EEG

Question 1

Describe how EEG is used to study cortical responses to sensory, perceptual, and motor events

Answer 1

• Measuring electrical current/potentials created on teh scalp surface (with electrodes)
• Each different section of scalp corresponds to location on body

Question 2

Define and describe what event-related potentials are

Answer 2

• Changes in EEG that are time-locked to a sensory, motor, or cognitive process
• Used to determine time-cours (and location) of processes in the brain
• Provides electrophysiological window into brain function

Question 3

How are event related potentials extracted from EEG?

Answer 3

• Averaging multiple EEG waveform timelocked to event
• Removes unrelated activity form the waveform

Question 4

Describe the contingent negative variation, the CNV’s components, how its measured, and relation to volitional motor preparation

Answer 4

• Slow negative wave during foreperiod between a warning and an imperative signal of a quick response
• Components: Early orienting-related wave; late expectancy wave; motor preparation relative wave
• Largest amplitude over central area

Question 5

Describe the Readiness Potential

Answer 5

• Slow shift in cortical potential preceding a self initiated voluntary movement
• Starts 1000-2000ms prior to movement
• Bilateral, slowly increasing negative wave
• Appears over precentral, central, and parietal areas
• Associated with volitional preparation of movement

Question 6

How is the Readiness Potential Measured?

Answer 6

• EEG

Question 7

What are the Components of a Readiness Potential?

Answer 7

• Early RP (1-2s) beefore EnsMG onset
• Late RP (negative slope- NS) 300-500ms prior to EMG
• Motor Potential (MP) 50-100ms before emg onset

Question 8

Describe the Lateralized Readiness Potential

Answer 8

• Derived from asymmetric lateralization of readiness potential immediately preceding response

Question 9

Where is the LRP onset?

Answer 9

• End of response selection
• start of response programming

Question 10

How do you identify the LRP?

Answer 10

• Identify RP for both ipsilateral and contralateral sides
• Average them both

Question 11

Describe and explain how reaction time is fractionated with the use of EMG

Answer 11

• Premotor time and motor time

Question 12

Describe and Explain how reaction time is fractionated with the use of LRP

Answer 12

• Premotoric (stimulus onset and LRP onset) and motoric
• Stimulus Identification, response selection, and then response programming

Question 13

Define and distinguish between the stimulus locked LRP and response-locked LRP

Answer 13

When stimulus locked
- comparing time relative to stimulus onset
- how long the pre-motoric processing takes
When response locked
- comparing time relative to response onset
- how long it took for response programming

Question 14

Describe and explain the use of LRP in the study of motor preparation, and its division of response selection from response programming process?