Describe how EEG is used to study cortical responses to sensory, perceptual, and motor events
- Measuring electrical current/potentials created on teh scalp surface (with electrodes)
- Each different section of scalp corresponds to location on body
Define and describe what event-related potentials are
- 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
How are event related potentials extracted from EEG?
- Averaging multiple EEG waveform timelocked to event
- Removes unrelated activity form the waveform
Describe the contingent negative variation, the CNV’s components, how its measured, and relation to volitional motor preparation
- 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
Describe the Readiness Potential
- 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
How is the Readiness Potential Measured?
- EEG
What are the Components of a Readiness Potential?
- 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
Describe the Lateralized Readiness Potential
- Derived from asymmetric lateralization of readiness potential immediately preceding response
Where is the LRP onset?
- End of response selection
- start of response programming
How do you identify the LRP?
- Identify RP for both ipsilateral and contralateral sides
- Average them both
Describe and explain how reaction time is fractionated with the use of EMG
- Premotor time and motor time
Describe and Explain how reaction time is fractionated with the use of LRP
- Premotoric (stimulus onset and LRP onset) and motoric
- Stimulus Identification, response selection, and then response programming
Define and distinguish between the stimulus locked LRP and response-locked LRP
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
Describe and explain the use of LRP in the study of motor preparation, and its division of response selection from response programming process?
