Electrical Systems & Wiring Flashcards

During ABR electrode placement, the non-inverting (positive) electrode is conventionally placed at:

Answer: The vertex (Cz) or high forehead (Fz)

The non-inverting electrode at the vertex or high forehead captures the far-field brainstem response with maximal amplitude due to the electrode's proximity to the response generator orientation.

Electrode impedance imbalance between the inverting and non-inverting electrodes is problematic because it:

Answer: Reduces CMRR, allowing more environmental noise into the recording

Unequal electrode impedances convert common-mode interference into differential-mode signal, degrading the amplifier's ability to reject environmental noise.

For electrocochleography (ECochG), a tympanic membrane or transtympanic electrode is preferred over a surface electrode primarily because:

Answer: Proximity to the cochlea increases the amplitude of CM, SP, and AN components

Placing the electrode on or through the tympanic membrane dramatically increases signal amplitude by reducing the distance from the generator (cochlea) to the recording electrode.

In ASSR recording, the multiple auditory steady-state response (MSSR) technique uses different modulation frequencies for each ear/frequency because:

Answer: Different modulation rates prevent interference between simultaneously presented signals

Using distinct carrier-specific modulation rates allows simultaneous multi-frequency stimulation while mathematically separating each frequency's response in the spectral domain.

The primary reason for using a notch filter at 60 Hz during evoked potential recording is to:

Answer: Attenuate AC line-frequency electrical interference without affecting neural components

A 60 Hz notch filter selectively attenuates power-line interference while leaving neural response frequencies relatively intact, improving signal-to-noise ratio.

Stimulus artifact in an ABR recording is most effectively minimized by:

Answer: Using insert earphones to create a physical and electrical delay between stimulus delivery and neural response

Insert earphones introduce a ~1 ms acoustic tube delay, temporally separating the electrical stimulus artifact from the early neural responses such as Wave I.

In auditory evoked potential systems, the analog-to-digital converter (ADC) sampling rate must be at least twice the highest frequency of interest according to:

Answer: The Nyquist-Shannon sampling theorem

The Nyquist-Shannon theorem states that to accurately represent a signal, the sampling rate must be at least twice the highest frequency component to avoid aliasing.