Knowledge Vault 3/9 - GTEC BCI & Neurotechnology Spring School 2024 - Day 1
Running EP experiments: auditory, visual, vibro-tactile
Slobodan Tanackovic, g.tec medical engineering GmbH (AT)
<Resume Image >

Concept Graph & Resume using Claude 3 Opus | Chat GPT4 | Llama 3:

graph LR classDef lecture fill:#f9d4d4, font-weight:bold, font-size:14px; classDef paradigm fill:#d4f9d4, font-weight:bold, font-size:14px; classDef subject fill:#d4d4f9, font-weight:bold, font-size:14px; classDef eeg fill:#f9f9d4, font-weight:bold, font-size:14px; classDef evoked fill:#f9d4f9, font-weight:bold, font-size:14px; A[Slobodan Tanackovic] --> B[Slobodan, Tina lecture: evoked potentials. 1] A --> C[Paradigm presenter app
shows stimuli. 2] C --> D[Vibrotactile P300: left target,
right non-target. 3] C --> E[Auditory: tones, similar
to N100 clicks. 4] C --> F[Visual N170: face/object
images, center gaze. 5] A --> G[Prepare subject: comfort,
no movement/tension. 6] G --> H[Position EEG cap: midline,
Cz at vertex. 7] H --> I[Active cap electrodes,
earlobe reference. 8] I --> J[Apply gel: expose scalp,
fill, avoid bridging. 9] A --> K[g.Recorder: view EEG,
select amp/channels. 10] A --> L[Demo: Andras EEG file
in EEGLAB. 11] L --> M[Import locations, plot,
filter, epoch data. 12] M --> N[Reject noisy epochs,
baseline, ERP/average plots. 13] M --> O[N100 auditory on Cz
after averaging. 14] A --> P[Slides: evoked potentials,
paradigm software. 15] P --> Q[Triggering: parallel port,
software, LSL. 16] A --> R[64-ch visual example: raw,
averaged real-time. 17] R --> S[Visual N170: 170ms
occipital/parietal, P100, Cz. 18] R --> T[Similar results with
g.Nautilus dry electrodes. 19] A --> U[Demo: Simulink for real-time
EPs, EEG blocks. 20] U --> V[g.HIamp amp, vibrotactile
paradigm settings. 21] V --> W[Eyes closed alpha:
good EEG signal. 22] V --> X[Vibrotactile: left targets
counted by subject. 23] U --> Y[Simulink: acquisition, paradigm,
processing blocks. 24] A --> Z[LSL not ideal for precise
ERP timing. 25] A --> AA[Sampling rate based on
expected ERP latency. 26] A --> AB[g.BSanalyze: HRV stress
from ECG, EEG. 27] A --> AC[Precise ERP: g.TRIGbox
parallel port, E-Prime. 28] A --> AD[Video: passive electrode
gelling technique. 29] AD --> AE[Ideal gel amount: cover
electrode, no bridging. 30] class A,B,P,Q lecture; class C,D,E,F,U,V,W,X,Y paradigm; class G,H subject; class I,J,K,L,M,N,O,R,S,T,Z,AA,AB,AC,AD,AE eeg; class R,S evoked;


1.-The lecture is by Slobodan and Tina on evoked potentials - visual, auditory, and vibrotactile.

2.-They use a paradigm presenter application to show stimuli. It's important to give clear task instructions to subjects.

3.-For the vibrotactile P300 paradigm, left pulse vibrations are the target and right ones are non-target.

4.-The auditory paradigm presents tone stimuli, similar to the clinical N100 evoked potential test that uses clicks.

5.-The visual N170 face/object paradigm shows images while the subject looks at the screen center.

6.-Preparing the subject involves seating them comfortably in a non-moving chair with no muscle tension.

7.-The EEG cap should be positioned properly, with the midline electrode aligned with the nose and Cz over the vertex.

8.-Active electrodes are used in the cap. The reference goes on the earlobe. Gel is applied to each electrode.

9.-Applying gel involves moving hair to expose the scalp, filling gel to the electrode top without bridging between electrodes.

10.-The g.Recorder software is used to view the EEG. Amplifier and channels are selected.

11.-A previously recorded EEG training file with Andras is loaded into EEGLAB for demonstration.

12.-Channel locations are imported. Different plots, filtering and epoching of the data are shown.

13.-Noisy epochs can be rejected. Baseline adjustment is performed. ERP images and average waveforms can be plotted.

14.-The N100 auditory evoked potential is visible on the Cz electrode after averaging.

15.-Slides on evoked potentials are presented. Various paradigm design software packages are discussed.

16.-Triggering solutions are reviewed, including parallel port, software, and LSL. G.TEC's g.USBamp and g.HIamp amplifiers are recommended.

17.-A 64-channel visual evoked potential example is shown, with real-time raw data and averaged waveforms visible during acquisition.

18.-The visual N170 peaks around 170ms on occipital and parietal channels. P100 and Cz peaks are also seen.

19.-Similar results were obtained with g.Nautilus dry electrodes, demonstrating their potential for visual evoked potentials under certain conditions.

20.-The lecture switches to demonstrating Simulink for real-time evoked potential processing, using customized blocks optimized for EEG.

21.-The g.HIamp amplifier is selected in the block settings. The vibrotactile paradigm is chosen.

22.-Nice alpha waves are visible when the subject closes their eyes, confirming a good EEG signal.

23.-The vibrotactile stimulator is placed, with left pulses as targets to be counted by the subject.

24.-Triggers are output on channel 9 for later offline averaging to find the P300.

25.-The Simulink model includes acquisition, paradigm, visualization, filtering, data saving, event counting, and averaging blocks.

26.-In response to a question, LSL is not recommended for precise ERP timing due to delay and jitter issues.

27.-Sampling frequency is chosen based on the expected ERP latency, with higher frequencies needed for shorter latency components.

28.-Stress can be assessed in g.BSanalyze by deriving heart rate variability from ECG and correlating it with EEG band powers.

29.-For precise ERP timing, the g.TRIGbox parallel port interface or E-Prime software are recommended over LSL.

30.-A video demonstrates applying gel to passive EEG electrodes, showing the ideal gel amount to cover the electrode without bridging.

Knowledge Vault built byDavid Vivancos 2024