[BME] Biopotentials (ECG, EMG, EEG)

Biopotentials

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Broadband Neural Siganl
= Spikes(High frequency) + Local field potential(LFP, Low frequency)

Electrogram

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1. Electrocardiogram (ECG)

Lead I, II, III

Standard line lead: bipolar measurement
두 개의 전극을 가지고 +/- input terminal에 연결
나머지 전극은 ground input에 연결

aVR, aVL, aVF

Augmented lead: unipolar measurement
한 lead를 (+), 나머지 두 개의 전극을 묶어서 (-) input terminal에 연결

2. Electromyogram

Intramuscular EMG

  • inserting a needle through the skin
    Surface EMG
  • placing the lectrodes on the skin

3. EEG

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EEG Source

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Excitatory input signal
Low frequency, Long period
Conduction signal(Action potential)
High frequency, Short period
All or None

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  1. dura mater, skin, hair 등 여러 장벽이 존재하기 때문에 약한 신호는 측정할 수 없다.
  2. 측정하는 것은 그나마 강한 low frequency의 post-synaptic potential이다.

Scalp EEG measures summated activty of post-synaptic potential(sum of synchronous activty). It is impossible to determine the activity wihtin a single dendtrite or neruon from scalp EEG.

4. Biopotentials related with Vision

EOG Eye battery measurement(눈이 어디 방향으로 향해있는가)
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  • single dipole
  • well established (0.4~1.0mV)
  • moving dipole source

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ERG electrical response of retina to optical stimulation

  • a mass electrial response of retina to photonic stimulation

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Visually Evoked Potential(VEP), EEP(retinal prosthesis)

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