 ms post-stimulus and corresponds with early cognitive event-related potential components. Blind subjects have higher amplitude and shorter latency of ERPs. This effect was consistent across stimuli types. This is the first study to evaluate differences in event-related potentials between blind and sighted subjects in a BCI-specific task.</jats:p

Difference in somatosensory event-related potentials in the blind subjects leads to better performance in tactile P300 BCI

AbstractIn this study, we have created an 8-command P300 tactile BCI with two stimuli types, running on a minimally modified consumer Braille display and tested it on 10 blind subjects and 10 sighted controls. Blind subjects have demonstrated 27% higher median accuracy than sighted controls (p&lt; 0.05), proving that the blind subjects are not only able to use tactile BCI but also can achieve superior results in comparison with sighted subjects. Median accuracy in the blind group with the best stimuli type has reached 95%. The difference in event-related potentials between groups is located in frontocentral sites before 300 ms post-stimulus and corresponds with early cognitive ERP components. The blind subjects have higher amplitude and lower latency of ERPs. This result is consistent through experimental conditions with different tactile stimuli. The classification performance for the blind subjects is correlated with Braille reading speed. This enables a discussion about mechanisms of plastic changes during sensory compensation after vision loss and its dependence on personal perceptual experience.Author summarySensory compensation following vision loss can be recognized as a unique model for neural plasticity. However, the magnitude of the effect and the specific tasks where it’s manifested is still a subject for debate. In this study, we have created a tactile brain-computer interface game to study how somatosensory processing is different between the blind and the sighted people. The participants were required to attend to tactile stimuli, and the correct stimulus was selected using realtime EEG classification. We have shown, for the first time, that the blind subjects are significantly better than the sighted in tactile brain-computer interface tasks. We have also found, that individual performance is correlated with Braille proficiency. This result links personal perceptual abilities in two different sensory tasks. EEG analysis revealed that differences in performance can be attributed to early cognitive processing steps. Along with practical considerations in brain-computer interface development, the results also add to the data on cognitive processing in the blind and enable the discussion on the importance of Braille education.</jats:sec

Single-Subject TMS Pulse Visualization on MRI-Based Brain Model: A precise method for mapping TMS pulses on cortical surface

Highly accurate visualization of the points of transcranial magnetic stimulation (TMS) application on the brain cortical surface could provide anatomy-specific analysis of TMS effects. TMS is widely used to activate cortical areas with high spatial resolution, and neuronavigation enables site-specific TMS of particular gyrus sites. Precise control of TMS application points is crucial in determining the stimulation effects. Here, we propose a method that gives an opportunity to visualize and analyze the stimulated cortical sites by processing multi-parameter data. • This method uses MRI data to create a participant's brain model for visualization. The MRI data is segmented to obtain a raw 3D model, which is further optimized in 3D modeling software. • A Python script running in Blender uses the TMS coil's orientation data and participant's brain 3D model to define and mark the cortical sites affected by the particular TMS pulse. • The Python script can be easily customized to visualize TMS points task-specifically

Genetic screening of Russian Usher syndrome patients toward selection for gene therapy

Background: Usher syndrome (USH) is heterogeneous in nature and requires genetic test for diagnosis and management. Mutations in USH associated genes are reported in some populations except Russians. Here, we first time represented the mutation spectrum of a Russian USH cohort. Methods: Twenty-eight patients with USH were selected from 3214 patients from Deaf-Blind Support Foundation “Con-nection” during 2014–2016 following the observational study NCT03319524. Complete ophthalmologic, ENT, and vestibular medical tests were done for clinical characterization. NGS, MLPA, and Sanger sequencing were considered for genetic analysis. Results: Around 53.57% and 39.28% patients had USH1 and USH2, respectively; 17.85% cases (n = 5/28) had no known mutation. Eleven (73.33%) subjects showed variations in USH1 associated genes MYO7A (72.72%), CDH23 (9.09%), PCDH15 (9.09%), and USH1C (9.09%). Eleven mutations are detected in MYO7A where 54.54% are novel. MYO7A: p.Q18* was most frequent (27.27%) mutation and is associated with early manifestation and most severe clinical picture. Two novel mutations (p.E1301* and c.158-?_318+?del) are detected in PCDH15 gene. Around 90.90% patients suspected to be USH2 are confirmed by genetic testing. Eleven mutations detected in the USH2A gene, where 27.27% were novel. Most common USH2A mutation is p.W3955* (50%) followed by p.E767fs, p.R1653*, and c.8682-9A> G (20% each). Conclusion: The Russian USH cohort shows both novel and known USH mutations. Clinically the prevalence of USH2 is low (39.28%) and the frequency of MYO7A mutations responsible for USH1B is very high (63.63%, N = 7/11) compared to other cohorts. These seven patients carrying MYO7A mutations are preliminarily eligible for the UshStat® gene therapy.</p