BCIA Instrumentation & Technology

Question 1

What is the primary purpose of a differential amplifier in biofeedback instrumentation?

Accepted Answer

To reject common-mode noise and amplify the difference between two inputs

Answer

A differential amplifier rejects common-mode electrical noise while amplifying the difference between the active and reference electrodes.

Question 2

Which electrode placement standard is most commonly used in EEG-based neurofeedback?

Accepted Answer

International 10-20 System

Answer

The International 10-20 System is the universally accepted standard for electrode placement in EEG and neurofeedback practice.

Question 3

What does impedance checking before a biofeedback session primarily ensure?

Accepted Answer

Good electrical contact between electrodes and skin

Answer

Low impedance between electrodes and skin ensures minimal signal distortion and high-quality biosignal acquisition.

Question 4

EMG biofeedback electrodes are typically placed how far apart on a muscle?

Accepted Answer

2–4 cm

Answer

A spacing of 2–4 cm between surface EMG electrodes captures localized muscle activity with minimal cross-talk from adjacent muscles.

Question 5

What artifact commonly contaminates surface EMG recordings?

Accepted Answer

Cardiac artifact (ECG)

Answer

The electrical signal from the heart (ECG) can superimpose on surface EMG, particularly when recording from trunk muscles.

BCIA - Biofeedback Certification International Alliance Practice Test