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P300/MMN recording

What is a MMN/ P300/?

The mismatch negativity (MMN) response is a negative wave elicited in an ‘oddball’ paradigm where by a deviant stimuli is presented amongst a stream of repeated, or standard, stimuli. The response can be observed by subtracting the responses to the standard stimuli from those of the deviant, and it occurs in the latency region of around 100-300ms. See Fig1, showing an MMN from a 2 kHz deviant tone burst presented amongst a stream of 1 kHz standard tone bursts, measured between vertex and linked- mastoid positions.

Figure 1 MMN response

The P300 response is a positive wave that is also usually elicited in an oddball paradigm. Unlike the MMN, which can be measured without any task requirements, the P300 only occurs when the listener is actively attending to the stimuli. See Fig 2, showing a P300 from a 2 kHz deviant tone burst presented amongst a stream of 1 kHz standard tone bursts, measured between vertex and linked- mastoid positions.

Figure 2 P300 response

Why MMN/P300/?
The MMN and P300 can be used to evaluate higher level auditory function. The MMN test is particularly related to the brain’s ability to discriminate between speech sounds, and its independence of attention may make is suitable for use in evaluating auditory function in various populations in clinical neuroscience and in infants and newborns (Garrido et al., 2009).

How to test
Patient
Preparation is very important. Patient arousal and attention state greatly affects the amplitudes of the MMN response, so it is very important that the patient understands the test procedure. The MMN can also be elicited when the subject pays attention to stimuli, but it is difficult to measure in this condition because of the overlapping N2 component. As a result it is recommended to record the MMN while the subject ignores the stimuli. This can be done by letting the subject read or watch a silent captioned video during recording.

The MMN amplitudes decrease with various stages of sleep. It is not advised to perform MMN under sedation.

Electrode Placement:
It is possible to obtain P300/MMN with a standard 2-channel electrode montage, with an active vertex electrode referenced to either right or left mastoid. However, stronger responses can be obtained by linking the right and left mastoids, recording both from the ipsilateral and contralateral side in order to avoid a bias in hemispheric laterality.

Setting up the Eclipse
The Eclipse comes with a pre-programmed protocol for P300/MMN testing (license), ready for immediate use. Protocols can be created or modified easily to fit your clinic needs. Consult your Eclipse Additional Information to learn how to create or modify a protocol.

Protocol settings

  • P300/MMN should be measured using toneburst from 250 Hz-4 kHz and custom wave files at an intensity of a moderate levels.
  • Custom wavefiles inclusing Da, Ba and Ga are placed on the EPx5 CD-ROM. Please refer to the chapter Importing wavefiles for stimuli in Instruction for Use for guidelines on importing and calibrating custom wavefiles.

Summary of parameters for P300 and MMN

    P300 Response (deviant curve) MMN (subtracted curve frequent - deviant)
Subject State

Awake and quit adults, children and infants

Awake and quit adults, children and infants

Eyes Eyes open Eyes open
Condition Attend

Ignore conditions

Stimuli Types of stimuli

Tone burst, speech vowels or consonant vowel combinations

Tone burst, speech vowels or consonant vowel combinations

Inter-nset interval

0.1-1 sec

0.1-1 sec
Stimulus duration 

50-300ms

Be careful of overlapping response if analysis time is short

50-300ms

Be careful of overlapping response if analysis time is short

Presentation

Oddball paradigm
Deviant probability 0.05-0.20 Number of deviants at least 200

Oddball paradigm
Deviant probability 0.05-0.20 Number of deviants at least 200

Intensity

60-80dB peSPL

60-80dB peSPL

Recordings Reference electrode

Tip of nose of averaged reference (jumped electrodes)

Tip of nose of averaged reference (jumped electrodes)

Filtering

1-30Hz

1-30Hz
Analysis time

Pre stimuli -100ms
Post stimuli 700ms or more

Pre stimuli -100ms
Post stimuli 700ms or more
Sweep

50-300 (A total sweep of 2000, with 15% deviant stimuli gives 300 deviant sweeps.

50-300 (A total sweep of 2000, with 15% deviant stimuli gives 300 deviant sweeps.
Replications

At least 2, resulting in at least 200 deviants

At least 2, resulting in at least 200 deviants
Measurements 

Adult

Children

Infants

Measures

P1, N1, P2 & P3
P1, N200-250
Reliable components
Baseline to peak amplitude, peak latency

Use latency window established using grand mean data

N1, P2 & MMN

Any age, use difference waveform (response to deviant)

Baseline to peak amplitude, peak latency

Consider mean MMN amplitude in response window

Use latency window established using grand mean data

Response presence  Determined by

Replicable components

Response 2-3 times larger than amplitude in pre-stimulus interval

Replicable components

Response 2-3 times larger than amplitude in pre-stimulus interval

 


References
Garrido, M. I, Kilner, J.M, Stephan., K.E., and Friston, K.J. (2009) The mismatch negativity: A review of underlying mechanisms. Clinical Neurophysiology 120 453–463.

Hall, J.W. (2007). New Handbook of Auditory Evoked Responses. Pearson
Picton, T. (1992) The P300 wave of the human event-related potential. Journal of Clinical Neurophysiology 9 (4) 456-479.

July 2017
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