EEG Session 2: Reflective State

This page contains the data and analysis of a brain wave recording session I did using a Muse EEG Headband.

Session Characteristics

  • 30/09/2023, 22:24
  • I had slept a long nap and was feeling very calm and relaxed.
  • I was lying down in bed with my eyes closed.
  • This session was immediately preceded by Session 1, which was similar in everything except it was done with open eyes.

All Sensors

  • Compared to Session 1, no large oscillations occurred regularly because the eyes were closed, so there was no blinking.
  • As expected in a relaxed state with closed eyes, theAlphabrain waves dominated.
  • Beyond that, we see a relationship between the other frequencies that is to be expected for such a relaxed state — an intermeshed band ofTheta,DeltaandBeta(withThetadominating), andGammaoccupying the lowest place in dominance. This is similar to what we observed in Session 1.

Individual Sensors

  • Looking into each individual sensor, the same frequency relationship can be found in the Back sensors (TP10 and TP9).
  • In the Front sensors (AF7, AF8), the frequencies are closer to each other, forming a tighter band.
    • In the Front-Left sensor (AF7),BetaandGamma show a stronger dominance, sometimes even briefly oscillating towards first and second-place dominance. In any case, this brain quadrant is where these two frequencies are known to more easily achieve higher dominance levels.
    • Interestingly, in both Front sensors, there are some frequent oscillations, visually identifiable by looking atDelta,which are very similar to the ones observed in Session 1, and characterized there as being blinking artifacts. However, since the present session was done with eyes closed, that can’t be applied here, and raises some doubt on whether they really were blinking artifacts in the previous session. Further sessions will be conducted in the future to exclusively study blinking artifacts.

Absolute Average Values (All Sensors)

  • Alphaaverage: 76 dB
  • Thetaaverage: 55 dB
  • Deltaaverage: 53 dB
  • Betaaverage: 47 dB
  • Gammaaverage: 32 dB

Percentual Average Values (All Sensors)

  • Alphaaverage: 46%
  • Thetaaverage: 18%
  • Deltaaverage: 17%
  • Betaaverage: 12%
  • Gammaaverage: 7%

  • When theAlpharange becomes so dominant (as a consequence of closing the eyes), its percentual dominance increases.
    • The percentage of all frequencies must always add up to 100%, so ifAlphaincreases, some other frequencies must decrease.
    • Compared with Session 1 we can observe this decrease occurring inDelta(34% → 17%) andTheta(21% → 18%).
    • Betaremains the same.
    • However, in terms of Gamma,there is a large increase in dominance (3% → 7%).
      • This increase is interesting but its significance and meaning remain unknown at this point.

Brainwave Lateralization

  • Unfortunately, the Center of Gravity graphs are not available due to the short session duration (my bad!). However, using the visual data from the image above, we can say that:
  • Deltaseems to be Symmetrical with a pull to the Back. This last detail makes this behavior different from Session 1.
  • Theta’sandAlpha’scenters of gravity have a slight tendency to the Right with a pull to the Back. This seems to be identical with Session 1, but in a more pronounced manner.
  • Beta’scenter of gravity seems to be Symmetrical a slight tendency to the Left and a pull to the Back. This seems to be identical with Session 1.
  • Gamma’scenter of gravity seems to be Left dominant, with a pull to the Back. This seems to be identical with Session 1, but the pull to the back is not as strong.
  • Overall, closing the eyes doesn’t seem to change the brainwave localization behavior much, but I will repeat the experience in the future to have access to the Center of Gravity graphs of both sessions.

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