Pupillary Response in an Auditory Rhythm Omissions Task in Parkinson´s Disease: A Pilot Study

Abstract

When presented with short, rhythmical, musical excerpts, containing omitted beats which vary in saliency in terms of rhythmical patterns (contextual omission), and position (salience omissions), fMRI studies have shown a small effect depending on position of omission. Furthermore, when presented with auditory stimuli, a pupillary dilation response (PDR) is evoked, resulting in a pupillary peak dilation (PPD) sometime after stimulus onset. By utilizing and adapting an auditory beat-omission fMRI paradigm, to allow measurement of PDR and PPD, we used pupillometry data to investigate the effect of contextual omission (Simple vs Complex rhythm) and salience omission (O1 vs O2). We report data from a total of 25 participants, based on 45 datasets. The data were analyzed using four separate direct t-tests. We found that the omission has an effect on PPD, in that the most metrical salient omission (O1) results in a higher activation level compared to a less salient omission (O2), i.e., PPD was significantly higher in O1 simple rhythm omissions, and in O1 complex rhythm omissions, at an uncorrected threshold level.