Sensory thresholds obtained from MEG data: cortical psychometric functions

Caroline Witton, Tulpesh Patel, Paul Furlong, Sian Worthen, G. Bruce Henning, Joel Talcott

Research output: Contribution to journalArticlepeer-review


Sensory sensitivity is typically measured using behavioural techniques (psychophysics), which rely on observers responding to very large numbers of stimulus presentations. Psychophysics can be problematic when working with special populations, such as children or clinical patients, because they may lack the compliance or cognitive skills to perform the behavioural tasks. We used an auditory gap-detection paradigm to develop an accurate measure of sensory threshold derived from passively-recorded MEG data.
Auditory evoked responses were elicited by silent gaps of varying durations in an on-going noise stimulus. Source modelling was used to spatially filter the MEG data and sigmoidal ‘cortical psychometric functions’ relating response amplitude to gap duration were obtained for each individual participant. Fitting the functions with a curve and estimating the gap duration at which the evoked response exceeded one standard deviation of the prestimulus brain activity provided an excellent prediction of psychophysical threshold.
Thus we have demonstrated that accurate sensory thresholds can be reliably extracted from MEG data recorded while participants listen passively to a stimulus. Because we required no behavioural task, the method is suitable for studies of populations where variations in cognitive skills or vigilance make traditional psychophysics unsuitable.
Original languageEnglish
Pages (from-to)1249-1256
Number of pages8
Issue number3
Early online date11 Aug 2012
Publication statusPublished - 15 Nov 2012


  • auditory
  • gap-detection
  • MEG
  • psychophysics
  • threshold


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