combined EEG Instrumentation & Artifacts Exam multiple choice

Which montage primarily localizes activity by phase reversals?

Bipolar

Common mode rejection (CMR) refers to the amplifier’s ability to:

Reject identical signals at both inputs

A differential amplifier measures:

The difference between input 1 and input 2

If a negative signal enters Input 1( input 1 more negative than input 2), the deflection typically moves:

Upward

Sensitivity is measured in:

μV/mm

Increasing the sensitivity setting (μV/mm) makes waveforms appear:

Attenuated

In a referential montage, localization is based mainly on:

Amplitude differences

Muscle (EMG) artifact is most often prominent in

Temporal/frontal regions

The 60 Hz (notch) filter primarily targets

Electrical interference

A clear phase reversal in a bipolar chain usually indicates:

A focal localization point

The time constant is part of which filter system?

Low frequency filter

Impedance measure

Resistance at an electrode site

Channel polarity is determined by:

Input 1-input 2

A low frequency filter (LFF) attenuates:

Slow activity

A high frequency (HFF) attenuates:

Fast activity

Filters affect the amplitude of EEG waves, not the:

Frequency

When ‘end of chain’ localization is suspected in a bipolar montage, the best first step is to:

Change montage to Hat

The human eye behaves electrically as a:

Dipole

The LFF is commonly used to reduce:

Slow baseline drift/sweat components

The HFF is commonly used to reduce:

Fast activity/EMG components

In a longitudinal (double banana) montage, a focal spike is most confidently localized at the site of the:

Phase reversal

In a referential montage, a focal spike is most confidently localized at the electrode with:

Highest amplitude to reference

Which montage best highlights interhemispheric asymmetries across the midline (F7-F8 vs T3-74 etc)?

Transverse (coronal) bipolar

Which filter is best to reduce sweat artifact without eliminating alpha?

Increase LFF (raise from 0.1 to 1 Hz)

Raising sensitivity from 7 uv/mm to 10 uv/mm will make a 70 uv spike appear:

Attenuated

Which rhythm is most reactive to eye opening in awake adults?

Alpha

When blocking (clipping) occurs due to very high amplitudes, the quickest adjustment prevent further blocking is to:

Increase sensitivity

Which artifact produces steep, irregular, high frequency activity (>20Hz) predominantly in frontal-temporal channels?

EMG (muscle)

Lowering the high-frequency filter form 70 Hz to 35 Hz will likely:

Reduce EMG contamination

The notch filter should be used:

Only when necessary due to potential waveform distortion

In average reference montage, a unilateral focal spike may appear smaller if:

Many electrodes are involved by the same field