1. What are the contributions mentioned in the paper "Enhancing gesture decoding performance using signals from posterior parietal cortex: a stereo-electroencephalograhy (seeg) study" ?
Here, the authors propose combining iEEG recordings from PPC with that from primary sensorimotor cortex to enhance the gesture decoding performance of iEEG-based BMI.. The authors find that a majority ( L: > 60 %, R: > 40 % ) of electrodes in all the three ROIs present significant activation during the task.. This is the first human iEEG study demonstrating that PPC contains neural information about fine hand movement, supporting the role of PPC in hand shape encoding.. Their findings also demonstrate the early involvement of human PPC in visuomotor task and thus may provide additional implications for further scientific research and BMI applications.. According to the activation along time, the authors further assessed the first activation time of each ROI.. Their results suggest that PPC could be a rich neural source for iEEG-based BMI.
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2. How many electrodes were placed on the extensor carpiradialis muscle?
Electromyography (EMG) signals were acquired by two surface electrodes placed on extensor carpiradialis muscle from the same recording system with SEEG signals simultaneously.
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3. What was the first step of the process mapping?
At the third step, all the process signals were subjected to a 50 Hz comb notch filter to remove the possible line noises and its harmonics.
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4. What is the way to reconstruct hand movement?
Beyond grip type, Menz et al. (2015) reconstructs 27 degrees of freedom representing continuous hand and arm kinematics using spiking activity in AIP of PPC with a correlation coefficient about 0.5 between the reconstructed and actual kinematics, demonstrating a substantial amount of temporal kinematic information in PPC.
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![Figure 4: The neural response of two exemplary electrodes located in different ROIs from subject S1. (A) The z-scored HGP of an electrode located in PPC of left hemisphere during the task. The solid line indicates the mean HGP across 20 trials of each gesture. The shading area indicates the standard error. The dot at the top denotes the significantly activated time windows when r2AS is significant (p < 0.001, FDR corrected) and the asterisk above the lines denotes the significantly selective windows when r2GS is significant (p < 0.05, FDR corrected). (B) The contact location of the PPC electrode in (A). The electrode is rendered as the magenta dot on sagittal and axial MRI images respectively. The Talairach coordinate of this contact is [-49 -37 47]. (C) The z-scored HGP of an electrode located near central sulcus of left hemisphere during the task. Lines and symbols in the figure use the same conventions as (A). (D) The contact location of the primary sensorimotor electrode shown in (C). Same convention as (B). The Talairach coordinate of this electrode is [-31 -25 41].](/figures/figure-4-the-neural-response-of-two-exemplary-electrodes-t2om4ieo.webp)
![Figure 6: Decoding performance with and without PPC. (A/B/C) DA obtained using temporal features drawn from different time period: (A) [-0.5, 0.5] s, (B) [-0.5, 0] s, and (C) [0 0.5] s. Blue: DA computed by using electrodes located at PRC and POC only; Orange: similar to Blue but PPC is also included; Gray : similar to Orange but PPC was randomized across trials and included. For each subject, the errorbars represent the standard error over fOFS (see Sec. 2.6.4). For mean accuracy over the three subjects, the errorbars represent the standard error over the final DA of the three subjects. For A, B, and C, Wilcoxon signed-rank test between with and without PPC shows no significance. p = 0.125 for all. No significance between without and with randomized PPC as well.](/figures/figure-6-decoding-performance-with-and-without-ppc-a-b-c-da-3uoyj4l9.webp)
