Electrophysiology Review 2024

What are Auditory Evoked Potentials?

• Responses within the auditory system stimulated or evoked by sounds

• Neuro-electric signals that travel down the axon

• Endogenous EEG signals that allow you to infer the health of the cochlea

• Behavioral responses generated by pure tones

What are neurons?

• Electrically excitable cells that make up the nervous system

• Signals that travel down the axon

• Potentials evoked by an auditory stimulus

• Receptors that bind to neurotransmitters

Where do clicks best stimulate the cochlea?

• The first turn of the cochlea around 2-4 kHz

• The base of the cochlea around 0.5 kHz

• The apex of the cochlea around 5-6 kHz

• The middle of the cochlea around 4-5 kHz

How is a dipole generated?

• Transmembrane ionic current flow creates negative sink & positive source charges in the extracellular space separated by a small distance

• By neurotransmitters binding to receptors

• A cell creates a negative source and that negativity propagates through the skin and muscles

• A cell becomes positive and then travels through skin

Why are ABR recordings completed twice at the same protocol settings?

• To ensure the waves are replicable

• To increase the wave amplitudes

• To decrease the wave latencies

• To enhance the wave frequency

Which is NOT a factor that influences volume conduction of a neural signal?

• Dipole negativity

• Distance of recording electrode from dipole

• Geometric orientation of neuronal population

• Temporal synchrony of firing neurons

How does intensity affect AEP latency and amplitude?

• Latency decreases and amplitude increases with greater intensities

• Latency increases and amplitude decreases with greater intensities

• Latency and amplitude both increase with greater intensities

• Latency and amplitude both decrease with greater intensities

What causes an action potential?

• Membrane potential depolarizes and crosses threshold potential due to excitatory input

• Binding of neurotransmitters to receptors leading to more negative intracellular environment

• Evoked potentials by an auditory stimulus

• Resting potential of -70 mV

What is an ASSR?

• A steady-state AEP evoked by periodically varying, continuous stimuli

• A rapid response to sudden loud noises

• A slow response to low-frequency sounds

• A temporary change in hearing sensitivity

How does frequency affect the duration of tone bursts? Assume identical number of cycles

• Higher frequency = shorter duration

• Higher frequency = longer duration

• Lower frequency = shorter duration

• Duration does not change if the number of cycles is identical across frequencies