Phase-locked and non-phase-locked response components to auditory stimuli.
Anna Samsel
Research Seminar in framework of doctoral education
When?
Monday, 22 January 2018, 16:00-17:00
Where?
HP 1 (Seminar room 04.226)
O&N 2 - KU Leuven
Herestraat 49
B-3000 Leuven
Abstract
Neural processing of the speech envelope modulations is important for speech understanding (Peelle, 2012). Sensitivity to amplitude modulation of the sound can be investigated with envelope following responses (EFRs). The temporal modulation transfer function (TMTF) is the neural response amplitude as a function of the frequency of the fluctuation, and measuring ASSRs for many discrete modulation frequencies allows to trace maturation of the auditory pathway at different levels. Gransier et al. (2016) recently obtained TMTF in cochlear implant users by measuring ASSRs. This study revealed variability in ASSR amplitude for frequencies in 1- 20 Hz range and a decrease in responses for high modulation rates (80-100 Hz). We want to investigate these findings in more detail, in particular the decrease of amplitude in the high frequency range.
Activity due to the presence of the stimulus can be of two types: evoked or induced. The evoked component of the response corresponds to the activity that is phase-locked (synchronized) to the stimulus. The induced activity is time-locked but not-phase-locked to the stimulus. We hypothesize that the decrease in amplitude for 80-100 Hz presented by Gransier et al. is due to a decrease of phase-locking in the response. This could entail the presence of induced responses.
During this research seminar I will present results of our attempts to disentangle phase-locked and non-phase-locked components of response to auditory stimulus.
Please reply to this email if you are planning to attend the presentation.
