Cortical Event-Realated Potentials to Auditory Stimuli 초고주파 및 항공전자통신 연구실 석사 2 차 : 임의선 （林宜宣） Lin Yixuan

Microwave & Avionics LAB. 2/14 Contents Case Studies Clinical Application Of Auditory Cortical ERPS Description Of Responses General Technical Issues For ERPS Classification Of Auditory Event-Related Potential

Microwave & Avionics LAB. 3/14 Auditory Event-Related Potential  Event-related potentials (ERPs) are brain responses time-locked to some “event”. This event may be a sensory stimulus, a mental event, or the omission of a stimulus.  Auditory evoked potentials (AEPs) are brain responses “evoked” by the presentation of auditory stimuli.  Auditory evoked potentials (AEPs) are a subclass of ERPs,the "event" is a sound.

Microwave & Avionics LAB. 4/14 Classification of Auditory Event-Related Potentials Two major categories ERPs:  sensory (auditory) evoked potentials (sensory EPs)  Auditory sensory EPs reflect activation of the auditory pathways, from the cochlea to the cortex.(at late as 300ms).Often called “exogenous”.  processing-contingent potentials(PCPs)  PCPs represent processing are associated with further processing of sensory stimuli, beyond that driven by the physical properties of the stimulus. PCPs present processing beyond the obligatory sensory processing stages. Often called ”endogenous".

Microwave & Avionics LAB. 5/14 General Technical Issues For ERPS Stimulation Techniques Artifact Issues Multiple-Chanel Recordings Cortical ERP Measures

Microwave & Avionics LAB. 6/14 1 Stimulation Techniques  “oddball” technique, It may be two different stimuli :a stimulus and an omitted stimulus,or the same stimulus but presented at a different intensity,ear,etc. IT requires two different event which are standard and deviant; “standard” is presented for most of trials “ deviant” is presented for the remainder of the trials.

Microwave & Avionics LAB. 7/14 2 Artifact Issues Electrical potentials generated by eye movements and blinks are a major problem when recording cortical ERPs Approaches methods: All require one or two electroencephalographic(EEG) analysis channels that preferably record the electro-oculogram(EOG).At a minimum,the EOG is monitored using electrodes above and below the eyes.A second EOG channel for horizontal eye movements also may be monitored if electrodes are placed on the outer canthi.  Electroencephalography (EEG) is the recording of electrical activity along the scalp produced by the firing of neurons within the brain. refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes placed on the scalp.  Electrooculography (EOG) is a technique for measuring the resting potential of the retina.

Microwave & Avionics LAB. 8/14 3 Multiple-Channel Recordings  An individual reviewing the nonaudiology cortical ERP literature will quickly see that most studies over the past 10years obtain recordings for at least 8to 16 EOG/EEG channels and that recent papers now obtain recording for 32,64,or 128 channels. The purpose determines the minimum number of channels require. The purpose determines the minimum number of channels require The Waveguard EEG electrode caps are available with configurations of 21, 24, 32, 64, 128 and even 256 electrodes!

Microwave & Avionics LAB. 9/14 4 Cortical ERP Measures  Amplitude measures and Latency measures.  Amplitude measures are almost always obtained for cortical ERPs. Amplitude measures and Latency measures may be report for one electrode site,several electrode sites, several electrode sites, or a large number of sites, depending upon the purpose of study.  Additional wave form manipulations are often performed prior to obtaining latency and amplitude measures.  One must realize that the resulting difference wave may reflect latency/amplitude differences between the sensory responses to the different stimuli,or stimulus-spcific refractory characteristics,rather than a task-dependent or change-detection process.

Microwave & Avionics LAB. 10/14 Description Of Responses Slow Cortical Response(P1-N1-P2) MMN Late attention-related waves(N2b-P3b) Late language-related waves(N400;P600)

Microwave & Avionics LAB. 11/14 Slow Cortical Response(P1-N1-P2 ）  The "Slow" cortical auditory ERPs, which include the P1-N1-P2 sequence ( ms poststimulus; originating in auditory cortex). N1 is the large negative wave that occurs about ms after the stimulus. It originates primarily in the auditory cortex bilaterally. In the figure to the left, it is the large negative wave seen both in the response to the "standard" (black line) and the "deviant" (or oddball; red line) stimuli.

Microwave & Avionics LAB. 12/14  Compare with several auditory ERPs/AEPs originates in the 8th cranial nerve and brainstem auditory structures Includes waves Na and Pa The MMN is a response reflecting detection by the brain of a change in the stimulus. In the figure to the left, the MMN is the increased negativity seen in the response to the deviant or change stimuli (red line), at about the time of N1 and a little later.

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