Choice of reference in analysis of CAEPS to auditory and audiovisual stimuli

Pia Gyldenkaerne, Mridula Sharma, Suzanne C. Purdy, John Seymour, Harvey Dillon

Research output: Contribution to journalMeeting abstract


A general principle of EEG measurements is that each recorded channel represents the difference in activity between two electrodes on the head. Use of different reference schemes between studies may contribute, among other factors, to inconsistencies of findings (Hagemann, 1998). This study investigates the effect of choice of reference on the CAEPs to auditory and audiovisual stimuli in normal hearing adults. The CAEPs were recorded to natural speech tokens presented as auditory, visual and audiovisual stimuli. The CAEPs were recorded with FCz as a reference and re-referenced offline to right mastoid, left mastoid, mean mastoids and an average reference respectively. The amplitude of the average reference waveforms were significantly smaller compared to the other references. Three of the four references (right, left and mean mastoids) showed a temporal facilitation with shorter latencies for N1 in the audiovisual condition. No latency differences were found for the average reference. All references showed a modality effect with audiovisual stimuli resulting in significantly enhanced N1/P2 amplitudes compared to auditory. The results suggest that the choice of reference has a significant effect on the temporal analysis of CAEPs and emphasise the importance of indication and justification of any choice of reference.
Original languageEnglish
Pages (from-to)232
Number of pages1
JournalClinical EEG and neuroscience
Issue number3
Publication statusPublished - 2012
EventAustralasian Cognitive Neurosciences Conference (21st : 2011) - Sydney
Duration: 9 Dec 201112 Dec 2011


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